Starkey Research & Clinical Blog

Hearing Aid Use is Becoming more Accepted

Rauterkus, E. & Palmer, C. (2014). The hearing aid effect in 2013. Journal of the American Academy of Audiology 25, 893-903.

This editorial discusses the clinical implications of an independent research study and does not represent the opinions of the original authors.

Years ago, one of my patients quoted an aphorism, “Your hearing loss is more noticeable than your hearing aid”. At the time, it wasn’t always applicable. Hearing aids were larger and more visible in the ear and whistling feedback was harder to control, often resulting in embarrassment for the wearer. Today’s hearing aids are smaller, discreet, and comfortable, with effective feedback management. Still, there remains concern among many current and potential hearing aid users about a negative stigma associated with hearing aid use. Despite numerous potential benefits like improved communication ability and decreased stress, listening effort and fatigue, hearing impaired individuals quite frequently postpone or avoid amplification because they believe that wearing hearing aids will cause others to label them as old or less capable.

These negative associations have collectively been described as the hearing aid effect. Blood, Blood and Danhauer (1977) coined this term during a study in which 25 college students were shown photographs of 12 teenage males with and without hearing aids. The participants were asked to judge the boys in the photographs in terms of intelligence, achievement, personality, and appearance. On all attributes, the participants rated the boys in the photographs lower when they were wearing hearing aids versus when they were not.  Since their initial study, other reports showed a similar hearing aid effect (Blood, et al., 1978; Danhauer et al., 1980; Brimacombe & Danhauer, 1983).  Studies in which children rated other children showed strong and consistently negative judgments of individuals with hearing aids, on attributes such as intelligence and attractiveness (Dengerink & Porter, 1984; Silverman & Klees, 1989).  In contrast, some studies in which adults rated other adults did not find a hearing aid effect (Iler et al., 1982; Johnson & Danhauer, 1982; Mulac et al., 1983).

In general, a review of several reports from 1977 through 1985 indicates that hearing aid stigma at that time may have been changing slowly for the better.  A much more recent study (Clucas, et al., 2012) essentially reported the opposite of the typical hearing aid effect, in which 181 medical students rated photographs of a young male wearing a hearing aid as more worthy of respect than the photographs of the same young male without the hearing aid.

Through the years, hearing aids have become smaller and more discreet. Feedback reduction, automatic features and improved performance in noise have allowed hearing aid users to function better in everyday situations, calling less attention to their hearing loss. Ear level devices like earbuds for MP3 players and Bluetooth headsets have become widely used and visible. The Americans with Disabilities Act (ADA) has promoted equal participation of disabled individuals, including those with hearing loss. Public figures have openly discussed their hearing loss and hearing aid use, including Presidents Ronald Reagan and Bill Clinton and musicians like Pete Townsend and Neil Young. All of these factors have likely had a positive influence on public perception of hearing loss and hearing aids and may have reduced the negative stigma so prevalent in earlier reports.

The hearing aid effect, however, has not been re-examined in the same paradigm as the original report, so it is unknown how today’s perceptions might compare to the defining work. Rauterkus and Palmer’s study asked young adults to view and evaluate photographs of young men with and without hearing aids, in an effort to replicate the methods of earlier studies and derive an understanding of the hearing aid effect today.

Twenty-four graduate students in an MBA program were recruited to evaluate photographs of 5 young men, from age 15-17 years. The young men were photographed in 5 different configurations:

1. Wearing a standard BTE hearing aid coupled to a standard earmold and tubing

2. Wearing an open-fit BTE hearing aid coupled to a slim tube and dome

3. Wearing a CIC hearing aid that was not visible in the photo

4. Wearing earbud headphones as would be used with an MP3 device

5. Wearing a Bluetooth ear-level telephone headset

In the pictures, the young man was seated, reading a book. All photographs were taken from the rear left side of the young man, so that the left side and back of his head was visible and ear level devices could clearly be seen. All of the men in the pictures wore the same clothing so that differences would not affect the judgments of the participants.

No participant viewed the same man in more than one device configuration. Each photograph was shown on a page above a list of 8 attributes: attractive, young, successful, hard-working, trustworthy, intelligent, friendly, and educated. Participants were asked to rate the man in the picture on each attribute on a scale of 1-7.  These 8 attributes were selected because they were the most common attributes to have been rated in previous studies of the hearing aid effect.

The results showed no significant difference in ratings among the five young men in the photographs. Therefore, the data for all of the photographs were combined for data analysis.  There was a significant difference in the judgment of age between the photographs of the CIC user and the earbud user, with the CIC user being judged as significantly older than the earbud user.  Because the CIC instruments were not visible in the photographs, this difference is likely to be related to an association between younger people wearing earbuds to listen to music, as opposed to a negative judgment on the use of CIC instruments.  There was a significant difference in trustworthiness between the BTE user and Bluetooth device user, with the Bluetooth headset user deemed significantly less trustworthy. The authors’ findings clearly indicate that the participants did not have adverse reactions to the photographs of hearing aid users and did not demonstrate the hearing aid effect found in earlier studies.

The work of Rauterkus and Palmer suggests the hearing aid effect has diminished or even reversed. A welcome message for hearing care professionals, but we must also understand self-perception of hearing aid use. One could speculate that the commonality of ear-level devices and improvements in hearing aid size, design, performance and connectivity, have improved others perception of hearing aid use, resulting in the documented decrease of the hearing aid effect. It’s possible that the same social and technological factors are taking a similar toll on the negative self-perception of hearing aid use. Time will reveal the reality of these trends but smart research design helps us take a peak into the not-too-distant future.

 

References

Blood, G., Blood, I. & Danhauer, J. (1977). The hearing aid effect. Hearing Instruments 28, 12.

Blood, G., Blood, I. & Danhauer, J. (1978). Listeners’ impressions of normal-hearing and hearing-impaired children. Journal of Communication Disorders 11(6), 513-518.

Clucas, C., Karira, J. & Claire, L. (2012). Respect for a young male with and without a hearing aid: a reversal of the “hearing aid effect” in medical and non-medical students? International Journal of Audiology 51(10), 739-745.

Danhauer, J., Blood, G., Blood, I. & Gomez, N. (1980). Professional and lay observers’ impressions of preschoolers wearing hearing aids. Journal of Speech and Hearing Disorders 45(3), 415-422.

Dengerink, J. & Porter, J. (1984). Children’s attitudes towards peers wearing hearing aids. Language, Speech and Hearing Services in Schools 15, 205-209.

Iler, K., Danhauer, J. & Mulac, A. (1982).  Peer perceptions of geriatrics wearing hearing aids. Journal of Speech and Hearing Disorders 47(4), 433-438.

Johnson, C. & Danhauer, J. (1982). Attitudes towards severely hearing impaired geriatrics with and without hearing aids. Australian Journal of Audiology 4, 41-45.

Mulac, A., Danhauer, J. & Johnson, C. (1983). Young adults’ and peers’ attitudes towards elderly hearing aid wearers. Australian Journal of Audiology 5(2), 57-62.

Rauterkus, E. & Palmer, C. (2014). The hearing aid effect in 2013. Journal of the American Academy of Audiology 25, 893-903.

Silverman, F. & Klees, J. (1989).  Adolescents’ attitudes toward peers who wear visible hearing aids. Journal of Communication Disorders 22(2), 147-150.

 

Tinnitus Treatment through Sound Therapy

Henry, J., Frederick, M., Sell, S., Griest, S. & Abrams, H. (2014). Validation of a novel combination hearing aid and tinnitus therapy device. Ear and Hearing, e-published ahead of print, September 2014.

This editorial discusses the clinical implications of an independent research study and does not represent the opinions of the original authors.

Background

Most tinnitus management programs include a combination of counseling and sound therapy (Jastreboff, 1990; Jastreboff & Hazell, 2004). The goals of sound therapy for tinnitus treatment include achieving immediate relief as well as facilitating long-term habituation to the tinnitus (Vernon, 1988; Jastreboff & Hazell, 1998). Many sound generators or tinnitus masking devices offer only basic amplification features because they were intended primarily for tinnitus treatment through sound therapy. Current combination devices with advanced digital signal processing can provide improved audibility and comfort in addition to offering noise stimuli (i.e., sound therapy) for tinnitus management. Some estimates report that up to 90% of patients with tinnitus may benefit from amplification (Johnson, 1998; Schechter et al., 2002) so combination hearing aid / sound therapy devices are a valuable tool for tinnitus treatment and hearing loss remediation.

Most scientific studies support the potential benefit of hearing aids for tinnitus management. In a recent literature review, Shekhawat et al. (2013) reported that 17 of 18 research studies included the use of hearing aids in tinnitus treatment, but they highlighted the absence of randomized control trials with hearing aids that include sound therapy options. Parazzini et al. (2010) found that open-fit hearing aids were as effective as sound generator-only devices for use in tinnitus therapy, but they did not investigate combination devices. A primary goal of therapy is to reduce tinnitus awareness, so combination devices could be particularly beneficial because they employ masking stimuli as well as amplified environmental sound that may effectively draw attention away from the tinnitus. Though this proposition has merit, it has not yet been supported by scientific evidence. To this end, Henry and his colleagues prepared a randomized, controlled trial to investigate the benefit of hearing aids versus combination devices for tinnitus management.

Methods and Findings

Thirty participants with mild-to-moderately severe, symmetrical, sensorineural hearing loss were recruited for this study. All had clinically significant tinnitus according to Section A of the Tinnitus and Hearing Survey (Henry et al., 2010a, 2012). At the first session, subjects completed audiometry, medical and tinnitus screening and responded to 3 questionnaires: the Tinnitus Functional Index (TFI; Meikle et al., 2012), the Hearing Handicap Inventory for the Elderly (HHIE; Ventry & Weinstein, 1982) and a general tinnitus survey.  The TFI evaluates the negative impact of tinnitus and measures changes in tinnitus impact after treatment. TFI scores range from 0 to 100, with higher scores indicating more severe problems. Scores of at least 25 are considered significant and a 13-point difference from one test administration to another is considered a significant change. The HHIE evaluates the social and emotional effects of hearing loss and higher scores indicate more social and emotional impact. In this study, the HHIE was administered face-to-face, so a change of 19 points from one session to another was considered significant.

At the second session, participants were fitted with receiver-in-canal (RIC) hearing instruments that included the Multiflex adjustable sound-generator. Most subjects used manufacturer’s silicone domes, but two required custom fitted acrylic earmolds. Hearing aids were programmed to NAL-NL2 targets, verified with real-ear measures and adjusted according for sound quality and comfort. Following hearing aid fitting, all participants received general tinnitus counseling derived from Progressive Tinnitus Management: Counseling Guide (Henry et al., 2010b). Following counseling, the experimental group had the tinnitus sound therapy in their hearing aids adjusted according to their individual preferences to obtain immediate relief from their tinnitus, while the control group was prescribed hearing aids without the tinnitus sound therapy.  The default settings for the modulated noise stimuli were based on the individual’s audiogram, but could be adjusted in 16 channels and subjects could select a slow, medium or fast modulation rate.

Approximately 3 to 4 months after the initial fitting appointment, participants returned to complete an exit interview. They were asked about their general impressions of hearing aids and experience of tinnitus relief and completed the TFI and HHIE inventories two more times; once to indicate their responses when they were using their hearing aids and again to indicate their responses when they were not using their hearing aids.

