In the classic movie, “The Wizard of Oz,” Dorothy realizes in order to reach the Emerald City, she must first travel through the dark and unfamiliar Enchanted Forest. Worried that they will be attacked, the Tinman predicts the forest will be filled mostly with “lions and tigers and bears.”  

In recent years, audiology has faced threats due to a variety of factors—some of our own making—that have some fearful of the future. In the United States, an estimated 30 million individuals have measurable hearing loss, yet according to MarkeTrak IX (2015), only 30.2 percent of those with hearing loss own hearing aids. In recent years, numerous federal agencies have focused their attention on increasing hearing aid use, primarily though improving accessibility and affordability. 

Beginning in 2009, the Food and Drug Administration (FDA) introduced a guidance document for personal sound amplification products (PSAPs). To avoid classification as a medical device, PSAPs cannot be marketed in the United States as products intended for individuals with hearing loss or to compensate for hearing loss (FDA 2009, 2013). 

Some of these products have technical and performance characteristics that are quite similar to the Class I and Class II hearing aids that the FDA regulates. The determination of whether a product is a “device” that the FDA may regulate is based on the Federal Food, Drug, and Cosmetic Act (FDCA) definition of a device as one “intended for use in diagnosis of disease or other conditions, or in the cure, mitigation, treatment or prevention of disease” (FDCA, 1938). The FDA does not regulate PSAPs as medical devices, although they may regulate them under the electronic provisions of the FDCA. Furthermore, the Consumer Product Safety Commission has the authority to examine safety concerns regarding PSAPs.

Concerns regarding the safety and efficacy of PSAPs led to a series of hearings on whether to create a new category of “over-the-counter” (OTC) hearing aids designed for those with hearing loss that would be regulated by FDA. After a process spanning several years, President Donald Trump signed into law the Food and Drug Administration’s (FDA) Reauthorization Act of 2017 on August 18, 2017. The legislation included the Over-the-Counter Hearing Aid Act designed to provide greater accessibility and affordability to hearing aids for those individuals with hearing loss. 

The OTC Hearing Aid Act is designed to allow adults, aged 18 or older, with perceived mild-to-moderate hearing loss to access a new category of OTC hearing aids without the requirement to see a physician or audiologist. The new law, which was introduced last March by Sens. Elizabeth Warren (D-MA) and Chuck Grassley (R-IA), was passed by the U.S. House of Representatives and U.S. Senate on July 12 and August 3, 2017, respectively.

The new law requires the FDA to create and regulate a class of OTC hearing aids to ensure that they do not sacrifice safety in the name of improved accessibility and affordability. The law mandates the FDA to establish an OTC category for adults with “perceived” mild-to-moderate hearing loss within three years of passage of the legislation and finalize a rule within 180 days after the close of the comment period. In essence, this provides an approximate deadline of March 2021 for the final ruling to go into effect. To that end, although we do not yet know what the final ruling will look like, there are already several trends emerging. 

FIGURE 1. Real-ear measurements for Apple Airpod headphones measured for streamed music
FIGURE 1. Real-ear measurements for Apple Airpod headphones measured for streamed music (“All I Do Is Win,” by DJ Khalid) on an iPhone X at ¼ (green), ½ (purple), and full-on (teal) volume.

Comparable Technology

First, PSAPs cannot be simply dismissed as “cheap” hearing devices anymore. The frequency response, gain, and output parallels many low-power hearing aids in current use. FIGURE 1 illustrates the real-ear aided response (REAR) for the Apple Air Pods measured for music (“All I Do Is Win,” by DJ Khalid) streamed from an iPhone X at ¼, ½, and full-on volume, indicating a maximum power output (MPO) of approximately 105 dB SPL. 

Many devices use compression amplification, multichannel signal processing, and wireless functionality. Some use directional microphones, noise reduction, and feedback cancellation. Although the FDA makes the distinction on intended use, signaled through advertising and labeling, both PSAPs and hearing aid types of devices may be physically and electronically the same. 

Because PSAPs do not require a medical prescription or professional fitting, they often are described as the audio equivalent of reading glasses. Of note, however, is that even reading glasses are regulated under the FDA. Sunglasses, spectacle frames, spectacle lens, and magnifying spectacles are medical devices exempt from the Premarket Notification 510(k) submission to the Food and Drug Administration (FDA). Although these devices are 510(k) exempt, several other FDA regulations apply, specifically as they pertain to good manufacturing practice through quality systems (QS) requirements set forth in 21 CFR 820 and safety, requiring spectacles and/or sunglasses to be impact resistant under 21 CFR Part 801.410. It is difficult to imagine the FDA failing to ensure that users who seek to purchase OTC hearing aids are similarly protected in the future. 

