You can absolutely buy just one hearing aid, and for certain types of hearing loss it is the clinically appropriate choice. But for the most common scenario, where both ears have similar levels of hearing loss, research consistently shows that wearing two hearing aids produces better outcomes than wearing one. The question is not really whether you’re allowed to buy a single device; it’s whether doing so costs you something in terms of how well you hear, how your brain adapts over time, and how safe you feel navigating everyday environments.
Why Two Hearing Aids Are the Standard Recommendation
Your brain figures out where sounds are coming from by comparing what arrives at each ear. Two cues do most of the heavy lifting: tiny differences in when a sound reaches each ear, and tiny differences in how loud it is at each ear. These interaural time and level differences are how you instinctively turn your head toward someone calling your name or step out of the way when a car approaches from the side.1PubMed. Different patterns of human discrimination learning for two interaural cues to sound-source location When only one ear is amplified, those comparisons break down. You lose much of your ability to locate sounds in space, and the world can start to feel flat and directionless.
Binaural hearing also plays a critical role in noisy settings. The brain uses input from both ears to separate a voice you want to hear from the background chatter, a process sometimes called the cocktail-party effect. Losing that ability, even partially, makes restaurants, meetings, and busy streets significantly harder to navigate.2PubMed Central. A common periodic representation of interaural time differences in mammalian cortex People with hearing in only one functional ear report difficulty understanding speech in noise because they lose the redundancy and spatial processing that two working ears provide.3PubMed. Understanding speech in noise after correction of congenital unilateral aural atresia: effects of age in the emergence of binaural squelch but not in use of head-shadow
There is also a straightforward volume benefit. When both ears are working together, you effectively hear soft sounds about 2 decibels better than you would with one ear alone. That might not sound like much, but at the threshold of hearing, it is equivalent to doubling the length of time a sound plays.4PubMed Central. Towards a unifying basis of auditory thresholds: binaural summation In practical terms, two aids let you keep the volume lower on each one, which tends to make sound quality more natural and less fatiguing.
When One Hearing Aid Is the Right Call
Not everyone has the same hearing loss in both ears. Asymmetric hearing loss, where one ear is substantially worse than the other, is common. In these cases, fitting only the worse ear or only the better ear is a legitimate clinical strategy rather than a compromise. A study of patients with asymmetric loss who were fitted with a single aid in the worse ear found that about two-thirds continued using the device, though only about 43% met the researchers’ definition of “success” on outcome measures.5PubMed Central. Predictable Factors of People with Asymmetrical Hearing Loss Wearing a Hearing Aid in the Worse Ear Only That is a real but modest success rate, and it underscores that the decision about which ear to amplify matters a great deal when you are only buying one device.
Single-sided deafness, where one ear has no usable hearing at all, is another clear case for a single-device approach, though the device involved is often specialized. Standard hearing aids cannot restore hearing to a dead ear. Instead, a CROS (Contralateral Routing of Signal) hearing aid picks up sound on the deaf side and wirelessly sends it to the functioning ear, reducing the “head shadow” effect that blocks sounds coming from your deaf side.6PubMed Central. Nonsurgical Management of Single-Sided Deafness: Contralateral Routing of Signal If the better ear also has some hearing loss, a BiCROS system does the same routing while also amplifying sound for that ear. Research continues to investigate how well these devices reduce listening effort over time.7PubMed Central. Longitudinal Evaluation of Listening Effort and Speech Perception in Noise in CROS and BiCROS Hearing Aid Users With Single-Sided Deafness
Bone-anchored hearing aids are another option when conventional devices are not suitable. These surgically placed devices transmit sound through the skull bone to the functioning inner ear and have been shown to produce good audiological results for people with asymmetric hearing loss.8PubMed Central. Bone Anchored Hearing Aids for the Treatment of Asymmetric Hearing Loss They can also partially restore some spatial hearing benefits for people with single-sided deafness.9PubMed. Efficacy of Bone-Anchored Hearing Aids in Single-Sided Deafness: A Systematic Review
The Auditory Deprivation Problem
One of the strongest arguments against buying a single hearing aid when both ears need help is a phenomenon called auditory deprivation. When one ear consistently receives amplified sound while the other sits idle, the unaided ear can gradually lose its ability to process speech, even if the underlying hearing level stays the same. The ear’s hardware does not change, but the brain’s ability to make sense of what that ear sends it deteriorates from disuse.