TFI and HHIE scores were obtained 3 times each: at the initial visit prior to hearing aid fitting and at the 3-month session, for responses referring to experiences with the hearing aids and without. The initial average TFI score for the overall subject group was 58.3. At the 3-month session, the average TFI scores were 22.2 (with hearing aids) and 44.8 (without hearing aids). Though the change in score for the with-hearing-aid condition was much larger, the reductions in score were significant for both conditions. For the control group, the initial score was 60.5 and at 3 months the average scores were 27.6 (with hearing aids) and 44.3 (without hearing aids). Again, both reductions were significant, though the effect size for the with-hearing-aids condition was much larger. For the experimental group, the initial average score was 56.1. At the 3-month session, the average scores were 16.8 (with hearing aids) and 45.3 (without hearing aids). The score reduction was significant for the with-hearing-aids condition but not for the without-hearing-aids condition. These outcomes indicate that both groups, regardless of whether the sound therapy was used or not, responded better to TFI questions with respect to when they were wearing the hearing aids versus when they were not.  There was no significant difference between the TFI score reductions for the control versus experimental groups, though the experimental group had a larger score reduction by about 6 points.

At the 3-month session, the average HHIE scores were 23.6 (with hearing aids) and 47.5 (without hearing aids). The score reduction was significant for the with-hearing-aid condition but was not for the without-hearing-aid condition. For the control group, the initial score was 55.3 and at 3 months the average scores were 26.9 (with hearing aids) and 47.5 (without hearing aids). For the experimental group, the initial average HHIE score was 49.3 and at the 3-month session the average scores were 20 (with hearing aids) and 47.5 (without hearing aids). Again, for both the control and experimental groups, the score reduction was significant for the with-hearing-aid condition but was not for the without-hearing-aid condition.  There was a significant main effect between initial scores and 3-month scores for the with-hearing-aid condition but not for the without-hearing-aid condition. There was also a significant difference between the two conditions at the 3-month session; the with-hearing-aid scores were significantly lower than without-hearing-aid scores.

Discussion

The findings of Henry and colleagues indicate that hearing aid use significantly reduces the negative effects of tinnitus, regardless of the presence or absence of sound therapy. Though there was not a significant difference between the control and experimental groups, the group using sound therapy had a larger reduction in TFI score than the group that used amplification alone. This difference approached but did not reach significance and the authors posit that perhaps with a larger subject group this difference would have been significant. HHIE results suggest that hearing aid benefit was not hampered by the use of sound therapy.

From a clinical perspective, several factors should be considered when fitting combination devices. The TFI is a good way to determine candidacy for combination devices, but a few key questions in the patient history can be helpful. We ask patients how they would rate their tinnitus and if it disrupts concentration, distracts or upsets them. It is also informative to ask if their tinnitus keeps them awake at night, though this concern is not directly addressed by the use of a combination device. Even a question about how motivated they are to seek treatment, such as the one employed in this study, can be indicative of candidacy.

After candidacy is established, there are still several factors to consider. Discussion of the individual’s tinnitus characteristics might help indicate which type of noise is most likely to be effective. Shaping the noise by frequency and intensity can help to achieve relief, while avoiding annoyance that may come with continued use. Clinicians should also discuss whether patients would like to use the noise constantly, in their main hearing aid program, or have it allocated to an alternate program for use as needed. We have found that most people prefer to have a “masking program” that they can use on occasion when their tinnitus is disruptive or annoying. For many people, this is in quiet conditions when they must concentrate on reading or quiet work. Follow-up consultations are critical to determine if the approach is working. Some individuals prefer to modify the characteristics of their sound therapy at later visits, either increasing or decreasing the intensity or shaping the frequency bands. The TFI is useful as a follow-up measure, but it should probably be administered after a few months of use, to make sure that programming adjustments are worked out before treatment efficacy is assessed.

References

Bock, K. & Abrams, H. (2013). An evaluation of the efficacy of a remotely driven auditory training program. Biennial NCRAR International Conference: Beyond the Audiology Clinic: Innovations and Possibilities of Connected Health. Portland, OR.

Coles, R. (2000). Medicolegal issues. In R.S. Tyler (Ed.). Tinnitus Handbook (pp. 399-417). San Diego: Singular Publishing Group.

Henry, J., Frederick, M., Sell, S., Griest, S. & Abrams, H. (2014). Validation of a novel combination hearing aid and tinnitus therapy device. Ear and Hearing, e-published ahead of print, September 2014.

Henry, J., Zaugg, T. & Myers, P. (2010a). Progressive Tinnitus Management: Clinical Handbook for Audiologists. San Diego, CA: Plural Publishing.

Henry, J., Zaugg, T. & Myers, P. (2010b).  Progressive Tinnitus Management: Counseling Guide. San Diego, CA: Plural Publishing.

Henry, J., Zaugg, T. & Myers, P. (2012). Pilot study to develop telehealth tinnitus management for persons with and without traumatic brain injury. Journal of Rehabilitation Research Developments 49, 1025-1042.

Hoffman, H. & Reed, G. (2004). Epidemiology of tinnitus. In J.B. Snow (Ed.). Tinnitus: Theory and Management (pp. 16-41). Lewiston, NY: BC Decker, Inc.

Humes, L., Wilson, D. & Barlow, N. (2002). Longitudinal changes in hearing aid satisfaction and usage in the elderly over a period of one or two years after hearing aid delivery. Ear and Hearing 23, 428-438.

Jastreboff, P. (1990). Phantom auditory perception (tinnitus): Mechanisms of generation and perception. Neuroscience Research 8, 221-254.

Jastreboff, P.  & Hazell, J. (1998). Treatment of tinnitus based on a neurophysiological model. In J.A. Vernon (Ed.). Tinnitus Treatment and Relief (pp. 201-217). Needham Heights: Allyn & Bacon.

Jastreboff, P. & Hazell, J. (2004). Tinnitus Retraining Therapy: Implementing the Neurophysiological Model. Cambridge University Press.

Johnson, R. (1998). The masking of tinnitus. In J.A. Vernon (Ed.). Tinnitus Treatment and Relief (pp. 164-186). Needham Heights: Allyn & Bacon.

Meikle, M. & Taylor-Walsh, E. (2012). Characteristics of tinnitus and related observations in over 1800 tinnitus patients. Proceedings of the Second International Tinnitus Seminar. New York 1983. Ashford, Kent, Invicta Press. Journal of Laryngology and Otology Suppl. 9, 17-21.

Mulrow, C., Tuley, M. & Aguilar, C. (1992). Sustained benefits of hearing aids. Journal of Speech and Hearing Research 35, 1402-1405.

Parazzini, M., Del Bo, L., Jastreboff, M., Tognola, G. & Ravazzani, P. (2010). Open ear hearing aids in tinnitus therapy: An efficacy comparison with sound generators. International Journal of Audiology 2011 Early Online, 1-6.

Schechter, M., Henry, J. & Zaugg, T. (2002). Selection of ear level devices for two different methods of tinnitus treatment. VIIth International Tinnitus Seminar Proceedings. R. Patuzzi. Perth, Physiology Department, University of Western Australia, p. 13.

Shekhawat, G., Searchfield, G. & Stinear, C. (2013). Role of hearing aids in tinnitus intervention: A scoping review. Journal of the American Academy of Audiology 24, 747-762.

Surr, R., Montgomery, A. & Mueller, H. (1985). Effect of amplification on tinnitus among new hearing aid users. Ear and Hearing 6, 71-75.

Ventry, I. & Weinstein, B. (1982). The hearing handicap inventory for the elderly: A new tool. Ear and Hearing 3, 128-134.

Vernon, J. (1988). Current use of masking for the relief of tinnitus. In M. Kitahara (Ed.). Tinnitus. Pathophysiology and Management (pp. 96-106). Tokyo: Igaku-Shoin.

Vernon, J. (1992).  Tinnitus: causes, evaluation and treatment. In G.M. English (Ed.). Otolaryngology (Revised Edition), pp. 1-25. Philadelphia: J.B. Lippincott.

Can hearing aid settings improve working memory?

Souza, P., & Sirow, L. (2014). Relating working memory to compression parameters in clinically-fit hearing aids. American Journal of Audiology, Just Accepted, released August 14.

This editorial discusses the clinical implications of an independent research study and does not represent the opinions of the original authors.

Working memory provides short-term processing and storage of information during complex cognitive tasks, combining information from numerous sources into a coherent whole (Baddeley, 1992). Incoming stimuli are compared and matched to long-term memory representations, prior to identification and further processing.

The term working memory describes our ability to store and process information during cognitively demanding tasks. In the context of hearing, working memory capacity affects ones ability to match speech inputs with stored representations of that speech. Several studies suggest that individuals with impaired working memory experience increased difficulty understanding speech in complex listening environments (Lunner, 2003). It is assumed that working memory tends to decline with advancing age (Salthouse, 1994). Therefore, it is important to understand how these variables affect speech perception and how they interact with each other, particularly for older hearing aid users.

Working memory may impact the optimal hearing aid characteristics for an individual and a number of studies have investigated the relationship between working memory and wide-dynamic range compression (Foo, et al., 2007; Gatehouse, et al., 2006; Lunner & Sundewall-Thoren, 2007; Ohlenforst, et al., 2014).  In these studies,  hearing aid compression speed was examined while keeping other amplification characteristics constant. Subjects with better working memory were generally found to perform better with fast-acting compression, whereas subjects with poorer working memory performed better with slow-acting compression.  The authors interpret these results as an indication that fast-acting compression alters the speech envelope in ways that make it more difficult to match incoming stimuli to stored lexical representations (Jenstad & Souza, 2007; Jenstad & Souza, 2005; Ronnberg et al., 2013; Ronnberg et al., 2008).

Laboratory experiments inherently must control the variables under study in order to glean meaningful interpretations. However, comparing fast and slow compression speed in isolation does not represent the typical conditions of a clinical hearing aid fitting, in which these characteristics are not independently adjustable. Furthermore, with changes in compression speed from one hearing aid model to another, many other variables are likely to differ as well, such as feedback management, noise reduction characteristics and the number of compression channels. These considerations make it difficult to extrapolate laboratory findings to everyday clinical experiences. The goal of Souza and Sirow’s study was to examine how compression speed and working memory relate to each other, using selection, fitting and verification techniques as they would typically be used in a clinical setting.

Twenty-seven participants with hearing loss were fitted with at least three different sets of receiver-in-canal hearing instruments, from several manufacturers. Because only one manufacturer offered an aid with adjustable compression speed, each subject completed a comparison of two compression settings with this single hearing aid, plus two or three additional models from other manufacturers that varied in their compression characteristics.  All aids were fitted with closed domes in the appropriate size for the individual. Real-ear verification and adjustments to prescribed levels were completed as they would in a typical clinical hearing aid fitting, to ensure audibility and comfort.  Aids were programmed with omnidirectional microphones and special hearing aid parameters such as feedback management and noise reduction were set according to manufacturer defaults.

Working memory is often assessed with a dual-paradigm task, in which the subject is required to process information while storing it for later recall. In this study, working memory was assessed with a reading span test, the same procedure used in previous studies of hearing aid compression and working memory. Subjects were presented with five-word sentences flashed on a computer screen and were asked to judge if the sentences made sense or not.  Sentences were presented one at a time in blocks of three, four or five. After each block, subjects were asked to recall either the first or last words of the sentences. The working memory score was taken as the percentage of correctly recalled words across all blocks.

Speech intelligibility was tested using the QuickSIN (Killion, et al., 2004) test, because of its ease of clinical administration and similarity to test materials and conditions in prior studies of compression (Lunner & Sundelwall-Thoren, 2007).  The test was administered in a sound booth via loudspeaker at a 0-degree azimuth, at 70dBHL for most subjects.  The QuickSIN yields an SNR loss score, which indicates the increase in SNR required to achieve a performance threshold. Larger SNR loss scores represent poorer performance.

Correlations were calculated to examine the relations among working memory, age, degree of hearing loss and speech-in-noise performance.  Not surprisingly, increases in age and degree of hearing loss were associated with poorer scores on the QuickSIN test. Working memory scores were also significantly correlated with aided QuickSIN scores.  Lower working memory scores were loosely associated with increased age and poorer unaided QuickSIN scores, but these relationships did not reach significance.