A recent article examined electroacoustic results and simulated real-ear measurements from representative PSAPs compared to Class II regulated hearing aids (Reed et al, 2017a). The four primary electroacoustic measures for comparison were frequency response, equivalent input noise, total harmonic distortion, and maximum output (MPO) sound pressure level, which relate to sound quality and prevention from overamplification. Results indicated that one-half of the devices met all four electroacoustic tolerances evaluated in the study, with the remaining devices meeting tolerance on three or less of the electroacoustic measures. 

FIGURE 2. In-the-ear hearable styles currently in use
FIGURE 2. In-the-ear hearable styles currently in use (i.e., Bragi, NuHeara, Waverly Labs, Jabra).

In addition, simulated real-ear measurements indicated that nine of the PSAP devices were able to be adjusted to approximate National Acoustic Laboratories’ (NAL) prescriptive gain targets within 10 dB, while only three were able to match NAL targets within 5 dB. In terms of conformity to important electroacoustic measures, it is clearly not the case of whether PSAPs can provide comparable performance, but ensuring whether consumers can trust that the specific device they purchase will perform as advertised without FDA oversight. 

With regards to consumer benefits, another study (Reed et al, 2017b) investigated whether PSAPs and traditional hearing aids were associated with comparable improvements in speech understanding in noise for persons with mild-to-moderate sensorineural hearing loss. In this case, all participants were fitted professionally with each device, and three of five provided comparable speech understanding in noise to a traditional hearing aid that cost significantly more. One PSAP provided negligible benefit, and one degraded speech understanding relative to unaided performance. As noted, however, this study likely provided the “best-case” scenario for PSAPs, in that hearing health-care professionals fitted all devices. It is difficult to ascertain whether similar results would have been found if these devices had been self-fit, similar to the way that PSAPs (and eventually OTCs) would be adjusted in real life. 

Ironically, the PSAP device that performed the poorest in the Reed et al (2017b) study was the MSA 30X, manufactured by Florida-based Global Concepts Limited, Inc. Advertisements for the MSA 30X claimed that the product allows users to “hear people clearly in crowded restaurants without missing a word,” which raised the attention of the Federal Trade Commission (FTC). Over the course of its investigation, the FTC found the defendants had no proof to back up their claims. 

In May 2018, the FTC announced that Global Concepts Limited, Inc. agreed to settle a complaint alleging it made false or unsubstantiated claims that MSA 30X allows people who have trouble hearing to hear clearly, and falsely represented that independent studies prove the MSA 30X helps people hear up to 30 times better.

In summary, the technology associated with today’s PSAPs, many of which will become tomorrow’s OTC devices, provide heterogeneous electroacoustic performance and user benefits across devices. While some comprise comparable features and benefits to traditional hearing aids when fitted professionally by an audiologist, it remains to be seen whether these findings will hold up when they are subject to self-fitting through OTC. Furthermore, it remains to be seen whether the PSAP category becomes superfluous after the FDA makes its final ruling for OTC devices. 

FIGURE 3. Hybrid “wired/wireless” hearable style
FIGURE 3. Hybrid “wired/wireless” hearable style (i.e., JBL).

Disruptive Innovations

Although some professionals have spoken disparagingly about the emergence of PSAPs and OTC devices and the potential for “commoditization” of hearing aid technology, it also has challenged manufacturers to think differently from past solutions. For example, although rechargeable hearing aid batteries have been around for decades, PSAPs, OTCs, and especially the new “hearable” category have moved them into the mainstream, especially for Li-Ion, NiMH, and Silver-Zinc battery designs.

The portmanteau “hearable” is a combination of the terms wearable and hearing aid, as hearables combine major features of wearable technology with the traditional definition of audio-based connectivity for music, speech and telephone. The emergence of the baby boomer generation as a primary target for the hearing aid market has found that, while boomers are less stigmatized by hearing loss and hearing aids, they in turn have higher expectations for hearing aid performance. Consumer electronics companies and traditional hearing aid manufacturers alike have recognized that the new generation of hearing aid users want devices that are more than traditional “stand-alone” products that amplify gain as a function of frequency (Fabry and Groth, 2017); “Made-for-iPhone” and “Made for Android” processing provide “connected” technology through a direct Bluetooth link between phone and hearing aids. The next revolution, sparked by “hearable” devices, transition hearing aids to “multipurpose” devices that combine audio processing with embedded sensors to track steps, heart rate, pulse oximetry, body temperature, motion, and even electro-encephalogram (EEG) signals. The applications for this technology include tracking sleep, stress, activity, attention, and falls, and are blurring the distinction between “hearing aids” and “hearing health devices.” 

