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Johnson, Earl E. AuD, PhD

The Hearing Journal:  January 2018 – Volume 71 – Issue 1 – p 34

There has been a recent push for more electronic sound amplifiers to provide affordable and accessible options that meet the needs of a large swath of people with hearing loss, particularly aging adults. These devices are available as over-the-counter (OTC) wearable hearing devices or personal sound amplification products (PSAPs; e.g., FDA 2009; PCAST, 2015). The 2016 recommendations from the National Academies of Sciences, Engineering, and Medicine included the need for defining safe output sound pressure level (SPL) for sound amplifiers as determined in conjunction with national experts in hearing conservation (NASEM, 2016). Presumably then, the concern for amplitude levels in the ear of a hearing-aid wearer is really the same type of concern that is often expressed for workers exposed to occupational noise hazards: that of too much amplitude level over a period (e.g., ISO 1999, 2013; OSHA 29 CFR 1910.95; NIOSH, 1998).

hearing aids, audiology

In this spirit, a study was published on the expected safe output levels of sound amplification devices (Int J Audiol. 2017;56[11]:829). The topic of the study is an old and somewhat controversial one (e.g., Brit J Audiol. 1971;5:99). There is current interest, however, in the availability of OTC hearing aids for individuals with up to a self-perceived mild to moderate hearing loss. In the 2017 study, safe output levels were reported to increase as hearing loss worsens. For an individual with normal hearing sensitivity at 0 dB HL, the safe output SPL was determined by calculation as 90 dB SPL. For an individual with no more than a mild loss (i.e., 40 dB HL), the safe output was 105 dB SPL. For an individual with no more than a moderate loss (i.e., 55 dB HL), the safe output was 111 dB SPL (Int J Audiol. 2017).

Hearing aids as medical devices with prescribed amplification settings often achieve better outcomes than non-prescriptive fittings such as OTC wearable hearing devices and PSAPs (e.g., Hear Rev, 2010). The better outcomes are a byproduct of maximizing utility (e.g., ensuring speech recognition performance and controlling loudness across listening environments) and involving the wearer in a personalized rehabilitation plan to meet their specific needs (e.g., J Am Acad Audiol. 2012;23[10]:768). Concomitantly, there are only a few advantages of an advanced hearing aid over a basic hearing aid of medical device quality when both types of devices have been fit using prescribed settings (Gerontology. 2014;60[6]:557).

The cost and accessibility of hearing aids fit to prescriptive recommendations, however, has been less than desired by some entities. Alternative devices like OTC hearing aids and PSAPs, which are both non-prescriptive, have emerged to fill the void of unmet need of people with hearing loss who don’t use amplification. The void, however, may not be as large as anticipated when data from countries where prescribed hearing aids are freely offered through socialized health care systems are considered. That is, the use/adoption/ownership rate of no cost (to the patient) medical device quality hearing aids is not more than 40 percent (IOM-NRC, 2014).

Instead of asking the far more philosophical question:

“If a tree falls in a forest and no one is around to hear it, does it make a sound?”, a rather practical thought experiment question to ask is: “If a hearing aid—even an OTC hearing aid—is in someone else’s ear, should we care how much sound it makes?”

I believe so. An aid will make sound because a person is expected to be present and hear it. Like other professionals in the medical field, licensed hearing health care professionals want to do no net harm. Hearing health care professionals care about safe output levels. Corporate and social responsibility ethics suggest a similar concern from manufacturers of hearing aids and other electronic sound amplification devices. By adhering to the safe output SPL, regardless of the device and delivery system in place, all sound amplification devices can be worn safely to protect against further hearing loss induced by the devices themselves.

*General Disclaimer: The contents of this article do not necessarily represent the official position of the U.S. Department of Veterans Affairs or the U.S. government. Dr. Johnson has a part-time audiology practice, Johnson Hearing Technology and Communication, PLLC.

Author: Earl E. Johnson, AuD, PhD