Reading span test scores, representing working memory, ranged from 17% to 50%, with a mean of 34%.  As in previous studies, subjects were divided into high and low working memory groups, based on the median score for the group. For slower compression speeds, comparable performance was achieved by both high and low working memory groups. At faster compression speeds, individuals in the high working memory group performed better than those in the low working memory group. For the fastest compression times, the difference in SNR loss between the high and low working memory groups was greater than 5dB. The authors point out that this is a substantial difference, as a QuickSIN SNR loss difference of 2.7dB is considered significant.

Aided QuickSIN scores were significantly affected by working memory for fast compression speed, but not for slow compression speed. There was high variability in the scores, especially for slow compression times, so further analysis was conducted to examine the contributions of other variables. For fast compression speeds, working memory and hearing loss accounted for most of the variance. For slow compression speeds, age and hearing loss were significant predictors of performance, but working memory was not.

The results of this study are consistent with previous reports suggesting that listeners with low working memory may not perform well with fast acting compression, whereas those with high working memory can be expected to do better.  The findings of the current study appear particularly robust because they emerged under less controlled conditions than in the laboratory studies. The authors point out that even in the hearing aid that allowed manipulation of compression speed, changing it resulted in other changes in signal processing as well.  The fact that compression speed still had a significant effect on speech-in-noise performance under these conditions is support for its relationship with working memory.

Though further study is needed to illuminate the relationship between working memory and the selection of hearing aid parameters, there are a number of potential benefits to incorporating working memory tests into clinical practice. The working memory assessment could help to explain poor performance with a current set of hearing aids and indicate the need for new aids or adjustments to signal processing parameters, if possible. Souza and Sirow offer a cautionary statement regarding the use of working memory assessment during a diagnostic hearing evaluation. They suggest that patients may not understand the link between auditory assessment and a task that could involve assessment of memory. With that cautionary consideration, hearing care providers may be more likely than other clinical professionals to recognize symptoms of cognitive decline. Atypical results of a working memory assessment may provide insight into a patient’s performance with hearing aids as well as their general cognitive health, prompting referrals to a primary care physician or other specialists.

The study of hearing loss, hearing aids, cognition and memory is an interesting area of inquiry with potentially important implications for clinical hearing aid fitting. Souza and Sirow’s report on the relationship between working memory and compression speed illustrates how individual variability in working memory could have specific impact on the selection of hearing aid characteristics.  Their findings represent an important link between laboratory investigation on this topic and the clinical prescription of hearing aids.

References

Baddeley, A. (1992). Working memory. Science 255 (5044), 556-559.

Foo, C., Rudner, M., Ronnberg, J. & Lunner, T. (2007). Recognition of speech in noise with new hearing instrument compression release settings requires explicit cognitive storage and processing capacity. Journal of the American Academy of Audiology 18(7), 618-631.

Gatehouse, S., Naylor, G. & Elberling, C. (2006). Linear and nonlinear hearing aid fittings: 2. Patterns of candidature. International Journal of Audiology 45(3), 153-171.

Jenstad, L. & Souza, P. (2005). Quantifying the effect of compression hearing aid release time on speech acoustics and intelligibility. Journal of Speech, Language and Hearing Research 48(3), 651-667.

Jenstad, L. & Souza, P. (2007). Temporal envelope changes of compression and speech rate: combined effects on recognition for older adults. Journal of Speech, Language and Hearing Research 50(5), 1123-1138.

Killion, M., Niquette, P., Gudmundsen, G., Revit, L. & Banerjee, S. (2004). Development of a quick speech-in-noise test for measuring signal-to-noise ratio loss in normal-hearing and hearing-impaired listeners. Journal of the Acoustical society of America 116(4), 2395-2405.

Lunner, T. (2003). Cognitive function in relation to hearing aid use. International Journal of Audiology 42 (Suppl.): S49-S58.

Lunner, T. & Sundewall-Thoren, E. (2007). Interactions between cognition, compression and listening conditions: effects on speech-in-noise performance in a two-channel hearing aid. Journal of the American Academy of Audiology 18(7), 604-617.

Ohlenforst, B., Souza, P. & MacDonald, E. (2014). Interaction of working memory, compressor speed and background noise characteristics. Paper presented at the American Auditory Society, Scottsdale, AZ.

Remensnyder, L. (2012). Audiologists as gatekeepers and it’s not just for hearing loss. Audiology Today, July/August,  24-31.

Ronnberg, J., Rudner, M., Foo, C. & Lunner, T. (2008 ). Cognition counts: a working memory system for ease of language understanding (ELU). International Journal of Audiology 47(Suppl. 2), S99-105.

Ronnberg, J., Lunner, T., Zekveld, A., Sorqvist, P., Danielsson, H., Lyxell, B. & Rudner, M. (2013). The Ease of Language Understanding (ELU) model: theoretical, empirical and clinical advances. Frontiers in Systems Neuroscience 7, 31.

Rudner, M., Foo, C., Ronnberg, J. & Lunner, T. (2009). Cognition and aided speech recognition in noise: specific role for cognitive factors following nine-week experience with adjusted compression settings in hearing aids. Scandinavian Journal of Psychology 50(5), 405-418.

Salthouse, T. (1994). The aging of working memory. Neuropsychology 8(4), 535-543.

On the prevalence of hearing loss and barriers to hearing aid uptake

Dawes, P., Fortnum, H., Moore, D., Emsley, R., Norman, P., Cruickshanks, K., Davis, A., Edmondson-Jones, M., McCormack, A., Lutman, M. & Munro, K.  (2014) Hearing in middle age: a population snapshot of 40- to 69-year olds in the United Kingdom. Ear & Hearing 35 (3), 44-51.

This editorial discusses the clinical implications of an independent research study and does not represent the opinions of the original authors.

The Biobank is a national program in the United Kingdom, aimed at longitudinal investigation of the prevention, diagnosis and treatment of diseases and health conditions affecting middle-aged individuals. Since 2006, the Biobank has recruited over half a million participants, who complete test procedures, provide biomedical samples and detailed health information and have their health followed over time, periodically providing updated information. One of the health conditions assessed in the Biobank study is hearing loss and over 160,000 participants have completed questionnaires, audiometric assessment and speech-in-noise testing.

Dawes and his colleagues used Biobank data to examine the prevalence of hearing impairment among 164,700 middle-aged respondents in the U.K., “hearing impairment” was defined as reduced or poor performance on a speech recognition in noise test. They assessed how audiologic and demographic factors relate to hearing impairment and the use of hearing aids among individuals in this age group.

For the Biobank database, hearing loss was assessed via audiometric testing and questionnaires covering lifestyle, environment and medical history, including associated symptoms such as tinnitus. Speech recognition in noise was assessed via the Digit Triplet Test (DTT; Smits et al., 2004). The DTT is a large-scale screening tool that can be administered via the telephone and internet.  The test includes 15 sets of monosyllable digit triplets, presented at a comfortable listening level. Noise levels are varied adaptively to arrive at the SNR required for 50% recognition. Speech recognition results were analyzed in relation to several demographic variables: age, work and music related noise exposure socioeconomic status, ethnicity and gender. 

10.7 % of participants had hearing impairment, as measured by the DTT. Tinnitus was reported by 16.9% of the subjects, which is consistent with previous reports (Davis 1995).  The results show, not surprisingly, that the prevalence of hearing loss increases with increasing age, with an acceleration of prevalence beginning in the 55-59 year old age group. The increase in prevalence with increasing age is consistent with previously published reports for this age group (Plomp & Mimpen, 1979; Wilson & Strouse, 2002; Smits et al., 2006). Tinnitus showed a more consistent increase with increasing age, without a steeper increase for respondents in their 50’s.  Hearing aid use was only 2% for the entire sample and increased with age.  Only 21% of the participants with Poor DTT scores reported using hearing aids.  Those who did use hearing aids had significantly higher socioeconomic status than those without hearing aids.

Only 2.0% of the middle-aged individuals in this study reported hearing aid use. This is similar to an earlier report in which hearing aid use for 41-70 year olds was 2.8% (Davis, 1995). The persistently low proportion of hearing aid use contrasts with the fact that 9.4% of the respondents in the current study had average pure tone thresholds of at least 35 dBHL in the better ear. There are many potential explanations for the low proportion of hearing aid use among hearing impaired individuals. Cost is a commonly cited explanation, though cost is not likely to have influenced the present report, as hearing aids are provided free in the United Kingdom and the participants included in this report probably did not purchase their hearing aids privately. Insufficient value and uncomfortable fit have also been reported as explanations for low hearing aid use (McCormack & Fortnum, 2013). Other proposed barriers to hearing aid use are related to motivation, expectations and attitudes toward hearing aids, with self-recognition of hearing handicap being the most consistently related factor to hearing aid use (Vestergaard-Knudsen et al., 2010).

One mechanism for addressing the concern of hearing aid cost is through the unbundling of the hearing aid and services provided. Bundled pricing (the packaging of hearing aid and services into one price) is typical in the U.S. Unbundling may encourage initial uptake because it allows hearing aid users to pay less at the outset and divide additional expenditures into smaller, more manageable amounts, paying fees at each visit after the initial service period. There is some concern that unbundled pricing will make hearing aid users less likely to obtain needed care, but this fear may be overstated. Hearing aid users generally indicate that verification measures and counseling increase satisfaction and perceived value of hearing aids (Kochkin, 2010; 2011), so follow-up care can be perceived by the patient as a valuable part of the rehabilitative process. Unbundling offers the additional benefit for private practices because fee-for-service appointments lead to more consistent monthly cash flow than bundled fees in which a large initial payment is received with free services for a long time thereafter.

The manner in which hearing aids are represented to the general public may further impact uptake. Hearing aids are best positioned as medical devices, prescribed by skilled professionals, in clinical settings where testing is performed in controlled acoustic environments. If price is prioritized, then testing, verification and follow-up care may be abbreviated to control costs. If cosmetic appeal is prioritized, patients may select the smallest devices, perhaps without adequate venting or directional microphones, though this might not be the best option for their loss and listening needs. The potential outcome of both scenarios is disappointment with the performance and comfort of the hearing instruments, resulting in either lack of use or return for credit.  Instead, hearing aid users need to be fully educated about the options that are available and counseled as to why some models are better for their needs than others. This cannot be achieved in an environment that emphasizes price over functionality and service.

As Dawes points out, hearing impairment may be better defined by speech recognition ability in everyday situations, rather than pure tone audiometry. Even so, it is arguable whether either of these measures alone should be used to define hearing aid candidacy. Instead, clinicians gain more insight into their patients’ motivation and readiness by examining how the hearing loss affects their ability to function in their regular activities. A mildly-impaired individual with a quiet, socially inactive lifestyle is less likely to be motivated for hearing aids than a similarly impaired individual who works full time and has an active social life. A thorough patient history and needs assessment, coupled with objective testing can more accurately identify hearing aid candidates than relying on degree of hearing loss alone. The authors of this article cite a study of Swiss hearing aid use and satisfaction, stating that in Switzerland, hearing aid candidacy is “based on the degree of social and emotional handicap due to hearing loss” and that the dispensing process focuses on ongoing counseling and care after the fitting.  This study reported high rates of long-term hearing aid use and satisfaction, where 97% of Swiss hearing aid owners reported using their hearing aids and only 3% were non-users (Bertoli, 2009).

It makes sense to advise unmotivated individuals to assess their difficulties, making note of every time they ask for repetition, misunderstand a word or sentence, or smile and “fake” their way through a conversation. I instruct patients to consider whether their hearing loss causes them to avoid places or situations that they might otherwise enjoy or if the hearing loss affects their ability to perform important work-related or social activities.  With a little patience and attention, most people can determine the point at which they are ready to proceed with a hearing aid purchase. Self-recognition of need is strongly associated with eventual hearing aid uptake and use (Vestergaard-Knudsen et al., 2010), meaning that a person who returns for a consultation after taking time to evaluate their difficulties is more likely to keep their hearing aids and follow through with proper use and care.

