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Addressing patient complaints when fine-tuning a hearing aid

Jenstad, L.M., Van Tasell, D.J. & Ewert, C. (2003). Hearing aid troubleshooting based on patient’s descriptions. Journal of the American Academy of Audiology 14 (7).

This editorial discusses the clinical implications of an independent research study. The original work was not associated with Starkey Laboratories and does not reflect the opinions of the authors.

As part of any clinically robust protocol, a hearing aid fitting will be objectively verified with real-ear measures and validated with a speech-in-noise test. Fine tuning and follow-up adjustments are an equally important part of the fitting process. This stage of the routine fitting process does not follow standardized procedures and is almost always directed by a patient’s complaints or descriptions of real-world experience with the hearing aids. This can be a challenging dynamic for the clinician. Patients may have difficulty putting their auditory experience into words and different people may describe similar sound quality issues in different ways.  Additionally, there may be several ways to address any given complaint and a given programming adjustment may not have the same effect on different hearing aids.

Hearing aid manufacturers often include a fine-tuning guide or automated fitting assistant within their software to help the clinician make appropriate adjustments for common patient complaints. There are limitations to the effectiveness of these fine tuning guides in that they are inherently specific to a limited range of products and the suggested adjustments are subject to the expertise and resources of that manufacturer.  The manner in which a sound quality complaint is described may differ between manufacturers and the recommended adjustments in response to the complaint may differ as well.

There have been a number of efforts to develop a single hearing aid troubleshooting guide that could be used across devices and manufacturers (Moore et. al., 1998; Gabrielsson et al., 1979, 1988, 1990; Lundberg et al., 1992; Ovegard et al., 1997). The first and perhaps most challenging step toward this goal has been to determine the most common descriptors that patients use for sound quality complaints. Moore (1998) and his colleagues developed a procedure in which responses on three ratings scales (e.g., “loud versus quiet”, “tinny versus boomy”) were used to make adjustments to gain and compression settings. However, their procedure did not allow for the bevy of descriptors that patients create; limiting potential utility for everyday clinical settings.  Gabrielsson colleagues, in a series of Swedish studies, developed a set of reliable terms to describe sound quality. These descriptors have since been translated and used in English language research (Bentler et al., 1993).

As hearing instruments become more complicated with numerous adjustable parameters, and given the wide range of experience and expertise of individuals fitting hearing instruments today, an independent fine tuning guide is an appealing concept. Lorienne Jenstad and her colleagues proposed an “expert system” for troubleshooting hearing aid complaints.  The authors explained that expert systems “emulate the decision making abilities of human experts” (Tharpe et al., 1993).  To develop the system, two primary questions were asked:

1) What terms do hearing impaired listeners use to describe their reactions to specific hearing aid fitting problems?

2) What is the expert consensus on how these patient complaints can be addressed by hearing aid adjustment?

There were two phases to the project. To address question one, the authors surveyed clinicians for their reports on how patients describe sound quality with regard to specific fitting problems. To address question two, the most frequently reported descriptors from the clinicians’ responses were submitted to a panel of experts to determine how they would address the complaints.

The authors sent surveys to 1934 American Academy of Audiology members and received 311 qualifying responses. The surveys listed 18 open-ended questions designed to elicit descriptive terms that patients would likely use for hearing aid fitting problems. For example, the question “If the fitting has too much low-frequency gain…” yielded responses such as “hollow”, “plugged” and “echo”.  The questions probed common problems related to gain, maximum output, compression, physical fit, distortion and feedback.  The survey responses yielded a list of the 40 most frequent descriptors of hearing aid fitting problems, ranked according to the number of occurrences.

The list of descriptors was used to develop a questionnaire to probe potential solutions for each problem.  Each descriptor was put in the context of, “How would you change the fitting if your patient reports that ___?”, and 23 possible fitting solutions were listed.  These questionnaires were completed by a panel of experts with a minimum of five years of clinical experience. Respondents could offer more than one solution to a problem and the solutions were weighted based on the order in which they were offered. There was strong agreement among experts, suggesting that their responses could be used reliably to provide troubleshooting solutions based on sound quality descriptions. The expert responses also agreed with the initial survey that was sent to the group of 1934 audiologists, supporting the validity of these response sets.

