Starkey Research & Clinical Blog

The Speech, Spatial and Qualities of Hearing Scale (SSQ): A Gatehouse Legacy

Gatehouse, S. & Noble, W. (2004). The speech, spatial and qualities of hearing scale (SSQ). International Journal of Audiology, 43, 85-99.

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

Self-assessment scales provide insight into everyday experiences and perceptions of hearing impaired individuals making them valuable companions to laboratory research and helpful tools for clinicians.  A variety of self-assessment indices are available for use with aided or unaided individuals and target a variety of issues including hearing aid usage patterns, binaural or monaural preference, volume and program preferences, ability to understand speech in quiet and noise, and ability to function in social situations.  Gatehouse and Noble point out that most laboratory research and self-assessment scales view speech perception as the primary issue related to hearing handicap, with improved audibility and suppression of competing noise being the primary goal of auditory rehabilitation. But in everyday life, understanding speech may constitute only part of a hearing-impaired individual’s perceived difficulties.  For instance, it is important to locate and identify audible events in order to be fully aware of the environment and safely navigate a variety of surroundings. With the development of the SSQ, Gatehouse and Noble hoped to provide a more comprehensive measure of hearing disability, taking into account the perception of both spatial relationships and sound quality. Furthermore, they investigated the relationship between disabilities in these areas to perceived hearing handicap.

Research regarding auditory scene analysis by Bregman (1990) indicates that a listener in a group situation must first parse the complex acoustic environment into sound sources or “streams” so that they can be attended to and monitored individually. In other words, in a noisy situation, a listener must be able to group together the acoustic elements that make up one particular voice before processing the content of the message. Although it would be easier if it did, conversation rarely proceeds in an orderly fashion with one participant speaking at a time. Rather, in groups, one participant might initiate a response while the previous person is still speaking, or two individuals might speak at the same time. This requires a listener to not only attend to specific speech streams, but to monitor other speech sources in order to be ready to switch attention when necessary.  Accomplishing this task involves binaural hearing, localization, attention, cognition, and vision, and successful communication in groups can be affected by all of these variables. Because the SSQ investigates auditory perceptions of movement, location, and distance as well as sound quality perceptions, such as mood and voice identification in addition to issues related to speech communication, it may more realistically address how hearing loss affects an individual’s everyday life.

The goal of Gatehouse and Noble’s study was twofold: to use the SSQ to examine what is disabling about hearing impairment and to determine how those disabilities affect hearing handicap. There were 153 participants in the study: 80 females and 73 males, with an average age of 71 years. The better-ear average (BEA) for octave frequencies from 500 to 4000Hz was 38.8dB.  The worse-ear average (WEA) was 52.7dB. In addition to the SSQ, subjects completed a 12-question hearing handicap scale developed in part from the Hearing Disabilities and Handicaps Scale (Hetu et al., 1994) and from an unpublished general health scale (Glasgow Health Status Inventory). The items were scored using a 5-point scale, yielding a global handicap score. A higher score indicated greater handicap. Negative scores on the SSQ indicate greater disability, so negative correlations between the SSQ and handicap scores were expected.

The SSQ was designed to be administered as an interview rather than as a self-administered scale. The interview format ensures that the subject understands the questions and can request clarification when necessary. The scale is divided into three domains: 14 items on speech hearing, 17 items on spatial hearing, and 18 items on “other” functions and qualities of hearing. The “other” qualities section contains items related to recognition and segregation of sounds, clarity, naturalness, and listening effort.  Items are scored with ratings of 1 to 10, with the most positive response always represented with a higher number, on the right side of the response sheet. For example, the left side of the scale represents a complete absence of a quality, complete inability to perform a task, or complete effort required. The right side of the scale indicates complete presence of a quality, complete ability, or complete absence of effort.  The left to right, negative-to-positive scoring of items was consistently maintained throughout the scale in an effort to minimize confusion.

They found that degree of hearing impairment correlated well with disability as measured by the SSQ and that the SSQ scores in turn correlated well with handicap, but that impairment itself did not correlate well with handicap. This result was expected and was in agreement with previous research. Asymmetry of hearing loss was not correlated significantly with items in the speech-hearing domain, but did correlate strongly with spatial-hearing and “other” quality domain items such as ease of listening, clarity, and sound segregation.

Examination of SSQ scores within the speech hearing domain showed that the highest ratings were given for one-to-one conversation in quiet. The lowest ratings were for group conversations and contexts in which attention must be divided among two or more sound sources simultaneously.  In the spatial hearing domain, respondents generally rated their directional hearing ability higher than the ability to judge distance or movement. For the “other” qualities domain, items related to naturalness of one’s own voice, recognition of the mood of others from their voices, and recognition of music had the highest scores and those related to ease of listening had the lowest scores.