Even as testing techniques and prevalence data improve our ability to identify those with hearing impairment and those at risk, there remain barriers to hearing aid use. Consistent representation of hearing aids as medical devices that are fitted by clinical professionals may improve the perception and attitudes of the general public. Unbundled pricing may lower the cost barrier by making the initial purchase more affordable and concomitantly emphasizing the value of follow-up care. Finally, development and adherence to a thorough fitting protocol will ensure that those who do purchase hearing aids will receive a well-prescribed medical device and become an example of success to others.

 

References

Davis, A. (1995). Hearing in adults. London, United Kingdom: Whurr Publishers Ltd. XXX.

Davis, A., Smith, P., Ferguson, M. (2008).  Acceptability: benefit and costs of early screening for hearing disability: A study of potential screening tests and models. Health Technology Assessment 11 (42), 1-294.

Dawes, P., Fortnum, H., Moore, D., Emsley, R., Norman, P., Cruickshanks, K., Davis, A., Edmondson-Jones, M., McCormack, A., Lutman, M. & Munro, K.  (2014) Hearing in middle age: a population snapshot of 40- to 69-year olds in the United Kingdom. Ear & Hearing 35 (3), 44-51.

Department of Health (2001). Health Survey for England 1999: The health of minority ethnic groups. Retrieved from http://webarchiv.nationalarchives.gov.uk/+/www.dh.gov.uk/en/Publicationsandstatistics/Publications/PublicationsStatistics/DH_4009393.

Kochkin, S. (2010). MarkeTrak VIII: Customer satisfaction with hearing aids is slowly increasing. Hearing Journal 63(1), 11-19.

Kochkin, S. (2011). MarkeTrak VIII: Reducing patient visits through verification and validation. Hearing Review 18 (6), 10-12.

McCormack, A. & Fortnum, H. (2013). Why do people fitted with hearing aids not wear them? International Journal of Audiology 52, 360-368.

Plomp, R. & Mimpen, A. (1979). Speech reception threshold for sentences as a function of age and noise level. Journal of the Acoustical Society of America 66, 1333-1342.

Smits, C., Kapteyn, T. & Houtgast, T. .(2004). Development and validation of an automatic speech-in-noise screening test by telephone. International Journal of Audiology 43, 15-28.

Smits, Kramer, S. & Houtgast, T. (2006). Speech reception thresholds in noise and self-reported hearing disability in a general adult population. Ear and Hearing 27, 538-549.

Vestergaard-Knudsen, L., Oberg, M. & Nielsen, C. (2010). Factors influencing help seeking, hearing aid uptake, hearing aid use and satisfaction with hearing aids: A review of the literature. Trends in Amplification 14, 127-154.

Wilson, D. & Strouse, A. (2002). Northwestern University Auditory Test No. 6 in multi-talker babble: A preliminary report. Journal of Rehabilitation Research and Development 39, 105-113.

The most important factors behind directional microphone benefit

Keidser, G., Dillon, H., Convery, E. & Mejia, J. (2013). Factors influencing individual variation in perceptual directional microphone benefit. Journal of the American Academy of Audiology 24, 955-968.

This editorial discusses the clinical implications of an independent research study and does not represent the opinions of the original authors.

Understanding conversation in noisy environments is one of the most common difficulties for individuals with hearing loss. Counseling and training in communication strategies can help listeners with hearing loss make use of supplemental cues to improve speech understanding in noise. However, no hearing aid feature or clinical intervention is as likely to improve the ability to function in noise as directional microphones. Directional microphones, usually twin microphone designs, offer small but helpful increases in the signal-to-noise ratio, facilitating more comfortable listening and an improved ability to understand speech and function in noisy everyday situations.

Directionality consistently demonstrates benefits to speech perception performance in laboratory studies but the amount of directional benefit achieved by subjects is highly variable, even in studies with similar methods and procedures (Freyaldenhoven et al., 2005). A number of factors have been studied and reports have indicated that variability in directional benefit was unrelated to age (Wu, 2010; O’Brien et al, 2009), degree or configuration of hearing loss (Jesperson & Olsen, 2003; Ricketts & Mueller, 2000) or vent size (Ricketts, 2000; O’Brien et al, 2009). Furthermore, laboratory studies may not always predict everyday performance (Walden et al., 2000; Cord et al., 2002; Cord et al., 2004) so it is unclear how numerous factors could converge to affect individual directional benefit in everyday hearing aid use.

Recently emerging evidence has suggested that cognitive capacity may affect a listener’s ability to make use of directional benefits. Working memory affected hearing aid users’ performance with regard to different compression time constants (Gatehouse et al., 2003; Cox & Xu, 2010) and spatial separation ability (Neher et al., 2009). Dawes et al (2010) reported that differences in hearing aid benefit were partly determined by performance on speed of processing, selective attention and switching tasks. Humes (2007) further reported that cognition may affect individual speech perception abilities in noise. Though cognition declines with age, the changes vary tremendously across individuals and cannot be predicted by age alone (Glisky, 2007), so age and cognition, though related, may affect hearing aid use and speech perception in different ways.

The primary goal of Keidser et al’s study was to investigate the factors that contribute to variability in perceptual directional microphone benefit as measured in the laboratory. Specifically, they were interested in the effects and interaction of three potential sources of variability: differences in the individual SNR achieved by physical directional benefit, differences in the ability to make use of SNR improvements and variability related to measurement error.

Fifty-nine subjects participated in the study. All had bilateral, mild-to-moderate, sensorineural hearing loss.  Age ranged from 54 to 91 years, with an average of 74 years. Of the 59 subjects, 51 had experience with amplification, whereas 8 had never worn hearing aids. For the purpose of the study, subjects were fitted with binaural, behind-the-ear hearing aids with dual-microphones and wide dynamic range compression. Advanced signal processing such as noise reduction and adaptive directionality was turned off. Hearing aids were programmed according to NAL-NL2 targets and had two programs: omnidirectional and directional.

Participants attended two experimental sessions. At the first session, subjects completed cognitive testing. First, they were administered subtests of the Test of Everyday Attention (TEA; Robertson et al., 1996) which uses real-life scenarios to measure auditory selective attention and speed of processing. Working memory was assessed using the Reading Span Test (RST; Daneman & Carpenter, 1980).  In the RST, sentences are presented on a computer screen and subjects indicate whether the sentence was meaningful or not, subjects must also recall either the first or last word of each sentence.

At the second session, hearing aids and earmolds were fitted and vent diameters were measured. The frequency range of amplification was measured, with the low frequency limit (f-amp) defined as the point at which real-ear insertion gain exceeded 3dB. The angle of the microphone ports was measured with reference to the loudspeaker axis. Speech in noise testing was completed, using the Australian Bamford-Kowal-Bench (BKB/A) sentences (Bench et al., 1979) in the presence of 8-talker babble from the NAL Speech and Noise for Hearing Aid Evaluation CD (Keidser et al, 2002). Speech was presented from a loudspeaker 1m in front of the subject. A constant level of uncorrelated multi-talker babble was presented from four loudspeakers surrounding the subject at a distance of 2m. Speech levels were adjusted to arrive at the SNR required to achieve 50% performance.

Following speech in noise testing, individual in-situ SNR levels were measured to determine how room acoustics may have affected hearing aid performance.  Individual 3D AI-DI measurements were obtained to ascertain the physical directional benefit for each subject in the test environment. The 3D AI-DI scores are directivity measurements weighted by the Articulation Index model, as measured in the center of a 3D array of 41 loudspeakers (Killion et al, 1998). In-situ SNR and 3D-AI-DI measures were computed for broadband (BB), low-frequency (LF, <2000Hz) and high-frequency (HF, >2000Hz) ranges.

Cognitive test scores were weakly correlated. The only auditory cognitive test, the ASA, was not correlated with audiological pure tone average (PTA) but was weakly correlated with age. For the physical measures, broadband (BB) and low-frequency (LF) in-situ SNRs were strongly correlated with each other. The low-frequency limit or f-amp, was highly correlated to the LF in-situ measures as well as to PTA and vent diameter. These correlations indicate that participants who had higher PTAs (more hearing loss) had smaller vent diameters, frequency responses extending further into the low-frequencies and more physical benefit from directional microphones at low frequencies.

The average perceptual directional benefit as measured by SRTn was 2.7dB, with a range from 0.3 to 5.3dB.  No participants showed negative effects of directionality.  When comparing benefit ranges in individual trials versus the mean of the three trials, effectively removing any variability attributable to random measurement errors, the range of benefit was reduced from around 9.2 dB to 5.0dB. Therefore, about half of the variation in directional microphone benefit was explained by measurement errors.  Variation in perceptual directional benefit was not correlated with age or configuration (slope) of hearing loss. Analysis of the cognitive and the in-situ measures of physical directionality showed that the only factors exerting a significant effect on perceptual benefit were LF 3D AI-DI, ASA scores and microphone angle.

With reference to the goals of their study, Keidser and her colleagues found that measurement error, physical directionality and the individual ability to make use of directional cues may contribute to variability in perceptual directional benefit. About half of the variability in measured perceptual directional benefit was attributable to measurement error associated with speech-in-noise testing. Measurement error could include head movements during testing causing brief head shadow effects, problems with speech test list equivalence (Dillon, 1982) and potential practice effects. The authors suggest that multiple measurements of perceptual directional benefit, in each test condition, should always be carried out in order to mitigate the effects of measurement error.

In agreement with previous reports, there was no direct relation between perceptual directional benefit and age, PTA or configuration of hearing loss, though there was a relation to vent diameter. Greater perceptual directional benefit was derived when greater physical directivity was achieved in the low frequencies, which was related to decreased vent diameter. This result is in agreement with previous work showing increased directional benefit with more occluded molds as compared to more open fittings (Ricketts, 2000; Fabry, 2006; Klemp & Dhar, 2008).

A more upward-pointing microphone angle was associated with improved perceptual directional benefit. This is in agreement with a report by Ricketts (2000) that showed increased physical directivity as microphone angle exceeded 20 degrees from the horizontal plane. The effect of microphone angle in the current study was small, accounting for only 4% of the variation. Because the interaction of microphone angle with other hearing aid and environmental characteristics is unknown, the authors do not recommend that clinicians deliberately fit hearing aids with microphones pointing upward.

The outcomes of this study emphasize the importance of low-frequency amplification to achieve optimal directional benefit. The lower limit of the amplification range as well as vent diameter have an effect on physical directivity that affects the perceptual benefit that can be derived from directionality. Thus, it is of particular importance for clinicians to not only select appropriate venting characteristics for each individual, but to ensure that the range of amplification is set in a manner that accounts for venting effects. Programming software requires the entry of acoustic parameters to guide frequency response characteristics, especially in the low frequency range; failure to enter the correct acoustic properties risks over or under amplifying the low-frequency range.

Of course there are many factors to consider when choosing venting, gain and output characteristics, but achieving optimal directional benefit should be considered among them.  Equalizing low-frequency gain in a directional program for use in noise may be advisable to achieve better directivity, but conversely, reduction of low-frequency gain in noise programs may be more comfortable and therefore more desirable for hearing aid users. Careful consideration of the way in which these variables interact for each individual is critical to their success with hearing aids in their daily activities.

 

References

Bench, R., Doyle, J., Daly, N. & Lind, C. (1979). The BKB/A Speech Reading (Lipreading) Test. Victoria: La Trobe University.

Cord, M., Surr, R., Walden, B. & Olson, L. (2002). Performance of directional microphone hearing aids in everyday life. Journal of the American Academy of Audiology 13 (6), 295-307.