Research on patients who wore a single hearing aid for symmetric hearing loss found that bilateral aids are strongly recommended, particularly for people with moderate to severe loss, specifically to prevent this deprivation effect in the unaided ear.10PubMed Central. Which Patients With a Unilateral Hearing Aid for Symmetric Sensorineural Hearing Loss Have Auditory Deprivation? The concern is not hypothetical. If you wear one aid for years and later decide to add a second, the neglected ear may not respond as well to amplification as it would have if you had fitted it from the start. This makes the single-aid decision less reversible than it might seem.
The Mild-to-Moderate Exception
Here is where the picture gets more nuanced than the “always buy two” message suggests. For people with mild or moderate hearing loss in both ears, the gap between one and two hearing aids may be smaller than you would expect. A large comparative effectiveness study funded by the Patient-Centered Outcomes Research Institute followed adults with mild to moderate bilateral hearing loss and found that at three months and six months, there were no significant differences between the one-aid and two-aid groups on quality of life related to hearing, daily hours of use, satisfaction, or overall effectiveness.11Patient-Centered Outcomes Research Institute. Comparing the Use of One Versus Two Hearing Aids in Adults with Mild or Moderate Hearing Loss
That result surprises a lot of people, and it deserves context. People with mild to moderate loss still have a fair amount of natural hearing to work with. Their unaided ear is not sitting in silence; it is still picking up sounds and contributing to localization and speech understanding, just not as well as it could. For these individuals, the marginal benefit of a second device, while real in laboratory tests, may not translate into a noticeable improvement in daily life that shows up on satisfaction questionnaires. This does not mean two aids are pointless for mild loss; it means the urgency is lower, and the cost-benefit math is different.
A large study of U.S. veterans confirmed that bilateral fittings yield the best overall outcomes across both short and long-term measures and that there was no hearing loss configuration for which a bilateral fitting led to worse results. However, the same study found that if a single aid was going to be used, fitting the better ear produced higher rates of long-term continued use compared to fitting the worse ear.12PubMed Central. Fitting a Hearing Aid on the Better Ear, Worse Ear, or Both: Associations of Hearing-aid Fitting Laterality with Outcomes in a Large Sample of US Veterans That finding makes intuitive sense: the better ear already has a processing advantage, and amplification adds to an existing strength rather than trying to compensate for a greater deficit.
Which Ear to Fit If You Choose One
This is a question that trips up both patients and some clinicians. The instinct is to help the weaker ear, but the evidence suggests the answer depends on the pattern of your hearing loss. For symmetric loss, the veterans study found better long-term persistence when the better ear was fitted. For asymmetric loss with meaningful hearing in both ears, fitting the worse ear had a lower success rate but still helped some patients hear in situations they otherwise could not manage.5PubMed Central. Predictable Factors of People with Asymmetrical Hearing Loss Wearing a Hearing Aid in the Worse Ear Only
There is no universal rule because the decision depends on your specific audiogram, your daily listening demands, and which ear your brain relies on more. An audiologist can run speech-recognition tests on each ear separately to see which one is the better candidate. If you are buying a single aid without professional fitting, such as through the over-the-counter market, you will not have that guidance, which is one reason professionals recommend at least an initial evaluation even if you plan to purchase on your own.
What One Hearing Aid Does to Your Brain Over Time
Long-term monaural hearing aid use physically changes how the auditory brainstem responds to sound. A study of elderly people who had worn a single hearing aid for an extended period found measurable asymmetries between the aided and unaided ears. The ear with hearing aid experience showed elevated acoustic reflex thresholds by 2 to 9 decibels, and this change occurred at the brainstem level regardless of which ear was being stimulated.13NeuroReport. Evidence for adaptive plasticity in elderly monaural hearing aid users In other words, wearing a hearing aid in one ear actually rewired the brain’s early processing in ways that made the two ears respond differently even to identical sounds.
This plasticity is a double-edged sword. It shows the brain is remarkably good at adapting to whatever input it gets, but it also means a single-aid fitting creates a new normal that could make adding a second aid later feel strange. The aided ear adapts to amplification while the unaided ear adapts to relative silence. The longer this goes on, the harder it becomes to re-balance the system.
