Premium Digital Hearing Aids - Part One

By Mark Ross

Editor: You can count on Dr. Mark Ross to call it like he sees it, and that's what he does in this article. He points out that the top-of-the-line hearing aids may not help you hear any better than the entry level aids, and that what you're paying for with more expensive aids is more bells and whistles!

This article originally appeared in the March/April issue of Hearing Loss magazine and is reprinted with Dr. Ross' kind permission.

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A "premium" or "top of the line" hearing aid is one that incorporates the most technologically advanced and potentially useful features currently available. One recent trade journal article defines the difference between a premium hearing aid and other models as the inclusion of automatic and innovative features. The more of these that are included in a given aid, the greater the likelihood that it would be considered a premium or top of the line model. Clearly, the designation also carries with it the implicit, if not explicit, promise that the overall benefits that one achieves with a premium hearing aid are going to exceed those obtainable with a more economical hearing aid. But we should keep in mind that it is also a hearing aid that invariably comes with a price tag commensurate with the elite label.

According to the article, the determining consideration in moving from an entry level (less expensive) hearing aid to a premium (more expensive) model is the user's life style, that is, whether he or she leads a busy, active life in many different listening environments, or whether social time is spent in quiet, less demanding listening environments. We should note that the ability to actually hear better with these aids is not mentioned in the article. Convenience is stressed and not hearing. The reason for this, I suspect, is that there is little or no clinical evidence that directly compares the hearing performance of premium aids with other hearing aids.

The final factor in recommending a premium hearing aid for a particular person is, again according to the above-mentioned article, based on budgetary constraints. No matter what a person's life-style, a premium hearing aid should be recommended only for those who can afford to pay the "premium" price. Thus, the intention is to try to meet a person's listening needs within the very real limits of affordability. A premium hearing aid, therefore, would be reserved for those who have an active life, are socially active, and can afford to pay a "premium" price for the added convenience of the special features.

In our society, we are conditioned to believe that "you get what you pay for." We are accustomed to quality differences being reflected in the cost of an object or service. The notion that this also applies to hearing aids does not seem strange to us. If someone has listening needs that require the inclusion of the latest automatic and innovative features, and can afford the premium cost, why shouldn't this person purchase what he or she desires (and presumably needs)? While one can, perhaps, make a social policy argument against this notion, a more telling reason is that the presumed listening benefits of a premium hearing aid have little or no support in the hearing aid literature. In other words, the idea that people are getting extra hearing benefit commensurate with the additional cost is debatable. Evidently many people who purchase premium hearing aids feel the same way, since industry figures show that fully 26% of such aids are returned for credit.

In recent years, the sheer number of new features introduced in digital hearing aids has been enormous. The various hearing aid companies are in a constant and intense competitive race to introduce new ones in order to differentiate themselves from their competitors. Different hearing aid models, incorporating what is presented as some "revolutionary" new development, seems to be introduced every year or so. Capturing or maintaining market share - the economic imperative - is clearly the driving force. In the ideal world, no new hearing aid feature would be introduced until and unless its presumed listening benefits were evaluated and substantiated with human beings. But from what I can see, this does not happen very often. Instead of evidence of the clinical benefit of some newly introduced feature, what we get is promotional material presented as self-evidently positive. (I mean, who can argue with hearing aids that employ "artificial intelligence," nano-technology, or include a 128-channel adaptive noise reduction circuit?) It is difficult for anyone, consumer or professional, not to be impressed when reading this material - I know that I am. It all sounds so logical - but we do have to keep in mind that a marketing description, no matter how appealing or self-evidently obvious, is not equivalent to a well-controlled clinical (not laboratory) research study.

As a consequence of the rapid introduction of new hearing aid models, it seems that the features highlighted in a previous generation of premium hearing aids are now being included in this year's "entry level" or "affordable" models. The features haven't changed; the presumed advantages of last year's model are still as relevant (or irrelevant) as ever. . We can get some idea of what constituted a previous generation's "premium" hearing aid by looking at a table in the article cited above in which the characteristics of 25 "affordable" hearing aids are briefly described. Some of the more common features included with these currently- labeled affordable hearing aids are:

* Wide Dynamic Range Compression (WDRC). This feature automatically varies the amount of amplification applied to an input sound signal. Soft sounds may be amplified somewhat more then louder sounds, with the intention of making them audible, but still soft. Loud input sounds will receive less amplification, but should still sound loud, although not uncomfortably or unpleasantly so. The goal is to "package" the range of input sounds into a person's usable residual hearing range, i.e., the area between the impaired thresholds (e.g. 60 dB) and the point where sound becomes unpleasantly loud (let's assume, 95 dB). Ideally, there would also be a volume control that permits the user to override, at least to a certain extent, the WDRC circuit (to allow for situational and personal preferences).

* Adaptive Feedback Management. A number of hearing aids on this list include an effective feedback control circuit, one that uses a technique that does not modify the frequency response of the hearing aid. When an acoustic squeal occurs, the hearing aid automatically identifies the offending frequency and creates an internal cancellation signal. An effective feedback management system will permit a user to increase the gain of a hearing aid by 10 or 15 dB without feedback occurring. Open ear fitting would not be possible without this development.

* Channels and Bands (sometimes these terms are used interchangeably). The term "channel" usually refers to the ability to modify compression characteristics, while "band" refers to the ability to change the degree of amplification of the band (separate from the other bands). The hearing aids listed in this table display a considerable range of offerings in terms of the number of channels and bands offered. We should note that there is little clinical evidence for the presumed benefits of more than two channels and three or four equalization bands.