Do Hearing Aids Need Real-Ear Verification? A 105-User Study

A retrospective study of 105 hearing aid users found no statistically significant three-month outcome difference between real-ear measurement fitting and a manufacturer first-fit refined by routine fine-tuning.

When an audiologist fits a hearing aid, the gold-standard step is called real-ear measurement: a thin probe microphone is placed in the ear canal to verify that the device is delivering the prescribed sound levels for that specific ear. It takes equipment, training, and clinic time, and surveys have long shown that many clinics skip it.

How much does that verification step actually change outcomes for the wearer? A new study from hearing clinics in South Korea, published in PLoS One, compared users fitted with real-ear measurement against users who started from the manufacturer's automatic first-fit and were then fine-tuned over follow-up visits, and the short-term results were closer than many would expect.

Background: Why the Researchers Looked at This

Every hearing aid must be programmed to match its wearer's hearing loss. Manufacturers supply an automatic starting point known as a first-fit, calculated from the person's audiogram. Real-ear measurement, often shortened to REM, goes further: it checks the sound actually arriving at the eardrum, because every ear canal shapes sound a little differently, and adjusts the device until output matches prescription targets.

Professional guidelines encourage REM, and studies have shown first-fit settings often deviate from targets. Yet evidence that REM produces better real-world outcomes has been mixed, especially for people who wear a hearing aid in only one ear. Those unilateral users are an interesting group, because their unaided ear still contributes to hearing, and how well that other ear works might influence how much benefit they perceive.

The research team set out to compare the two fitting pathways in unilateral users, and to test whether hearing in the opposite ear predicted results.

How the Study Was Done

The researchers reviewed records of 105 adults fitted with a single hearing aid who completed three months of follow-up. Sixty had been fitted using REM verification; 45 had started from the manufacturer first-fit and received routine fine-tuning at clinic visits instead.

Outcomes covered both measurement and experience. Functional gain testing measured how much softer a sound the person could hear with the aid in place, expressed in decibels. Two questionnaires captured the wearer's own view: the Hearing Handicap Inventory for the Elderly, which scores how much hearing difficulty intrudes on daily and social life, and the International Outcome Inventory for Hearing Aids, a standard satisfaction and benefit measure.

Statistical models then adjusted the comparisons for age, sex, and hearing thresholds, and separate analyses tested whether hearing in the unaided ear correlated with improvement.

What the Researchers Found

At three months, the REM group averaged 11.0 decibels of functional gain against 9.1 decibels in the first-fit group, a difference that did not reach statistical significance. Reported handicap fell substantially in both groups, by an average of 25.7 points with REM and 32.9 points without, again with no significant difference between pathways. Satisfaction scores were nearly identical, at 24.4 and 23.9 points.

After adjusting for patient differences, the fitting method still showed no association with either questionnaire outcome. Whatever advantages REM confers in matching prescription targets, they did not translate into measurably better three-month results in this cohort.

The clearest signal in the data involved the other ear. Participants with worse hearing in the unaided ear reported greater improvement in handicap scores, a moderate correlation that was highly statistically significant. People who depended more on the aided ear, in other words, felt the aid's benefit more strongly.

The authors are careful about what the numbers do not show. A retrospective comparison of this size cannot prove the two methods are equivalent; it can only report that no significant difference emerged.

What It Means for People with Hearing Loss

For wearers, the encouraging news is that both pathways delivered real improvement: large drops in reported handicap and meaningful gain within three months. The study suggests that a careful process of starting from a prescription-based fit and refining it over follow-up can serve users well, at least in the short term, even without probe-microphone verification.

The contralateral-ear finding also carries a counseling message. Someone whose other ear still hears well may notice less dramatic change from a single hearing aid, and that expectation is worth setting honestly at the start rather than discovering with disappointment later.

When the Starting Fit Carries More of the Load

Because this study found that a well-designed initial fit refined over time held its own against clinic-verified fitting in the short term, it speaks to a question many people now face: how far can carefully automated fitting go? Newer FDA-OTC hearing aids are built on exactly that premise 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 designed for clearer speech in noisy environments. Its optional companion app can run a frequency-specific hearing check through the aid itself, a form of app-based hearing personalization that tailors gain and frequency response to your hearing profile, and the aid also works out of the box without the app or the test. It runs 20 hours per charge, with a case holding three additional full charges for 80 hours total, streams calls, TV, and music over Bluetooth, and comes with a 5-year warranty and a 45-day trial that begins when the device arrives.

The boundary from this research still applies: OTC devices are approved for mild to moderate loss, and people with severe or profound loss benefit most from clinical fittings. Details are at pandahearing.com/products/panda-hearing-aids-quantum.

Limitations of This Research

This was a retrospective study, so patients were not randomly assigned to fitting methods, and unmeasured differences between groups could influence results. Follow-up lasted only three months, outcomes were measured at a single point, and the modest sample came from a small number of clinics in one country. As the authors note, finding no significant difference is not the same as proving the approaches equal, and the study was not designed to isolate the effect of REM itself.

The authors declared no competing interests.

Where This Leaves Us

Fitting verification remains good clinical practice, and nothing here argues against it. But this study adds to a growing body of evidence that thoughtful starting fits plus follow-up adjustment can deliver strong early outcomes, and it reminds both clinicians and wearers that the ear without the device shapes how the one with it is experienced.

Lee JM, Kong TH, Lee JW, Lee HJ. Outcomes of real-ear measurement-based fitting in unilateral hearing aid users: Influence of contralateral hearing. PLoS One. 2026;21(9):e0358875. Retrieved from PubMed. https://doi.org/10.1371/journal.pone.0358875