Cord, M., Surr, R., Walden, B. & Dyrlund, O. (2004). Relationship between laboratory measures of directional advantage and everyday success with directional microphone hearing aids. Journal of the American Academy of Audiology 15(5), 353-364.

Cox, R. & Xu, J. (2010). Short and long compression release times: speech understanding, real world preferences and association with cognitive ability. Journal of the American Academy of Audiology 21(2), 121-138.

Daneman, M. & Carpenter, P. (1980). Individual differences in working memory and reading. Journal of Verbal Learning and Verbal Behavior 19(4), 450-466.

Dawes, P., Munro, K., Kalluri, S., Nooraei, N. & Edwards, B. (2010). Older adults, hearing aids and listening effort. Paper presented at IHCON, August 11-15, Lake Tahoe.

Dillon, H. (1982). A quantitative examination of the sources of speech discrimination test score variability. Ear and Hearing, 3(2), 51-58.

Fabry, D. (2006). Facts vs. myths: the “skinny” on open-fit hearing aids. Hearing Review 13, 20-25.

Freyaldenhoven, M., Nabelek, A., Burchfield, S. & Thelin, J. (2005). Acceptable noise level as a measure of directional hearing aid benefit. Journal of the American Academy of Audiology 16(4), 228-236.

Gatehouse, S., Naylor, G. & Elberling, C. (2003). Benefits from hearing aids in relation to the interaction between the user and the environment. International Journal of Audiology 42 (Suppl. 1), S77-S85.

Glisky, E. (2007). Changes in cognitive function in human aging. In: Riddle DR, ed. Brain Aging: Models, Methods and Mechanisms. Boca Raton, FL: CRC Press, chpt. 1. www.ncbi.nlm.nih.gov/books/NBK3885.

Humes, L. (2007). The contributions of audibility and cognitive factors to the benefit provided by amplified speech to older adults. Journal of the American Academy of Audiology 18(7), 590-603.

Jesperson, C. & Olsen, S. (2003). Does directional benefit vary systematically with omnidirectional performance? Hearing Review 10, 16-24, 62.

Keidser, G., Ching, T. & Dillon, H. (2002). The National Acoustic Laboratories’ (NAL) CDs of Speech and Noise for Hearing Aid Evaluation: normative data and potential applications. Australian New Zealand Journal of Audiology 24(1), 16-35.

Keidser, G., Dillon, H., Convery, E. & Mejia, J. (2013). Factors influencing individual variation in perceptual directional microphone benefit. Journal of the American Academy of Audiology 24, 955-968.

Killion, M., Schulein, R. & Christensen, L. (1998). Real-world performance of an ITE directional microphone. Hearing Journal 51(4), 24-38.

Klemp, E. & Dhar, S. (2008). Speech perception in noise using directional microphones in open canal hearing aids. Journal of the American Academy of Audiology 19(7), 571-578.

Neher, T., Behrens, T. & Carlile, S. (2009). Benefit from spatial separation of multiple talkers in bilateral hearing aid users: effects of hearing loss, age and cognition. International Journal of Audiology 48 (11), 758-774.

O’Brien, A., McLelland, M. & Keidser, G. (2009). The Effect of Asymmetric Directionality on Speech Recognition in Noise. NAL Report 019. Sydney: National Acoustic Laboratories.

Ricketts, T. & Mueller, H. (2000). Predicting directional hearing aid benefit for individual listeners. Journal of the American Academy of Audiology 11(10), 561-569.

Ricketts, T. (2000). Directivity quantification in hearing aids: fitting and measurement effects. Ear and Hearing 21(1), 45-58.

Robertson, I., Ward, T., Ridgeway, V. & Nimmo-Smith, I. (1996). The structure of normal human attention: the Test of Everyday Attention. Journal of the International Neuropsychological Society 2(6), 525-534.

Walden, B., Surr, R., Cord, M., Edwards, B. & Olson, L. (2000). Comparison of benefits provided by different hearing aid technologies. Journal of the American Academy of Audiology 11(10), 540-560.

Wu, Y. (2010). Effect of age on directional microphone hearing aid benefit and preference. Journal of the American Academy of Audiology 21(2), 78-89.

 

Acclimatizing to hearing aids may not mean what you think it means

Dawes, P., Munro, K., Kalluri, S., & Edwards, B. (2014). Acclimatization to hearing aids. Ear and Hearing, Published Ahead-of-Print.

This editorial discusses the clinical implications of an independent research study and does not represent the opinions of the original authors.

New patients frequently report that their new hearing aids sound tinny, metallic, loud, or unnatural. The clinical audiologist recognizes that these comments will decrease in frequency with time. A process often described as acclimatization: a reaction to new hearing aids that occurs because the patient has adjusted to hearing sound filtered by their hearing loss. When amplification is introduced, the subsequent increase in audibility and loudness perception is unfamiliar and therefore unnatural.

A smooth transition to hearing aid use can be achieved through counseling prior to fitting, preparing the individual for a period of unnatural sound quality. At the fitting, the instruments can be set below prescribed target, allowing the listener a more comfortable period of adjustment. Most individuals will accept increased gains, approaching prescribed target over 2 or 3 months. Some patients, however, require a much longer period of acclimatization of one to two years (Keidser, et al., 2008).

In addition to changes in the preferred gain of new hearing aid users, other improvements due to acclimatization have been proposed: speech discrimination over time (Bentler, et al.1993a, Gatehouse, 1992), subjective benefit and sound quality over time (Bentler, et al., 1993b; Ovegard, et al., 1997) and loudness perception and intensity discrimination over time (Olsen, et al., 1999; Philibert et al., 2002). Most of these studies reported small but significant acclimatization effects; while others found no significant differences between new and experienced hearing aid users (Smeds et al, 2006a, 2006b).

Ultimately, there is little agreement on the definition of this effect and even less agreement in the methods that quantify these changes. A high degree of response variability is usually noted, indicating that several factors (degree, etiology, and configuration of hearing loss) may contribute to the adjustment that is experienced by new hearing aid users.

Dawes and his colleagues outlined a number of goals for their study:  First, they hoped to determine if there is an acclimatization effect for aided speech recognition with current, nonlinear hearing aids and if there is a difference between unilateral and bilateral fittings. Second, they wanted to know if new hearing aid users’ self-reports would indicate a period of acclimatization. Third, they sought to determine if acclimatization could be predicted by the degree of hearing loss, prior hearing aid use or cognitive capacity.

Forty-nine subjects participated in the study, recruited from four audiology clinics. There were 16 new unilateral hearing aid users, 16 new bilateral users and 17 experienced users, including 8 bilateral and 9 unilateral users. Experienced subjects used their own hearing aids and new users were fitted with BTE or CIC instruments with comparable circuit technology.  New instruments were fitted to NAL-NL1 targets and verified with real-ear measurements. Newly-fitted subjects had a few days of hearing aid use prior to commencement of the study and were allowed gain adjustments only if necessary due to discomfort with prescribed gain levels.

To measure speech recognition, a 4-alternative forced-choice procedure was used, in which listeners were asked to select one word from a closed set of four rhyming words, in response to the prompt, “Can you hear the word X clearly?” In addition to the speech recognition test, subjects completed the Spatial, Speech and Qualities of Hearing Questionnaire – Difference version (SSQ-D; Gatehouse & Noble, 2004), as well as two measures of cognitive processing. The SSQ-D was administered after 12 weeks and allowed the subjects to judge their own changes in performance and listening effort with the hearing aids over the course of the study.

Two cognitive tests were administered. The first, a visual reaction time task, required participants to watch digits presented on a computer monitor and press the corresponding numbers on a keypad as quickly as possible. Responses were scored as correct or incorrect and response times were measured in milliseconds. Working memory was also evaluated, using the Digits Backwards subtest from the Weschler Adult Intelligence Scale – III (WAIS-III; Wechsler, 1997).  Subjects listened to lists of digits and were asked to repeat them in reverse order. Lists increased in length as the test progressed and responses were correct if all digits were repeated in the correct order.

In all test conditions, variability was high and a small improvement was noted over time, likely due to practice effects. The mean SNR required to achieve 50% performance did not differ between new unilateral and new bilateral hearing aid users, but experienced users required significantly more favorable SNRs to achieve this level of performance, compared to new users. This was attributed to the older average age and poorer hearing thresholds of the experienced user group.

For the new user groups, if acclimatization occurred it was expected that performance would improve in aided conditions over time. Instead there were small trends of improvements in unaided and aided conditions. For unilateral users, the trend was noted in the fitted ear, whereas for bilateral users, small improvements were noted for both ears.  Of all the variables studied, the only one to have a significant effect on performance was time, which yielded a small consistent improvement across groups and listening conditions.  When place, manner and voicing errors were analyzed, there was no significant difference for type of error, nor was there a significant interaction with the other variables of group, aiding, ear or presentation level.

Because of the high variability in responses, correlations were measured for effects of hearing aid usage, degree of hearing loss, cognitive capacity, and a change in audibility referred to as “stimulus novelty”. For new hearing aid users, there was no significant correlation between the change speech recognition scores, severity of hearing loss, cognitive test score, or hearing aid variables. Older age was only correlated with slower reaction time scores and a higher amount of time spent in quiet conditions. There were no significant correlations for SSQ-D scores and change in aided performance in any of the listening conditions. Disparate SSQ-D scores did indicate that new hearing aid users perceived improvements over the course of the study, whereas experienced users did not.

Though there were small increases in speech recognition performance over time in all conditions, this was consistent with a practice effect and was not taken as evidence for acclimatization. Self-reports from the SSQ-D showed that new users experienced improvements with amplification that were significantly greater than those reported for experienced users. It is not surprising that SSQ-D scores might still show improvement, as the SSQ-D probes subjective perceptions of performance, including listening effort and sound quality. These elements may well improve with consistent use of new hearing aids even if actual speech recognition has not changed significantly. Improved audibility may allow the listener to function well in everyday environments with significantly less effort, making a positive impression on the listener, more so than small but measurable improvements in word recognition.

Another potential explanation for the lack of agreement between objective and subjective measures in this study could be related to the actual comparison that was made by the subjects when the responded to the SSQ-D items.  Because new users probably experienced noticeable benefits from the hearing aids, they may have had trouble comparing their performance immediately post-fitting versus 12 weeks later and may have inadvertently compared pre-fitting and post-fitting performance, yielding a larger SSQ-D score.

Though the results of this study did not support an acclimatization effect for speech recognition, they do not rule out the existence of acclimatization altogether. Preferred gain, perceived listening effort, and sound quality improvements, among other effects, may well occur for most new hearing aid users, to varying degrees based on degree of hearing loss, duration of prior hearing loss and prior experience with hearing aids.

The subjects in this study were fitted with either BTE or CIC hearing aids but the hearing aid style was not examined with regard to acclimatization. CIC users often experience occlusion and adjustment to their own voices in the early days of hearing aid use; much more so than BTE users who probably have less occlusion than commonly found with CIC hearing aids. Whether this could have an impact on speech recognition acclimatization is questionable, but it could have affect subjective reports. Similarly, individuals using hearing aid features such as frequency-lowering or wireless routing of signal may demonstrate other perceptual learning or acclimatization effects.

Perhaps the greatest finding of this study was the contrast between measurable outcomes in the domain of subjective spatial perception and traditional measures of speech recognition. Many failed attempts to document acclimatization have focused on speech recognition or loudness perception rather than probing the patient’s perception of their acoustic environment—something achieved with the SSQ-D. The apparent sensitivity of this measure should direct future experimental design in this area. For the practicing clinician, this contrast can aid in developing counseling approaches: it’s clear that speech recognition won’t change over time, but the complexity or overwhelming nature of the acoustic environment may become simpler with time.

References

Bentler, R.A., Niebuhr, D.P., Getta, J.P. & Anderson, C.V. 1993a. Longitudinal study of hearing aid effectiveness. I. Objective measures.  Journal of Speech and Hearing Research 36, 808-819.