The Listening Effort Factor
Even when you can technically understand what someone is saying, doing so with impaired hearing costs mental energy. This cognitive load builds up over a day and contributes to the fatigue that many people with hearing loss report by evening. Research on binaural hearing aid technology that coordinates processing between both ears has shown meaningful reductions in listening effort, including faster reaction times on secondary tasks and changes in brain activity patterns consistent with reduced cognitive load.14Nature. Reduced listening effort with adaptive binaural beamforming in realistic noisy environments
This is a benefit you cannot easily measure with a hearing test. Two coordinated hearing aids can share information and apply directional processing together, narrowing their focus onto a speaker in front of you while suppressing noise from the sides and behind. A single hearing aid has to do all its processing in isolation. For someone who spends much of their day in conversation, meetings, or social settings, that difference in mental fatigue can be substantial even if both setups let you “hear” the same words.
Preference and Satisfaction in Real Life
People who try both options tend to prefer two hearing aids and report better real-world outcomes than those who prefer one.15PubMed Central. Preference for one or two hearing AIDS among adult patients But preference is not the same as necessity, and the degree of advantage depends heavily on the severity and symmetry of the loss, the listening environments a person encounters, and individual sensitivity to spatial cues.
Cost is a legitimate factor in this decision. Hearing aids remain expensive, and many people face limited insurance coverage. Qualitative research on hearing aid users has found that while some describe the devices as a worthwhile investment, others experience real financial burden due to high costs and thin insurance support.16Journal of the American Academy of Audiology. Adult Hearing Aid Users’ Perspectives on Outcome Expectations and Perceived Value for Money: A Qualitative Study Using the Health Belief Model Buying one hearing aid instead of two roughly halves the upfront cost, and for someone with mild bilateral loss, the PCORI data suggest the real-world sacrifice may be minimal. For someone with moderate to severe bilateral loss, however, that savings comes with the risk of auditory deprivation and meaningfully worse performance in noise.
Balance and Spatial Awareness
A benefit of binaural hearing that rarely makes it into consumer marketing materials is its contribution to balance. Your brain uses spatial sound cues as one input for maintaining postural stability. Research measuring body sway found a significant improvement in balance when spatial auditory cues were present. During one standing-balance test, spatial sound reduced mean sway by about 9%, and during a stepping test, spatial auditory cues reduced mean body sway by roughly 76%.17PubMed. Relationship between postural stability and spatial hearing
For older adults, who make up the largest group of hearing aid users and who face the greatest fall risk, this connection between hearing and balance is worth taking seriously. A single hearing aid restores some auditory spatial information but not the full binaural picture. Whether that partial restoration is enough to improve balance has not been studied as thoroughly, but the principle is clear: the more complete the spatial hearing, the more stable you are on your feet.
Tinnitus and Amplification Strategies
Many people who need hearing aids also have tinnitus, and hearing aids are one of the most commonly recommended management tools for ringing in the ears. The logic is that amplifying environmental sounds partially masks the tinnitus signal and reduces its perceived loudness. Research comparing different amplification strategies found significant differences in how well various fitting programs provided tinnitus relief, with broader amplification profiles tending to perform better than narrower ones.18PubMed Central. Amplification Strategies to Reduce Tinnitus: A Paired Comparison Method
If your tinnitus is only in one ear, a single hearing aid on that side may be sufficient for relief. If it occurs in both ears, which is more common, two aids provide more consistent masking throughout the day. Some hearing aids include built-in tinnitus sound generators that play white noise or other soothing sounds, and these work independently in each ear. For bilateral tinnitus management, two devices give you independent control of the masking signal in each ear, which is difficult to replicate with a single unit.
The Occlusion Effect and Comfort
One practical annoyance that sometimes drives people toward wearing fewer hearing aids is the occlusion effect: when a hearing aid or earmold plugs the ear canal, your own voice, chewing, and even your heartbeat can sound boomy and unnatural. Research has measured the occlusion effect reaching about 40 decibels at very low frequencies, and in some individuals, the heartbeat became audible when the ear canal was blocked.19PubMed Central. A technique for estimating the occlusion effect for frequencies below 125 Hz Open-fit hearing aids with vented domes largely solve this problem, but not everyone is a candidate for open fittings, particularly those with more severe low-frequency loss who need a tighter seal to prevent feedback.
If the occlusion effect is intolerable in both ears, wearing one aid while leaving the other ear open is a compromise some people find acceptable. It reduces the sensation of being plugged up while still providing amplification on one side. This is not the ideal audiological solution, but comfort matters: a hearing aid sitting in a drawer because it feels awful is worse than a single hearing aid you actually wear. Audiologists generally prefer you wear one aid consistently over wearing two intermittently.