One hearing aid or two for age-related hearing loss?

“Do I need two hearing aids, or would one be enough?”

For adults seeking help for age-related hearing loss, this is a practical question with implications for both everyday communication and treatment costs.

Our randomized clinical trial, published in JAMA Otolaryngology–Head & Neck Surgery, examined this question in adults with bilateral, symmetrical mild to moderate sensorineural hearing loss. At three months, participants assigned to bilateral hearing aids reported greater benefit, on average, than those assigned to a unilateral hearing aid.

Both configurations produced benefit in the trial, including clinically meaningful improvement for some individual participants. However, whether the average difference between the groups is clinically meaningful remains uncertain.

Why this comparison matters

Bilateral hearing aids are commonly recommended for age-related hearing loss. Laboratory research provides evidence of advantages over unilateral amplification, including better localization and speech understanding in some noisy listening conditions. However, evidence directly comparing the effectiveness of the two configurations in clinical practice has been limited.

Earlier studies often included small samples or participants with widely differing hearing losses and hearing aid experience. Much of the evidence also predates contemporary hearing aid technology. Adults with mild hearing loss have been underrepresented, even though they frequently face this fitting decision.

We designed our trial to address these gaps using commercially available prescription hearing aids and care delivered through audiology clinics. Participants paid for their hearing aids and audiologic services, with a manufacturer discount on devices and insurance benefits where applicable. This preserved a financial consideration that is often removed when study devices are provided free of charge.

A trial reflecting clinical care

The study was conducted at Duke University Health System and Vanderbilt University from 2021 to 2024.

• Participants: The analysis included 275 adults aged 50 years or older, with a mean age of approximately 71 years. Participants had no more than three months of prior hearing aid use and were willing to try either fitting configuration.
• Hearing loss: Approximately 89% had mild hearing loss in the better ear.
• Fitting options: Participants were randomly assigned to a unilateral hearing aid or bilateral hearing aids for three months. They selected Phonak receiver-in-the-canal devices at standard or advanced technology levels, with coupling appropriate to their needs.
• Clinical care: Fittings and follow-up appointments were delivered as part of standard clinical care. For unilateral fittings, the ear was selected according to the audiologist’s recommendation and the participant’s needs or preference.

Our primary outcome was benefit measured with the Abbreviated Profile of Hearing Aid Benefit (APHAB). The APHAB-global score captures how frequently people experience communication problems in everyday listening. We calculated benefit by subtracting the aided score at three months from the unaided baseline score. A higher benefit score therefore indicates a greater reduction in reported problems.

Greater average benefit with bilateral hearing aids

The mean APHAB-global benefit score was 19.74 percentage points in the bilateral group and 14.41 percentage points in the unilateral group. After adjustment for clinical site, the average difference was 5.29 percentage points in favor of bilateral hearing aids (95% confidence interval, 1.80 to 8.79; P = .003).

This was a statistically significant difference. Its clinical meaningfulness needs further investigation. The observed difference was smaller than the 10-point difference assumed when planning the study, and the threshold for a clinically meaningful between-group difference remains unresolved.

We also examined treatment response using reductions of at least 15 or at least 25 percentage points in APHAB-global scores. Under both definitions, a greater proportion of participants in the bilateral group met the response criterion. Using the 15-point criterion, 57.8% of eligible bilateral participants were responders, compared with 41.6% of eligible unilateral participants. With the 25-point criterion, the proportions were 43.4% and 28.3%, respectively.

These percentages require context. Participants whose baseline scores were too low to achieve the specified reduction were excluded from the corresponding responder analysis. Participants with missing three-month scores were counted as nonresponders. The criteria describe individual treatment response and do not establish the clinical meaningfulness of the average difference between fitting configurations.

Additional outcomes provide a fuller picture

Participants assigned to bilateral hearing aids reported less residual aided difficulty on the Glasgow Hearing Aid Benefit Profile. They also reported greater improvement on the Speech, Spatial and Qualities of Hearing scale.

For the remaining secondary outcomes, between-group differences were generally small, with confidence intervals consistent with little or no difference. These included overall hearing aid satisfaction and daily use. The speech-in-noise test, which presented speech and noise from the same location, did not show a statistically significant difference between groups. This test arrangement does not resolve whether bilateral advantages would emerge in other spatial listening conditions.

Secondary analyses were not adjusted for multiple comparisons, so these findings should be interpreted with appropriate caution.

Where do the findings apply?

The findings are most directly relevant to adults starting hearing aid use for bilateral, symmetrical mild to moderate age-related hearing loss. The sample was predominantly White and highly educated, which limits generalizability to broader populations. The trial used one manufacturer’s devices and a parallel-group design, so each participant’s outcomes were assessed with their assigned configuration rather than through a within-person comparison of both options.

Participants knew whether they received one or two hearing aids. Study audiologists were blinded to patient-reported outcome scores, and site principal investigators remained blinded to the data until planned analyses were completed. The primary endpoint was three months, leaving longer-term effectiveness open to further study. The trial also did not establish effects on broader health outcomes.

Our results add evidence that bilateral fitting provides greater self-reported benefit on average. They inform, but do not yet establish, a standard-of-practice recommendation for bilateral fitting.

What does this mean for clinical conversations?

These findings can help us discuss fitting options with patients. Here are a few points to consider when bringing the evidence into those conversations.

• Two hearing aids offered greater benefit on average. At three months, participants using bilateral hearing aids reported greater benefit than those using one. We can share this finding while explaining that the clinical meaningfulness of the average difference remains uncertain.
  
• One hearing aid can still provide meaningful benefit. Some participants using a unilateral hearing aid achieved clinically meaningful improvement. This gives us room to discuss individual options, while being clear that the study does not show that one hearing aid provides the same benefit as two.
  
• Follow up on the person’s experience. Asking about communication difficulties before fitting and again after a period of use can help us understand what has changed for that person. The average results cannot tell us how much benefit an individual will experience.
  
• Make space for cost and preferences. Participants paid for their hearing aids and services, with a manufacturer discount on devices and insurance benefits where applicable. The study did not establish which configuration is more cost-effective. Its findings can inform a discussion that also takes account of the person’s listening needs and financial circumstances.

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We invite you to learn more – Read the article.

Study funding and support
The study was funded by the Patient-Centered Outcomes Research Institute (PCORI). Sonova (Phonak) supported access to study devices and provided an extended trial period. Full funding and disclosure details are available in the published paper.

Reference

Smith, S. L., Ricketts, T. A., Kilpatrick, K. W., North, R., Bettger, J. P., Coles, T., Eberts, S., Peskoe, S. B., Francis, H. W., Toth, H., Dillon, W., Thompson, L., Branscome, K., Walker, A., & Rockhold, F. W. (2026). Unilateral and bilateral hearing aids for age-related hearing loss: A randomized clinical trial. JAMA Otolaryngology–Head & Neck Surgery. Advance online publication. https://doi.org/10.1001/jamaoto.2026.2401