What 59 Studies Say About OTC Hearing Aids and Health Sensors

A new PRISMA-guided review finds that self-fitted over-the-counter hearing aids matched professionally fitted devices in most clinical trials, while built-in health sensors remain promising but clinically unproven.

In 2022, the United States opened a new front door to hearing care. A federal rule created an over-the-counter category of hearing aids that adults with mild-to-moderate hearing loss can buy directly, without a prescription, an exam, or a professional fitting. Four years on, researchers are now able to ask a question that was purely hypothetical at launch: does the evidence show that this new pathway actually works?

A new review from the Technical University of Munich takes stock of that evidence. It also examines a second, quieter shift in the field: hearing aids that double as health monitors, tracking things like movement, heart rate, and temperature from a device already worn all day.

Background: Why the Researchers Looked at This

The FDA's 2022 rule on FDA-OTC hearing aids was designed to address a long-standing access problem: most adults who could benefit from hearing aids never get them, with cost and the need for clinic visits among the most cited barriers. The rule allows devices for mild-to-moderate hearing loss to be sold directly to consumers, many of them designed to be self-fitted. Self-fitting means the user, rather than an audiologist, adjusts the device to their own hearing, often guided by an app or an in-device hearing check.

That raises an obvious clinical question: can people really fit their own hearing aids well? Early skepticism was reasonable. Fitting a hearing aid involves setting amplification differently across frequencies to match a person's specific hearing profile, something traditionally done in a sound booth.

At the same time, manufacturers have begun embedding health sensors into hearing aids. Because the ear canal is a stable site for measurement and hearing aids are worn for many hours a day, they are attractive platforms for tracking gait, activity, and vital signs. The Munich team wanted to know how much of this is validated science versus marketing.

How the Study Was Done

The authors conducted a narrative review guided by PRISMA, a standard framework for systematically identifying and reporting research. They searched four major databases, PubMed, Scopus, Web of Science, and the Cochrane Library, for studies published between 2020 and 2026.

Fifty-nine studies met their criteria. These covered two broad areas: clinical evidence on over-the-counter and self-fitting hearing aids, including randomized trials comparing self-fitting to professional fitting, and validation studies of health-monitoring sensors built into hearing aids. The authors then synthesized what the combined evidence shows and where it falls short.

What the Researchers Found

On the central question, the evidence was largely positive. In most randomized trials, self-fitted over-the-counter hearing aids produced outcomes that were noninferior to professionally fitted devices. In plain terms, people who set up the devices themselves generally did about as well as people fitted by a professional. One trial was the exception, finding that audiologist-fitted hearing aids achieved better results.

Adoption, however, has been slower than the trial results might suggest. The review describes consumer uptake as incremental, and notably, most over-the-counter users still ended up seeking some form of professional support rather than managing everything alone.

Usability emerged as a real weak point. In usability assessments, many older adults had difficulty completing self-fitting tasks without error, and the authors caution that current self-fitting interfaces may not reliably guide users to their best amplification settings.

On the sensor side, the technical results were stronger than expected. Accelerometry-based sensors in hearing aids measured gait and energy expenditure with accuracy comparable to established reference instruments and consumer wearables. A prototype multi-sensor platform successfully measured temperature, oxygen saturation, heart rate, and respiration rate from the ear.

The critical gap: not a single study has yet linked hearing aid sensor data to improved patient outcomes. The sensors are technically validated but clinically unproven.

What It Means for People with Hearing Loss

For adults with mild-to-moderate hearing loss, the trial evidence supports self-fitting as a legitimate route to well-adjusted hearing aids, not a second-class compromise. That matters, because the self-fit route is typically far less expensive and far more convenient than clinic-based care.

The usability findings add a practical footnote: setup design matters, and devices that work well even without an app-driven process, or that make that process optional, better fit how many older adults actually use technology. The finding that most buyers still sought some professional support suggests the future is a blend of self-service and expert help rather than one replacing the other.

As for health sensors, the sensible takeaway is to treat them as a bonus rather than a reason to buy. The measurements appear accurate, but no one has yet shown they improve health outcomes.

Self-Fitting Held Up in Trials: What That Looks Like in Practice

Because the review found self-fitted devices matched professionally fitted ones in most randomized trials, it strengthens the case for FDA-OTC hearing aids as a first step for adults with mild-to-moderate hearing loss. Panda Quantum is one such device, a 16-channel receiver-in-canal hearing aid with adaptive noise reduction built for clearer speech in noisy environments.

The self-fitting approach the review evaluated is similar in spirit to the optional app-based hearing personalization Quantum offers. An optional in-ear hearing test, run through the aid itself, can measure hearing at specific frequencies and tune gain and frequency response to the user's profile. The aid also works out of the box without the app or the test, which matters given the review's finding that some older adults struggle with app-driven setup.

Quantum runs 20 hours per charge, with a case providing three additional full charges for 80 hours total, streams calls, TV, and music over Bluetooth, and carries a 5-year warranty with a 45-day trial that begins when the customer receives the product. One caveat the research supports: over-the-counter devices are approved for mild-to-moderate loss, and severe or profound loss still benefits most from clinical fittings.

Limitations of This Research

This is a narrative review rather than a full meta-analysis, so the authors synthesized findings qualitatively instead of pooling data statistically, even though study identification followed PRISMA guidance. The 59 included studies varied in design and quality, and the sensor validation work in particular involved small samples and, in one case, a prototype device not yet on the market.

The review also reflects a fast-moving market: devices released after the search window closed are not represented, and long-term outcomes with over-the-counter devices remain thinly studied.

Where This Leaves Us

Four years into the over-the-counter era, the core promise appears to be holding: in most trials, people can self-fit hearing aids to a standard comparable to professional care, even as design gaps in setup interfaces and the unproven clinical value of built-in health sensors mark out the field's next challenges.

Itatani N, Zavaglia M. Over-the-counter hearing aids and integrated health-monitoring sensors: a review of clinical evidence and implementation. Frontiers in Digital Health. 2026;8:1771022. Retrieved from PubMed. https://doi.org/10.3389/fdgth.2026.1771022