The expert responses resulted in a fine-tuning guide in the form of tables or simplified flow charts. The charts list individual descriptors with potential solutions listed below in the order in which they should be attempted.  For example, below the descriptor “My ear feels plugged”, the first solution is to “increase vent” and the second is to “decrease low frequency gain”. The idea is that the clinician would first try to increase the vent diameter and if that didn’t solve the problem, they would move on to the second option, decreasing low frequency gain. If an attempted solution creates another sound quality problem, the table can be utilized to address that problem in the same way.

The authors correctly point out that there are limitations to this tool and that proposed solutions will not necessarily have the same results with all hearing aids. For instance, depending on the compressor characteristics, raising a kneepoint might increase OR decrease the gain at input levels below the kneepoint. It is up to the clinician to be familiar with a given hearing aid and its adjustable parameters to arrive at the appropriate course of action.

Beyond manipulation of the hearing aid itself, the optimal solution for a particular patient complaint might not be the first recommendation in any tuning guide. For instance, for the fitting problem labeled “Hearing aid is whistling”, the fourth solution listed in the table is “check for cerumen”.  This solution appeared fourth in the ranking based on the frequency of responses from the experts on the panel. However, any competent clinician who encounters a patient with hearing aid feedback should check for cerumen first before considering programming modifications.

The expert system proposed by Jenstad and her colleagues represents a thoroughly examined, reliable step toward development of a universal troubleshooting guide for clinicians. Their paper was published in 2003, so some items should be updated to suit modern hearing aids. For example, current feedback management strategies result in fewer and less challenging feedback problems.  Solutions for feedback complaints might now include, “calibrate feedback management system” versus gain or vent adjustments. Similarly, most hearing aids now have solutions for listening in noise that extend beyond the simple inclusion of directional microphones, so “directional microphone” might not be an appropriately descriptive solution to address complaints about hearing in noise, as the patient is probably already using a directional microphone.

Overall, the expert system proposed by Jenstad and colleagues is a helpful clinical tool; especially if positioned as a guide to help patients find the appropriate terms to describe their perceptions. However, as the authors point out, it is not meant to replace prescriptive methods, measures of verification and validation, or the expertise of the audiologist. The responsibility is with the clinician to be informed about current technology and its implications for real world hearing aid performance and to communicate with their patients in enough detail to understand their patients’ comments and address them appropriately.

References

Bentler, R.A., Nieburh, D.P., Getta, J.P. & Anderson, C.V. ( 1993). Longitudinal study of hearing aid effectiveness II: subjective measures. Journal of Speech and Hearing Research 36, 820-831.

Jenstad, L.M., Van Tasell, D.J. & Ewert, C. (2003). Hearing aid troubleshooting based on patient’s descriptions. Journal of the American Academy of Audiology 14 (7).

Moore, B.C.J., Alcantara, J.I. & Glasberg, B.R. (1998). Development and evaluation of a procedure for fitting multi-channel compression hearing aids. British Journal of Audiology 32, 177-195.

Gabrielsson A. ( 1979). Dimension analyses of perceived sound quality of sound-reproducing systems. Scandinavian Journal of Psychology 20, 159-169.

Gabrielsson, A., Hagerman, B., Bech-Kristensen, T. & Lundberg, G. (1990). Perceived sound quality of reproductions with different frequency responses and sound levels. Journal of the Acoustical Society of America 88, 1359-1366.

Gabrielsson, A. Schenkman, B.N. & Hagerman, B. (1988). The effects of different frequency responses on sound quality judgments and speech intelligibility. Journal of Speech and Hearing Research 31, 166-177.

Lundberg, G., Ovegard, A., Hagerman, B., Gabrielsson, A. & Brandstom, U. (1992). Perceived sound quality in a hearing aid with vented and closed earmold equalized in frequency response. Scandinavian Audiology 21, 87-92.

Ovegard, A., Lundberg, G., Hagerman, B., Gabrielsson, A., Bengtsson, M. & Brandstrom, U. (1997). Sound quality judgments during acclimatization of hearing aids. Scandinavian Audiology 26, 43-51.

Schweitzer, C., Mortz, M. & Vaughan, N. (1999). Perhaps not by prescription – but by perception. High Performance Hearing Solutions 3, 58-62.

Tharpe, A.M., Biswas, G. & Hall, J.W. (1993). Development of an expert system for pediatric auditory brainstem response interpretation. Journal of the American Academy of Audiology 4, 163-171.