Gatehouse, S. 1992. The time course and magnitude of perceptual acclimatization to frequency responses: Evidence from monaural fitting of hearing aids. Journal of the Acoustical Society of America 92, 1258-1268.

Gatehouse, S. & Noble, W. (2004). The Speech, Spatial and Qualities of Hearing Scale (SSQ). International Journal of Audiology 43, 85-99.

Keidser, G., O’Brien, A., Carter, L., McLelland, M., and Yeend, I. (2008). Variation in Preferred Gain with Experience for Hearing-Aid Users.  International Journal of Audiology 47 (10), 621 – 635.

Munro, K.J. & Lutman, M.E. 2003. The effect of speech presentation level on measurement of auditory acclimatization to amplified speech.  Journal of the Acoustical Society of America, 114, 484-495.

Ovegard, A., Lundberg, G., Hagerman, B., Gabrielsson, A., Bengtsson, M. 1997. Sound quality judgment during acclimatization of hearing aid. Scandinavian Audiology, 26, 43-51.

Palmer, C.V., Nelson, C.T. & Lindley, G.A. 1998. The functionally and physiologically plastic adult auditory system. Journal of the Acoustical Society of America, 103, 1705-1721.

Philibert, B., Collet, L., Vesson, J.F. & Veuillet, E. 2002. Intensity-related performances are modified by long-term hearing aid use: A functional plasticity? Hearing Research, 165, 142-151.

Philibert, B., Collet, L., Vesson, J.F. & Veuillet, E. 2005. The auditory acclimatization effect in sensorineural hearing-impaired listeners: Evidence for functional plasticity. Hearing Research, 205, 131-142.

Ronnberg, J., Rudner, M. & Foo, C. (2008). Cognition counts: A working memory system for ease of language understanding (ELU). International Journal of Audiology 47 (Suppl 2), S99-105.

Saunders, G.H. & Cienkowski, K. (1997). Acclimatization to hearing aids. Ear and Hearing 18, 129-139.

Smeds, K., Keidser, G., Zakis, J., Dillon, H., Leijon, A. 2006a. Preferred overall loudness. I. Sound field presentation in the laboratory. International Journal of Audiology, 45, 12-25.

Smeds, K., Keidser, G., Zakis, J., Dillon, H., Leijon, A. 2006b. Preferred overall loudness. II. Listening through hearing aids in field and laboratory tests. International Journal of Audiology, 45, 12-25.

Taubman, L., Palmer, C. & Durrant, J. (1999). Accuracy of hearing aid use time as reported by experienced hearing aid wearers. Ear and Hearing 20, 299-305.

Wechsler, D. (1997). Wechsler Adult Intelligence Scale (3rd ed.) Oxford: Pearson Assessment.

Willott, J.F. 1996. Physiological plasticity in the auditory system and its possible relevance to hearing aid use, deprivation effects, and acclimatization. Ear and Hearing, 17, 66S-77S.

Yund, E.W., Roup, C.M. & Simon, H.J. (2006). Acclimatization in wide dynamic range multichannel compression and linear amplification hearing aids.  Journal of Rehabilitation Research and Development 43, 517-536.

Should you prescribe digital noise reduction to children?

Pittman, A. (2011). Age-related benefits of digital noise reduction for short term word learning in children with hearing loss. Journal of Speech, Language and Hearing Research 54, 1448-1463.

This editorial discusses the clinical implications of an independent research study and does not represent the opinions of the original authors.

A child’s ability to learn new words has important implications for language acquisition, mental and social development as well as academic achievement.  How easily a child acquires new vocabulary words can be affected by numerous factors, including age, working memory and current vocabulary (Alt, 2010). Hearing loss is known to adversely affect children’s ability to learn new words and the more severe the loss, the more significant the effect on word learning (Pittman, et al., 2005; Blamey et al., 2001). The effect of hearing loss on word learning may be related to a decreased ability to encode the degraded stimuli into working memory. Indeed, in a study with normal-hearing and hearing-impaired children, Pittman found that word stimuli that were modified with narrowed bandwidths were harder for children to learn (Pittman, 2008). Similar results indicating that degraded perception adversely affects children’s phonological processing have been reported elsewhere (Briscoe, et al., 2001).

In many everyday listening situations, speech must be perceived in the presence of noise or other competing sounds. Noise can degrade the speech information, making words more difficult to encode into working memory and identify correctly. Individuals with hearing loss are more adversely affected by the presence of background noise (Kochkin, 2002; McCoy et al., 2005; Picou et al., 2013), which is of particular concern when the effects of noise on word learning are considered. Hearing aids can at least partially mitigate effects of background noise with the use advanced signal processing like directional microphones and digital noise reduction (DNR). However, little evidence exists to support beneficial effects of DNR on word learning. Pittman suggests that there is reason for concern as DNR could impose negative effects on word learning because of reductions in overall amplification. Additionally, the effect of DNR on connected speech, which offers semantic and syntactic context, may be very different than the effects on isolated word learning, so the everyday experience of hearing aid users could be different from laboratory results that measured perception of isolated words.

This study examined how DNR affects word learning in hearing-impaired children with hearing aids. The authors presented these hypotheses:

1)              Word learning would decrease in noise for children with normal hearing and those with hearing loss.

2)              Word learning rates would slow in noise, due to the reduction in overall amplification imposed by DNR.

Forty-one children with normal hearing and 26 participants with mild-to-moderate hearing loss participated in the study. The treatment groups were comprised of two age sub-groups: a younger group of children from age 8-10 and a slightly older group of children from age 11-12. The children with hearing loss had been diagnosed at an average age of approximately 3 years and all but one wore personal hearing aids. Participants with hearing loss were fitted with BTE hearing aids programmed to DSL v5.0 targets, verified with real-ear measures and set with two programs. In Program 1, advanced signal processing features like noise reduction, impulse reduction, wind noise reduction and feedback management were turned off. In Program 2, these features remained disabled except for noise reduction, which was set to maximum.

Word learning was tested using nonsense words, presented in three sets of five words each. All were two-syllable words and each list contained words with the same vowels in the first and last syllables. Stimuli were presented in sound field by a female talker at a level of 50dB SPL and SNR of 0dB. Children were seated at a small table about one meter away from the speaker. Nonsense words were presented on a computer screen, along with five pictures of nonsense objects categorized as toys, flowers or aliens. The children were asked to select the appropriate picture to go with the word and were given positive reinforcement for selecting the correct picture. No reinforcement was provided for selecting the wrong picture. Children therefore learned the new words via a process of trial and error.

The first goal of the study was to examine the impact on noise on children’s word learning ability. Statistical analyses indicated that NH participants learned words faster than the HL participants did, older children learned faster than younger children and learning in quiet was faster than learning in noise. The presence of noise resulted in further decrements in performance for HL listeners, indicating that noise had a more deleterious effect on word learning in noise for participants with hearing loss than it did for normally hearing participants.

The second goal of the study was to determine if DNR affected word learning for children with hearing loss. When DNR trials were compared to quiet and noise trials, younger children performed the same in noise whether or not they were using DNR in their hearing aids. Performance for both noise conditions was significantly poorer than performance in quiet. In contrast, the performance of older participants improved with DNR, with DNR performance closely approximating performance in quiet.

When results from the word learning task were examined with reference to Peabody vocabulary scores, the results indicated that participants with hearing loss had lower vocabulary ages than the normally hearing participants. For the experimental tasks, normally hearing participants required fewer trials to reach 70% performance than the participants with hearing loss. Further analysis revealed that the age of identification, age of amplification and years of amplification use accounted for 85% of the variance, but follow-up tests revealed significant relations between word learning and age, but not word learning and hearing history. These results suggest that despite individual variability, word learning in noise was most related to the factors of age and vocabulary.

In sum, the results of this investigation suggest that DNR did not have an effect, positive or negative, on younger participants. It did improve performance for older children, however, regardless of their hearing history or years of amplification. The author points out that childrens’ speech perception in noise is known to improve with age (Elliott, 1979; Scollie, 2008) but the participants in this study demonstrated age effects only when DNR was used. It appears that the combination of DNR and greater vocabulary knowledge allowed the older listeners to demonstrate superior word learning.

There are many factors to consider when prescribing amplification characteristics for children. Word learning is a critical developmental process for children, with important implications for future social and academic accomplishments.  The documented beneficial effects of DNR on word learning in complex listening environments could be a strong motivator for selection in a pediatric hearing aid. In addition to potential word learning benefits, DNR could make amplification more comfortable in noisy conditions, thereby increasing the acceptance of hearing aids and expanding potential opportunities for communication and further word learning.

Some caution should be voiced in the selection of DNR for pediatric use. Many of these algorithms reduce frequency-specific hearing aid gains, presenting the opportunity to compromise audibility of some speech sounds when listening in noise. Prior to consideration of any DNR algorithm in pediatric populations, data should be presented that ensure the maintenance of speech audibility when that particular DNR algorithm is active and noise is presented at a levels typical of the child’s academic setting (see: Stelmachowicz et al., 2010).

The outcomes reported here provide general support for the use of DNR in school-age children. It must be clarified that the documented benefits do not suggest improved speech understanding, as this is not a function of the algorithm. Rather, the documented improvements in word learning most likely arise from the fact that noise in the absence of speech was reduced in level, reducing the effort required to listen to the individual words as they were presented.

For additional information on the prescription of hearing aid signal processing features in pediatric populations, please reference the 2013 Pedatric Amplification Guidelines, published by the American Academy of Audiology: http://audiology.org/resources/documentlibrary/Documents/PediatricAmplificationGuidelines.pdf

 

References

Alt, M. (2010). Phonological working memory impairments in children with specific language impairment: Where does the problem lie? Journal of Communication Disorders 44, 173-185.

Bentler, R., Wu, Y., Kettel, J. & Hurtig, R. (2008). Digital noise reduction: Outcomes from laboratory and field studies. International Journal of Audiology 47, 447-460.

Blamey, P., Sarant, J., Paatsch, L., Barry, J., Bow, C., Wales, R. & Rattigan, K. (2001). Relationships among speech perception, production, language, hearing loss and age in children with impaired hearing. Journal of Speech, Language and Hearing Research 44, 264-285.

Briscoe, J., Bishop, D. & Norbury, C. (2001). Phonological processing, language and literacy: a comparison of children with mild-to-moderate sensorineural hearing loss and those with specific language impairment. Journal of Child Psychology and Psychiatry and Allied Disciplines 42, 329-340.

Dunn, L. & Dunn, L. (2006). Peabody Picture Vocabulary Test – III. Circle Pines, MN:AGS.

Kochkin, S. (2002). MarkeTrak VI: 10-year customer satisfaction trends in the US hearing instrument market. The Hearing Review 9 (10), 14-25, 46.

McCoy, S.L., Tun, P.A. & Cox, L.C. (2005). Hearing loss and perceptual effort: downstream effects on older adults’ memory for speech. Quarterly Journal of Experimental Psychology A, 58, 22-33.

Picou, E.M., Ricketts, T.A. & Hornsby, B.W.Y. (2013). How hearing aids, background noise and visual cues influence objective listening effort. Ear and Hearing 34 (5).

Pittman, A., Lewis, D., Hoover, B. & Stelmachowicz, P. (2005). Rapid word learning in normal-hearing and hearing-impaired children. Effects of age, receptive vocabulary and high-frequency amplification. Ear and Hearing 26, 619-629.

Pittman, A. (2008).  Short-term word learning rate in children with normal hearing and children with hearing loss in limited and extended high-frequency bandwidths. Journal of Speech, Language and Hearing Research 51, 785-797.

Pittman, A. (2011). Age-related benefits of digital noise reduction for short term word learning in children with hearing loss. Journal of Speech, Language and Hearing Research 54, 1448-1463.

