Music and the PCAST Recommendations -Part 4

So…. when is a hearing aid prescription a hearing aid prescription?

Hearing aid prescription is a regulated act in many jurisdictions around the world. Regulation is not an issue unto itself- the important issue is why did local jurisdictions want hearing aid prescriptions to be regulated in the first place.  Yes, regulations can change, but the reasons behind them generally do not.

This final blog entry of this four part series may sound like a bit of a “downer” but it is not intended to be that way.  Changes are coming down the pipeline and there are some issues that need to be addressed, including hearing aid verification to ensure safety and an optimal setting, whether for speech or for music.  I address some questions here but not a lot of answers, but I have no doubt that they will come.

If the PCAST recommendations are accepted (see parts 1, 2 and 3 of this blog series) the definition of a hearing aid recommendation (and indeed a hearing aid) will be altered. Regulations will need to be rewritten but then again, perhaps not.  State jurisdictions are more powerful than federal ones (at least in the United States).  While this is not true of other countries, the principle of uniformity with local and federal regulation make sense and this is because both are based on the same sets of data and agreed upon facts.


But what would happen if “basic” hearing aids were removed from the purview of the audiologist and sold “over the counter” as they currently are in some countries around the world. Does this really improve access? Are hearing aids more accessible in Japan where some models of retail include “over the counter” sales?

Currently, a hearing aid prescription involves the assessment, the specification of a number of electro-acoustic parameters, the counselling and information provision, the recommendation of assistive listening devices, and perhaps, almost as importantly, the verification of what we think we are prescribing actually is what the client is receiving.

This overview of a hearing aid prescription has nothing to do with whether a hearing aid is fit for a mild, moderate, or even profound hearing loss. The concept of the PCAST membership defining a “basic” hearing aid is erroneous.

If a hearing aid only provides 25 dB- 30 dB of gain, making it suitable for someone with a mild to moderate sensory/neural hearing loss (and unsuitable for someone with a mild to moderate conductive hearing loss (see part 2)), why does the hearing aid function not need to be verified? Does a person with a mild to moderate hearing loss not need any counselling, communication strategies, or assistive listening devices.  And magically, do these people not need to have their “basic” hearing aids verified to ensure that the gain and output are appropriate, and not potentially deleterious to their long term hearing status?

PSAPs and hearing aids:

To a certain extent, we already have this problem. I have seen and assessed PSAPs that have the identical gain, output, frequency response, and WDRC that other hearings have.  One is “intended for the hard of hearing consumer” and the other is “not intended for the hard of hearing consumer”; both are identical devices but one requires a hearing aid prescription with everything that that entails including follow-up and record keeping, and the other (the PSAP) requires none of this.  A hearing aid then seems to be defined according to how a manufacturer decides to market the device.  Indeed, they may market the identical device as both a PSAP and as a hearing aid, and get the benefits of both sides of the marketplace- yet this is the same device (perhaps with a different shell configuration or style). This is already occurring in the marketplace.


And couple this with the impending control over a hearing aid using either internet based, or Smart phone controlled applications. Conceivably the hearing aid that was prescribed, optimized, and verified by the audiologist, could be reprogrammed at home by the end consumer with any number of devices and tools.  Also, questions such as “who do you call for support if your PSAP needs service?” need to be addressed.

Taken together, the audiologist really will have no control over what constitutes a hearing aid prescription.

It may be that the only thing that any regulator (whomsoever that may be) controls is the maximum output (or OSPL90). If this is indeed controlled, then the worst case scenario would be that the hard of hearing person returns to our offices with their tails dragging behind them requesting that their hearing aids be returned to the previous state.

We do live in interesting times!



About Marshall Chasin

Marshall Chasin, AuD, is a clinical and research audiologist who has a special interest in the prevention of hearing loss for musicians, as well as the treatment of those who have hearing loss. I have other special interests such as clarinet and karate, but those may come out in the blog over time.


  1. I am not sure that this really is a difference in hearing aid formulae. Ultimately a hard of hearing person may need X dB of gain at a certain frequency, and not X/2 or 2X. This specification is what the formulae are designed to achieve. Differences may be in how much gain is provided in excess of 6000 Hz (if any) or on the other end of the scale, how much gain is prescribed for the left hand side of the piano keyboard. In many hearing aid fittings, there is a vent, or non-occluded pathway, and these very low frequency sounds would enter backwards through the vent in any event, regardless of how much low frequency gain was prescribed.

  2. And this will bring out the differences between long held hearing aid prescription formulas, and audio engineering principles of EQing and compression. And the main difference is the number and placement of the EQ bands. IOW, sound quality and fidelity for dollars spent..

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