While hearables and hearing aids are converging, some important differences remain between the two technologies. First, while the stigma of hearing aids is decreasing, many of the consumer electronics companies are focused on “in-the-ear” form factors (FIGURE 2) rather than the “behind-the-ear” and “receiver-in-the-canal” devices that comprise 80 percent of the U.S. market. 

Perhaps in an effort to distance themselves from the “look” and “feel” of traditional hearing aids, they also sacrifice battery life, wireless connectivity, and own-voice occlusion when independent custom styles are used. Other manufacturers (FIGURE 3) use “hard-wired” connectivity between ears to improve wireless functionality and battery life.

FIGURE 4. REAR (green, purple), REUR (orange), and MPO (teal) curves for the Bose Hearphone device using the Audioscan Verifit REM system and the ISTS (REAR, REUR) and swept sinusoid (MPO) stimuli.
FIGURE 4. REAR (green, purple), REUR (orange), and MPO (teal) curves for the Bose Hearphone device using the Audioscan Verifit REM system and the ISTS (REAR, REUR) and swept sinusoid (MPO) stimuli.

Another area of convergence between hearables and hearing aids pertains to “acoustic transparency”—providing gain to replace insertion loss when the device is inserted into the ear. Compensation for the combined acoustic effects of ear canal resonance, venting, and microphone location effects to provide “natural” sound quality for ambient sounds will be crucial for success with full-time use of hearables beyond “streaming only” use. This will be essential for bridging the gap from situational use to PSAP/OTC use for more than a few hours at a time. 

FIGURE 4 illustrates REM findings from the Bose Hearphone devices when the on-board microphones (World Volume) were adjusted to their midpoint via the Bose Hear application. REAR (green, purple), REUR (orange), and MPO (teal) curves reveal reasonable acoustic transparency may be achieved with minimal adjustment of bass/treble and gain settings within the user application. 

Moving Beyond the Audiogram

While the new category of OTC hearing aids will be restricted for use in adult populations with mild-to-moderate sensorineural hearing loss, it remains to be seen exactly how they will define (and restrict) applications to persons that meet those candidacy requirements. Specifically, it is uncertain whether gain and output will be limited, or only maximum output limits consistent with the Make Listening Safe Initiative of the World Health Organization (2015), in association with the International Telecommunications Union, which currently recommend that levels not exceed 100 dB (A) measured on KEMAR or in-situ.

FIGURE 5. User application controls for Nuheara Boost and Bose Hearphone devices.
FIGURE 5. User application controls for Nuheara Boost and Bose Hearphone devices. 

In addition, because no physician waiver or audiological evaluation will be required before purchase of OTC devices, it portends that some manufacturers of PSAPs will begin to develop fitting strategies for setting gain/output and bass/treble of “world volume” levels that are based on end-user preference, rather than audiometric characteristics (FIGURE 5). 

Presumably, when the FDA issues its final ruling, these devices may well transition from PSAP to OTC devices using the same behavioral fitting methods over threshold-based prescriptive approaches. In fact, research suggests that people are able to adjust their hearing aid settings using a variety of user interfaces (with and without the benefit of audiometric threshold testing), and, in general, they prefer their own settings to those based on a prescriptive fitting formula or adjusted by an audiologist (Zakis et al, 2007). 

Additional research is required, however, to determine the optimal methods for self-assessment and fitting of OTC devices to maximize comfort, audibility and sound quality. For now, however, it appears as though behavioral methods for initial fitting and/or fine-tuning will augment (or even replace?!) prescriptive approaches. In the future, it may even be possible to record EEG directly from embedded sensors in hearing aids or hearables for a variety of applications, including brainstem auditory-evoked responses (BAER) for objective hearing assessment.


The hearing aid industry is in the midst of a “perfect storm” of changing technology, demographics, and distribution models. If the emergence of PSAPs and OTC devices increases awareness of the importance of hearing and increases market penetration beyond today’s 30 percent rate, it will be a tremendous boon for our profession. Technology is driving drastic (and disruptive) change to the traditional practice of audiology. Our patients—now customers— presently have access to the same information that we once controlled; the rise of health-care consumerism is akin to an Enchanted Forest of threats that may also provide opportunity if we focus on the value of our professional services, rather than simply the technology. It may turn out that we had the power all along.  


The views and opinions expressed in this article are those of the author and do not necessarily represent the official policy, position, or opinion of the American Academy of Audiology; further, the Academy does not endorse any products or services mentioned in this article.


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