Ng, E., Rudner, M., Lunner, T., Syskind Pedersen, M. & Rönnberg, J. (2013).  Effects of noise and working memory capacity on memory processing of speech for hearing aid users. International Journal of Audiology, Early Online: 1–9

Ricketts, T. & Hornsby, B. (2005). Sound quality measures for speech in noise through a commercial hearing aid implementing digital noise reduction. Journal of the American Academy of Audiology 16, 270-277.

Sarampalis, A., Kalluri, S. & Edwards, B. (2009). Objective measures of listening effort: effects of background noise and noise reduction. Journal of Speech Language and Hearing Research 52, 1230-1240.

Stelmachowicz, P., Lewis, D., Hoover, B., Nishi, K., McCreery, R. & Woods, W. (2010). Effects of digital noise reduction on speech perception for children with hearing loss. Ear and Hearing 31, 245-355.

The Top 5 Hearing Aid Research Articles from 2013!

1) The Clinical Practice Guidelines in Pediatric Amplification

After a 10-year wait, the guidelines for prescription of hearing aids to children were updated in 2013—making them the most modern of any peer-reviewed guidelines. There is little doubt that these recommendations will impact future publication and fitting protocols at clinical sites around the world. The guidelines are freely available at the link below.

American Academy of Audiology. (2013). Clinical Practice Guidelines Pediatric Amplification. Reston, VA: Ching, T., Galster, J., Grimes, A., Johnson, C., Lewis, D., McCreery, R…Yoshinago-Itano, C.

http://buff.ly/18TNGsz

2) Placebo effects in hearing aid trials are reliable

This article echoes publications from the early 2000’s (e.g., Bentler et al., 2003) that reported on blinded comparisons of analog and digital hearing aids. In those early studies, participants showed clear bias when primed to believe that option ‘A’ was a higher technology than option ‘B’. That early work was more focused on comparing technologies than this insightful report on placebo effects. Dawes and colleagues share an important reminder that placebo is real and should be accounted for in experimental design, whenever possible.

Dawes, P., Hopkins, R., & Munro, K. (2013). Placebo effects in hearing aid trials are reliable. International Journal of Audiology, 52(7), 472-477.

http://buff.ly/JF7DHM

3) Effects of hearing aid use on listening effort and mental fatigue

In the last few years, a number of research audiologists and hearing scientists have worked to document relationships between cognitive capacity, listening effort, and hearing aid use. An undertone of these efforts has been the assumption that a person with hearing loss will be less fatigued when listening with hearing aids. This article is one of the first published attempts at clearly documenting this fatiguing effect.

Hornsby, B.W. (2013). Effects of hearing aid use on listening effort and mental fatigue associated with sustained speech processing demands. Ear & Hearing, 34(5), 523-534.

http://buff.ly/JF7vrH

4) Characteristics of hearing aid fittings in infants and young children

The recent publication of updated pediatric fitting guidelines leads one to wonder how well fundamental aspects of these recommendations are being followed. This report from McCreery and colleagues is a clear indication that superior pediatric hearing care is uncommon and most often found in large pediatric medical centers. They also reinforce the consideration that consistent care from a single center may result in the most prescriptively appropriate hearing aid fitting.

McCreery, R., Bentler, R., & Roush, P. (2013). Characteristics of hearing aid fittings in infants and young children. Ear & Hearing, 34(6), 701-710.

http://buff.ly/18TNnhp

5) The Style Preference Survey (SPS): a report on psychometric properties and a cross-validation experiment

Closing out the Top 5: this article warrants high regard for rigor in design and quality of reporting. The authors delivered an article that will educate future researchers on the development and validation of questionnaires. Beyond this utility, the results are some of the first to identify the dimensions of preference that underlie the well-established bias toward preference of open-canal hearing aids.

Smith, S., Ricketts, T., McArdle, R., Chisolm, T., Alexander, G., & Bratt, G. (2013). Style preference survey: a report on the psychometric properties and a cross-validation experiement. Journal of the American Academy of Audiology, 24(2), 89-104.

http://buff.ly/JF740H

Do the benefits of tinnitus therapy increase with time?

Parazzini, M., Del Bo, L., Jastreboff, M., Tognola, G. & Ravazzani, P. (2011). Open ear hearing aids in tinnitus therapy: An efficacy comparison with sound generators. International Journal of Audiology, 50(8), 548-553.

This editorial discusses the clinical implications of an independent research study and does not represent the opinions of the original authors.

Tinnitus management can include a variety of treatment approaches but the most effective usually include a combination of counseling and sound therapy (Jastreboff, 1990; Jastreboff & Hazell, 2004). For many individuals with hearing loss and tinnitus, hearing aids may be the only tinnitus treatment they participate in. Specific treatment recommendations vary depending on a number of patient characteristics, such as degree of hearing loss and severity of the tinnitus disturbance.

Tinnitus Retraining Therapy (TRT; Jastreboff, 1995; Henry et al., 2002, 2003; Jastreboff & Jastreboff, 2006) is a widely known therapeutic approach using counseling and sound therapy, based on the neurophysiological model of tinnitus, that stresses the importance of helping individuals understand their condition, reducing awareness and attention to the tinnitus, providing or restoring appropriate auditory input and eventually training the auditory system to habituate to the tinnitus. Jastreboff & Hazell (2004) have proposed a classification system in which patients are assigned to one of five categories: 0 = mild or recent tinnitus, 1 = normal hearing and severe tinnitus, 2 = significant hearing loss, 3 = hyperacusis and 4 = prolonged worsening of tinnitus or hyperacusis following sound exposure. A patient’s classification on this scale can guide treatment recommendations thereafter. Counseling educates patients about their hearing loss and tinnitus, helping them cope with the stress and annoyance of tinnitus in their everyday lives. Sound therapy treatment aims to help patients habituate to their tinnitus, employing ear-level sound generators for individuals without hearing loss (category 1; described above) whereas hearing aids are recommended for tinnitus sufferers with significant hearing loss (category 2).

Individuals who fall into the borderline area between categories 1 and 2 could theoretically be treated with either sound generators or hearing aids. Presently, there is little evidence to suggest that one of these approaches is superior to the other. Therefore, the purpose of Parazzini et al.’s study was to compare the efficacy of sound therapy treatments with sound generators versus open-fit hearing aids for tinnitus patients whose characteristics fall between categories 1 and 2.

91 participants completed the study. All participants met the requirements for tinnitus categorization between Jastreboff categories 1 and 2, with pure tone thresholds equal to or less than 25dB HL at 2kHz and greater than or equal to 25dB at frequencies higher than 2kHz. None of the participants had used hearing aids or been treated with tinnitus retraining therapy prior to the study. Participants were randomly assigned to one of two treatment groups: those fitted with small, ear-level sound generators (SG group) and those fitted with binaural open fit hearing aids (HA group). All participants used the devices for at least 8 hours per day. Participants completed the Tinnitus Handicap Inventory (THI; Newman et al., 1996) at each of four appointments scheduled at three-month intervals over a year. Structured interviews were completed at each visit. During these interviews the following variables were examined: the effect of tinnitus on life, tinnitus loudness and tinnitus annoyance.

Analysis revealed that participants showed a marked reduction in scores over time, beginning at the first session three months after initiation of therapy and continuing progressively over subsequent measurements every three months up to the last visit at 12 months.  Results with ear-level sound generators and those with hearing aids were essentially identical. All three variables decreased by approximately 50% from the initial assessment to the final session at 12 months. The mean THI score decreased 52% from 57.9 to 27.9, the effect of tinnitus on life decreased 51% from 6.5 to 3.2, and tinnitus loudness ratings decreased from 7 to 3.6, a reduction of 48%. The common clinical criteria for significant improvement on the THI is 20 points (Newman et al., 1998) and 62% of the participants in the current study reached this goal by 6 months and 74% reached it by 12 months. Applying a criterion of 40% improvement to reflect a reduction in tinnitus disturbance—as proposed by P.J. Jastreboff—51% of the subjects achieved the goal by 6 months and 72% reached it by 12 months.

For all recorded variables, the time of treatment was always statistically significant, indicating that subjects were improving steadily over time. There was never a significant difference based on the type of device, indicating that sound generators and open-fit hearing aids were equally successful at alleviating tinnitus symptoms and reactions, at least for the subjects in this population, whose characteristics fell between categories 1 and 2 in Jastreboff & Hazell’s classification system.

Parazzini and colleagues evaluated tinnitus sufferers with mild high frequency hearing loss and measured their responses for up to 12 months. Though there was no evidence of plateaus in the data, it remains unknown whether improvements would continue if treatment were to continue beyond this point. Longer term studies would be valuable to determine at what point improvements plateau and if longer measurement periods yield differences between hearing aids and sound generator devices.

The instruments used in Parazzini’s study were either sound generators or hearing aids; none of the devices had both features. Many hearing aids available today offer tinnitus masking stimuli along with traditional amplification features. A similar paradigm examining hearing aids as well as combination devices could offer practical insight into tinnitus treatment options with currently available hearing instrument product lines. Because a goal of tinnitus retraining therapy is to restore auditory inputs to reduce awareness of the tinnitus, hearing aids could have particular benefits over sound generators, because they stimulate the auditory system with meaningful environmental sounds which may more effective at drawing attention away from the tinnitus, in addition to masking the tinnitus with the amplified sound.

Open-fit, behind-the-ear hearing aids appear to be a good solution for tinnitus patients: the ear canal remains open and unoccluded, thereby reducing the likelihood of increased tinnitus awareness. Another consideration is whether receiver-in-canal (RIC) instruments would be an even better choice. RICs are equally as effective as traditional open-fit hearing aids at minimizing occlusion and offer the opportunity to provide a broader high frequency range and more stable high frequency gain than is available when sound is routed thin or standard thickness tubing (Alworth, et al., 2010). This opportunity to provide an extended high-frequency amplification would be expected to increase auditory input in the frequency range where tinnitus is often perceived. Therefore, RICs may more effectively mask the tinnitus via amplification of environmental sounds, reducing tinnitus awareness and potentially, tinnitus annoyance and stress.

Parazzini’s study offers strong support for the use of open-fit hearing aids with tinnitus patients. Advances in hearing aid technology, such as feedback management, automatic signal processing, and the availability of tinnitus masking stimuli may make modern hearing aids even better suited for this purpose. As mentioned earlier, many opportunities exist for research in the treatment of tinnitus with hearing aids: effects of hearing aid style, sound therapy parameters, treatment and counseling strategies, and duration of treatment all remain white space for future researchers.

References

Alworth, L.N., Plyler, P.N., Bertges-Reber, M. & Johnstone, P.M. (2010). Microphone, performance and subjective measures with open canal hearing instruments. Journal of the American Academy of Audiology 21(4), 249-266.

Del Bo, L. & Ambrosetti, U. (2007). Hearing aids for the treatment of tinnitus. Progress in Brain Research 166, 341-345.

Henry J.A., Jastreboff M.M., Jastreboff P.J., Schechter M.A. & Fausti S.A.(2002).  Assessment of patients for treatment with tinnitus retraining therapy. Journal of the American Academy of Audiology, 13, 523 – 44.

Henry J.A., Jastreboff M.M., Jastreboff P.J., Schechter M.A. & Fausti S.A. (2003). Guide to conducting tinnitus retraining therapy initial and follow-up interviews. Journal of Rehabilitation Research and Development 40, 157 – 177.

Jastreboff, P.J. (1990). Phantom auditory perception (tinnitus): Mechanisms of generation and perception. Neuroscience Research 8, 221-254.

Jastreboff, P.J. & Hazell, J.W.P. (2004). Tinnitus Retraining Therapy: Implementing the Neurophysiological Model. Cambridge University Press.