Following examination of the SSQ scores themselves, the individual items within each of the three SSQ domains were ranked according to the strength of their correlation with hearing handicap. Within the speech-hearing domain, hearing handicap was most influenced by disability in contexts requiring divided or rapidly shifting attention: conversation in a group of people, following two conversations at once, and missing the start of what the next speaker says.  However, handicap was also influenced by difficulty talking to one person in quiet conditions. It is not surprising that a person who perceives difficulty understanding speech in relatively favorable conditions would experience greater concern about their overall communication ability.  Difficulty understanding conversation in noisy situations can be externalized or blamed on the environmental conditions, whereas difficulty in quiet is likely to be internalized and attributed to one’s own disability.

Interestingly, many items in the spatial-hearing domain were as highly correlated with handicap as those within the speech-hearing domain. Questions related to determining the distance and paths of movement, the distance of vehicles, the direction of a barking dog, and locating a speaker in a group setting all contributed to perceived handicap. This underscores the importance of spatial hearing for environmental awareness as well as successful participation in conversation and suggests that examination of spatial hearing may help clinicians and researchers better understand an individual’s experience with their hearing loss.

Several of the items in the “other” qualities section of the SSQ were strongly correlated with handicap. The ability to identify a speaker, to judge a speaker’s mood, the clarity and naturalness of sound, and the effort needed to engage in conversation were among the items most strongly related to hearing handicap.  The authors explain that these abilities affect an individual’s sense of social competence. Failure to accurately interpret the identity or mood of a speaker or the need for increased effort to participate in conversation may have an isolating effect, causing an individual to avoid social situations or even telephone conversations because they fear they will be unable to participate fully or successfully.

Not surprisingly, Gatehouse and Noble found that hearing thresholds were related to SSQ disability scores and SSQ scores were related to handicap, but impairment itself was not strongly correlated to handicap. This finding was expected and is in agreement with previous reports (Hetu et al., 1994). The relationship between impairment, disability, and handicap is important and is familiar to audiologists, in that we routinely discuss how a patient’s hearing loss affects his or her activities and everyday lifestyle. Though consideration of the audiogram is of course important, the way hearing loss interacts with work-related and social activities – things a person must do or enjoys doing  - more likely determines their perceived handicap and therefore their motivation to pursue auditory rehabilitation.

The finding that spatial hearing disability was strongly correlated with handicap may have implications for asymmetric hearing loss as well as the fitting of bilateral hearing aids. Individuals with asymmetric hearing thresholds will have more difficulty localizing sound and therefore may experience more of a handicap related to the discrimination of auditory spatial relationships and movement.  For instance, an individual with asymmetric hearing loss might hear conversation easily but might experience stress because they are unable to judge the location or approach of a car that is not visible. Because individuals with a better or normal ear might rate their speech discrimination performance relatively well in quiet and even moderately noisy places, an assessment scale that examines only speech-related hearing disability might underestimate their perceived hearing handicap. Consideration of spatial hearing deficits might therefore provide a more realistic and helpful assessment of an individual’s functional difficulties. Perception of auditory spatial relationships is likely to be improved with the use of bilateral hearing aids for individuals with binaural hearing loss, so the correlation between spatial hearing items on the SSQ to hearing handicap may also be viewed as further support for the recommendation of two hearing aids.

The correlations across the three domains of the SSQ to the scores on the handicap scale indicate that the SSQ is effectively addressing several variables that contribute to perceived hearing handicap. The impact of speech recognition and discrimination on perceived handicap is well established. The impact of other skills such as determining distance, movement, voice quality, and mood is less well understood but may be an equally important component in understanding an individual’s feelings of social competence and confidence as well as their sense of safety and orientation in a variety of environments. The SSQ provides clinicians and researchers with an additional tool to more fully understand the impact of hearing loss on everyday lives.

References

Bregman, A. (1990). Auditory Scene Analysis: The Perceptual Organization of Sound. Cambridge, MA: MIT Press.

Gatehouse, S. & Noble, W. (2004). The speech, spatial and qualities of hearing scale (SSQ). International Journal of Audiology 43, 85-99.

Hetu, R., Getty, L., Phlibert, L., Desilets, F., Noble, W. (1994). Development of a clinical tool for the measurement of the severity of hearing disabilities and handicaps. Journal of Speech-Language Pathology and Audiology 18, 83-95.