For some people, particularly those with more severe hearing losses, being suddenly cut off from the world of sound from a malfunctioning hearing aid can have serious consequences, ranging from the embarrassing to the life-threatening.

No one doubts the tremendous technical developments made with hearing aids in recent years. New digital signal processing techniques are capable of modifying the response of hearing aids in an immense number of ways. Computer-aided fitting techniques, combined with research-based amplification "targets," are ensuring that more and more people with hearing loss are receiving improved and personalized amplified signals through hearing aids. This is indeed good news for hearing aid wearers. Unfortunately, in the midst of this "high-tech" revolution, "low-tech" considerations may still intrude and often limit the potential benefit of hearing aids.

Effect of Humidity and Perspiration

One of these underestimated low-tech problems is the effect of humidity and perspiration upon hearing aid performance. To our knowledge, only two hearing aid manufacturers have even acknowledged this as a problem. They have successfully marketed a "water resistant" and even a "waterproof" hearing aid. Other "solutions" that are designed to address this problem appear to be woefully inadequate. Users of behind-the-ear (BTE) hearing aids can use a balloon-like thin rubber seal that fits over the hearing aid to protect the aid from moisture. This has not proved to be a popular measure, possibly because it is both inconvenient and apparently ineffective.

Hearing aids can also be stored overnight in desiccant containers that will dehumidify existing moisture. This is a recommended precautionary measure for hearing aid users to take. It will not help, however, when hearing aids malfunction while they are being worn.

Not a Trivial Problem

While it may sound like a trivial observation, we should keep in mind that hearing aids are being used by people because they are necessary. When a hearing aid malfunctions, the user is being deprived of the acoustical access to the world around him or her that the aid provides. For some people, particularly those with more severe hearing losses, being suddenly cut off from the world of sound can have serious consequences, ranging from the embarrassing to the life-threatening. It is not a trivial problem.

Study Conducted by SHHH

While we know that moisture-related problems do occur, we do not know how frequently they happen. It was in an attempt to answer this point that a questionnaire was distributed to members of Self Help for Hard of Hearing People at their 1999 SHHH Convention in New Orleans. Ninety-eight usable responses were completed.

Results

• 77 people (or 78 percent of the participants) reported that they had experienced moisture related problems with their hearing aids, while 21 respondents denied ever experiencing such problems.
• 15 of the people reported daily problems, 10 (10 percent) noted weekly problems, while the rest (54, or 55 percent) reported occasional problems with moisture.
• Of the 83 people wearing BTE hearing aids, 69 (83 percent) experienced problems while 14 (17 percent) did not.
• 15 of the respondents wore either an ITE or CIC hearing aid. Of these, eight (53 percent) reported problems while seven (47 percent) did not.

It should be noted that the type of hearing aids worn by the respondents do not reflect the percentage worn by the general population. These results show that a higher percentage of BTE hearing aid users experienced problems than did people wearing in-the-ear hearing aids; however, such problems commonly occurred with all types of hearing aids.

The respondents took a number of steps in an attempt to resolve the problem. These included:

• Blowing moisture out of the earmold tubing.
• Using a desiccant container.
• Waiting for the aid to dry out.
• Seeing their hearing aid dispenser.

Twenty-four of the subjects found it necessary to return to their hearing aid dispensers in an effort to resolve the problem. Six of the subjects found it necessary to send the hearing aid back to the manufacturer in order to resolve the problem.

Discussion

A foregone conclusion was that people experience moisture-related problems with their hearing aids. The authors of this article, both long-time hearing aid users, have personally had their hearing aids malfunction because of moisture, perspiration, or rain (sometimes, one cannot "get out of the rain!"). Further, the large number of anecdotal observations in this regard, by hearing aid wearers and hearing aid dispensers alike, provide convincing evidence of the existence of this problem. Even given the fact that those who responded to the questionnaire were those more likely to have experienced moisture-related problems than those who did not, the number and percentage of positive reports is very convincing. It is clear that hearing aids, even the most modern types, are susceptible to malfunction when worn in a humid or moisture-laden environment.

It should not be too much of a technical challenge for hearing aid manufacturers to develop waterproof or, at least, water resistant hearing aids. We can wear our watches in the shower or in the pool and expect them to work after the immersion. Other types of electronic devices are designed to be similarly immune to the effects of moisture. Many hearing aid wearers live in sections of the country in which high humidity is a daily occurrence. Others enjoy walking, exercise, golfing, boating, fishing (all reported by our subjects) during which activity they deserve the security of knowing that their hearing aids would continue to operate correctly. They do not have this security now.

We strongly recommend that hearing aid manufacturers, as they develop more "high-tech" technical solutions to improve hearing function among hearing aid users, not ignore such equally vital challenges as ensuring immunity of hearing aids to moisture-related problems.

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Acknowledgements:
This article was supported in part by grant #RH133E30015 from the U.S. Department of Education, NIDRR, to the Lexington Center. The assistance of Julie Eum in analyzing the data is gratefully acknowledged.
Mark Ross, Ph.D., is an SHHH member from Storrs, Connecticut, and writes the column "Developments in Research and Technology" in each issue of Hearing Loss.
Francis Beecher is an SHHH member from Madison, Wisconsin. In addition to being a long-time hearing aid wearer, he formerly dispensed hearing aids.