Jastreboff P.J. & Jastreboff M.M. 2006. Tinnitus retraining therapy: A different view on tinnitus. Otorhinolaryngology and Related Specialties 68, 23 – 29.

Newman, C.W., Jacobson, G.P. & Spitzer, J.B. (1996). Development of the Tinnitus Handicap Inventory. Archives of Otolaryngology Head Neck Surgery 122, 143-148.

Newman, C.W., Sandridge, S.A. & Jacobson, G.P. (1998). Psychometric adequacy of the Tinnitus Handicap Inventory (THI) for evaluating treatment outcome. Journal of the American Academy of Audiology 9, 153-160.

Parazzini, M., Del Bo, L., Jastreboff, M., Tognola, G. & Ravazzani, P. (2011). Open ear hearing aids in tinnitus therapy: An efficacy comparison with sound generators. International Journal of Audiology, 50(8), 548-553.

Hearing Aids Alone can be Adjusted to Help with Tinnitus Relief

Shekhawat, G.S., Searchfield, G.D., Kobayashi, K. & Stinear, C. (2013). Prescription of hearing aid output for tinnitus relief. International Journal of Audiology 2013, early online: 1-9.

This editorial discusses the clinical implications of an independent research study and does not represent the opinions of the original authors.

The American Tinnitus Association (ATA) reports that approximately 50 million people in the United States experience some degree of tinnitus.About one third of tinnitus sufferers consider it severe enough to seek medical attention. Fortunately only a small proportion of tinnitus sufferers experience symptoms that are debilitating enough that they feel they cannot function normally. But even if it does not cause debilitating symptoms, for many tinnitus still causes a number of disruptive effects such as sleep interference, difficulty concentrating, anxiety, frustration and depression  (Tyler & Baker, 1983; Stouffer & Tyler, 1990; Axelsson, 1992; Meikle 1992; Dobie, 2004).

Therapeutic treatments for tinnitus include the use of tinnitus maskers, tinnitus retraining therapy, biofeedback and counseling . Though these methods provide relief for many the tendency for tinnitus to co-occur with sensorineural hearing loss (Hoffman & Reed, 2004) leads the majority of individuals to attempt management of tinnitus with the use of hearing aids alone (Henry, et al., 2005; Kochkin & Tyler, 2008; Shekhawat et al., 2013).  There are a number of benefits that hearing aids may offer for individuals with tinnitus:  audiological counseling during the fitting process may provide the individual with a better understanding of hearing loss and tinnitus (Searchfield et al., 2010); hearing aids may reduce the stress related to struggling to hear and understand; amplification of environmental sound may reduce perceived loudness of tinnitus (Tyler, 2008).

Prescriptive hearing aid fitting procedures are designed to improve audibility and assist hearing loss rather than address tinnitus concerns. Yet the majority of studies show that hearing aids alone can be useful for tinnitus management (Shekhawat et al., 2013). The Better Hearing Institute reports that approximately 28% of hearing aid users achieve moderate to substantial tinnitus relief with hearing aid use (Tyler, 2008). Approximately 66% of these individuals said their hearing aids offered tinnitus relief most or all the time and 29% reported that their hearing aids relieved their tinnitus all the time. However, little is known about how hearing aids should be adjusted to optimize this apparent relief from tinnitus. In a study comparing DSL I/O v4.0 and NAL-NL1, Wise (2003) found that low compression kneepoints in the DSL formula reduced tinnitus awareness for 80% of subjects, but these settings also made environmental sounds more annoying. Conversely, they had higher word recognition scores with NAL-NL1 but did not receive equal tinnitus reduction. The proposed explanation for this was the increased low-intensity, low-frequency gain of the DSL I/O formula versus the increased high frequency emphasis of NAL-NL1. Based on these findings, the author suggested the use of separate programs for regular use and for tinnitus relief.

Shekhawat and his colleagues began to address the issue of prescriptive hearing aid fitting for tinnitus by studying how output characteristics should be tailored to meet the needs of hearing aid users with tinnitus.  Specifically, they examined how modifying the high frequency characteristics of the DSL v5 (Scollie et al., 2005) prescription would affect subjects’ short term tinnitus perception.  Speech files with variable high frequency cut-offs and gain settings were designed and presented to subjects in matched pairs to arrive at the most favorable configuration for tinnitus relief.

Twenty-five participants mild to moderate high-frequency sensorineural hearing loss were recruited for participation. None of the participants had used hearing aids before but all indicated interest in trying hearing aids to alleviate their tinnitus.  All subjects had experienced chronic, bothersome tinnitus for at least two years and the average perception of tinnitus loudness was 62.6 on a scale from 1-100, where 1 is very faint and 100 is very loud. Subjects had a mean Tinnitus Functional Index (TFI; Meikle et al., 2012) score of 39.30. Six participants reported unilateral tinnitus localized to the left side, 15 had bilateral tinnitus and 4 reported tinnitus that localized to the center of the head, which is likely to be present bilaterally though not necessarily symmetrical.  The majority (40%) of the subjects reported their tinnitus quality as tonal, whereas 28% described it as noise, 20% as crickets and 12% as a combination of sound qualities. Tinnitus pitch matching was conducted using pairs of tones in which subjects were repeatedly asked to indicate which of the tones more closely matched the pitch of their tinnitus. The average matched tinnitus pitch was 7.892kHz with a range from 800Hz to 14.5kHz. When asked to describe the pitch of their tinnitus, most subjects defined it as “very high pitched”, some said “high pitched” and some said “medium pitched”.

There were 13 speech files, based on sentences spoken by a female talker, with variable high frequency characteristics. There were three cut-off frequencies (2, 4 and 6kHz) and four high frequency gain settings (+6, +3, -3 and -6dB). Stimuli were presented via a master hearing aid with settings programmed to match DSL I/O v5.0 prescriptive targets for each subject’s hearing loss.  Pairs of sentences were presented in a round robin tournament procedure  and subjects were asked to choose which one interfered most with their tinnitus and made it less audible. A computer program tabulated the number of “wins” for each sentence and collapsed the information across subjects to determine a “winner”, or the sentence that was most effective at reducing tinnitus audibility.  Real-ear measures were used to compare DSL v5 prescribed settings with the characteristics of the winning sentence and outputs were recorded from 250Hz to 6000Hz.

The most preferred output for interfering with tinnitus perception was a 6dB reduction at 2kHz, which was chosen by 26.47% of the participants.  A 6dB reduction at 4kHz was preferred by 14.74% of the subjects, followed by a 3dB reduction at 2kHz, which was preferred by 11.76%.  There were no significant differences between the preferences for any of these settings.

They found that when tinnitus pitch was lower than 4kHz, the preferred setting had lower output than DSL v5 across the frequency range. The difference was small (1-3dB) and became smaller as tinnitus pitch increased. When tinnitus pitch was between 4-8kHz, subjects preferred slightly less output than DSL v5 for high frequencies and slightly more output for low frequencies, though these differences were minimal as well. When tinnitus pitch was higher than 8kHz, participants preferred output that was slightly greater than DSL v5 at three frequencies: 750Hz, 1kHz and 6kHz. From these results a trend emerged: as tinnitus pitch increased, preferred output became lower than DSL v5 though the differences were not statistically significant.

Few studies investigating the use of hearing aids for tinnitus management have considered the perceived pitch of the tinnitus or the prescriptive method of the hearing aids (Shekhawat et al., 2013). The results of this study suggest that DSL v5 could be an effective prescriptive formula for hearing aids used in a tinnitus treatment plan, though the pitch of the individual’s tinnitus might affect the optimal output settings. In general, they found that the higher the tinnitus pitch, the more the preferred output matched with DSL I.O v5.0 targets. This study agrees with an earlier report by Wise (2003) in which subjects preferred DSL v5 over NAL-NL1 for interfering with and reducing tinnitus. It is unknown how NAL-NL2 targets would fare in a similar comparison, though the NAL-NL2 formula may provide more tinnitus relief than its predecessor because it tends to prescribe slightly higher gain for low frequencies and lower compression ratios which could potentially provide more of a masking effect from environmental sounds. The NAL-NL2 formula should be studied as it pertains to tinnitus management, perhaps along with consideration of other factors including degree of loss, gender and prior experience with hearing aids, since these affect the targets prescribed by the updated formula (Keidser & Dillon, 2006; Keidser et al., 2008). The subjects in the present study had similar degrees of loss and all lacked prior experience with amplification; the NAL-NL2 formula takes these factors into consideration, prescribing slightly different gain based on degree of loss or for those who have used hearing aids before.

The authors recommend offering separate hearing aid programs for use when the listener desires tinnitus relief. Most fitting formulae are designed to optimize speech intelligibility and audibility, and based on previous reports, an individual might prefer one formula when speech understanding and communication is their top priority, and may prefer another, used with or without an added noise masker, when their tinnitus is bothering them.

They also propose that tinnitus pitch matching should be considered when programming hearing aids, though there is often quite a bit of variability in results and testing needs to be repeated several times to increase reliability.  Still, their study agrees with prior work in suggesting that the pitch of the tinnitus affects how likely hearing aids are to reduce it and whether output adjustments can impact how effective the hearing aids are to this end. Schaette (2010) found that individuals with tinnitus pitch lower than 6kHz showed more reduction of tinnitus with hearing aid use than did subjects whose pitch was higher than 6kHz. This makes sense because of the typical bandwidth of hearing aids, in which most gain is delivered below this frequency range. Not surprisingly, another study reported that hearing aids were most effective at reducing tinnitus when the pitch of the tinnitus was within the frequency response range of the hearing aids (McNeil et al., 2012).  Though incorporating tinnitus pitch matching into a clinical protocol might seem daunting or time consuming, it is probably possible to use an informal bracketing procedure, similar to one used for MCLs, to get an idea of the individual’s tinnitus pitch range. Testing can be repeated at subsequent visits to eventually arrive at a more reliable estimate.  If pitch matching measures are not possible, clinicians can question the patient about their perceived tinnitus pitch range and, with reference the current study, adjust outputs in the 2kHz to 4kHz range to determine if the individual experiences improvement in tinnitus relief.

Proposed are a series of considerations for fitting hearing instruments on tinnitus sufferers and for employing dedicated tinnitus programs:

- noise reduction should be disabled;

- fixed activation of omnidirectional microphones introduce more environmental noise;

- in contrast to the previous recommendation, full-time activation of directional microphones will increase the hearing aid noise floor;

- lower compression knee points increase amplification for softer sounds;

- expansion should be turned off to increase amplification of low-level background sound;

- efforts should be made to  minimize occlusion, which can emphasize the perception of tinnitus;

- ensuring physical comfort of the devices can minimize the user’s general awareness of their ears and the hearing aids, potentially reducing their attention to the tinnitus as well (Sheldrake & Jastreboff, 2004; Searchfield, 2006);

- user controls are important as they allow access to alternate hearing aid programs and sound therapy options.

Dr. Shekhawat and his colleagues also underscore the importance of counseling tinnitus sufferers who choose hearing aids. Clinicians need to ensure that these patients have realistic expectations about the potential benefits of hearing aids and that they know the devices will not cure their tinnitus. Follow-up care is especially important to determine if adjustments or further training is necessary to improve the performance of the aids for all of their intended purposes.

Currently, little is known about how to optimize hearing aid settings for tinnitus relief and there are no prescriptive recommendations targeted specifically for tinnitus sufferers. Shekhawat and his colleagues propose that the DSL v5 formula may be an appropriate starting point for these individuals, as their basic program and/or in an alternate program designated for use when their tinnitus is particularly bothersome.  Most importantly, however, are the observations that intentional manipulation of parameters common to most hearing aid fittings may increase likelihood of tinnitus relief with hearing aid use. Further investigation into the optimization of these fitting parameters may reveal a prescriptive combination that audiologists can leverage to benefit individuals with hearing loss who also seek relief from the stress and annoyance of tinnitus.

 

References

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