Why Is Hearing Worse in One Ear? Unilateral and Asymmetric Hearing Loss Explained

Have you ever noticed that sounds seem clearer in one ear than the other?

Perhaps phone conversations sound different depending on which ear you're using. Or you find it easier to understand someone when they're sitting on a particular side of you.

Hearing doesn't always change equally in both ears.

In audiology, differences between the ears are described using terms such as unilateral hearing loss, asymmetric hearing loss, and single-sided deafness.

Although these terms are related, they don't always mean the same thing.

According to the American Speech-Language-Hearing Association (ASHA), hearing loss may affect one ear or both ears, and the degree and pattern of hearing loss can differ between them.

These differences can affect everyday listening, including understanding conversations in noisy places and recognizing where sounds are coming from.

This article explains the terminology, documented causes, hearing-related effects, and published research on unequal hearing between the ears.

What Does It Mean When One Ear Hears Better Than the Other?

Hearing sensitivity can vary between the left and right ears.

In some people, one ear has hearing thresholds within the typical range while the other has measurable hearing loss.

In others, both ears have hearing loss, but one is more affected.

Hearing differences may involve:

• The overall degree of hearing loss
• The frequencies affected
• Speech recognition ability
• The type of hearing loss
• How hearing changes over time

Audiologists describe these characteristics separately because each provides different information.

For example, a person might have mild hearing loss in one ear and moderate hearing loss in the other.

Another individual might have relatively similar hearing thresholds at low frequencies but a substantial difference at higher frequencies.

The presence of a difference does not, by itself, identify the underlying cause.

Source: ASHA — Hearing Loss in Adults

Unilateral vs. Asymmetric Hearing Loss: What's the Difference?

These terms describe related but different hearing patterns.

Unilateral hearing loss

Unilateral hearing loss, commonly abbreviated UHL, refers to hearing loss affecting one ear while the other ear has hearing within the normal range.

ASHA explains that unilateral hearing loss can range from a relatively small hearing difference to a complete loss of hearing in one ear.

It can occur in both children and adults.

Asymmetric hearing loss

Asymmetric, or asymmetrical, hearing loss refers to a difference in hearing ability between the two ears.

The difference may involve the degree of hearing loss, the configuration across frequencies, or both.

Both ears may have hearing loss, but to different extents.

Single-sided deafness

Single-sided deafness (SSD) describes little or no functional hearing in one ear.

In many definitions, the other ear has normal or near-normal hearing.

Some specialist clinical services also use the term for people whose better ear has some hearing impairment.

The terminology can therefore vary according to the clinical setting.

Side-by-side comparison

These descriptions can overlap.

For instance, unilateral hearing loss also creates a difference between ears, but in audiological reporting, the two terms may be used to emphasize different characteristics.

Sources:

• ASHA — Hearing Loss in Adults
• ASHA — Unilateral Hearing Loss
• Cambridge University Hospitals — Single-Sided Deafness

What Are the Possible Causes of Hearing Loss in One Ear?

Hearing differences can arise from several conditions and factors.

Some involve sound transmission through the outer or middle ear.

Others involve the inner ear, auditory nerve, or broader auditory system.

According to ASHA and the U.S. National Library of Medicine, documented causes include the following.

1. Earwax blockage

Earwax normally helps protect the ear canal.

However, excessive buildup can obstruct the passage of sound.

If substantial blockage affects one ear more than the other, hearing may seem different between the two sides.

Earwax obstruction is an example of a possible conductive cause of hearing loss.

Source: MedlinePlus — Earwax

2. Ear infections and middle-ear conditions

Infections, fluid, or structural problems affecting the middle ear may interfere with sound transmission.

Because these conditions do not necessarily affect both ears equally, they can contribute to one-sided or unequal hearing difficulties.

Different middle-ear conditions have different characteristics, and the pattern of hearing loss alone does not establish which condition is involved.

Source: ASHA — Hearing Loss in Adults

3. Exposure to loud noise

Loud sound exposure can damage the sensory structures involved in hearing.

Noise-related hearing loss is often bilateral, but differences between ears can occur depending on the exposure.

ASHA includes noise exposure among recognized potential causes of unilateral hearing loss.

Source: ASHA — Unilateral Hearing Loss

4. Head or ear injuries

Injuries involving the head, ear, or hearing-related structures can sometimes result in hearing loss.

The resulting hearing difficulties may affect one ear, both ears, or particular sound frequencies.

The characteristics depend on the nature of the injury and which structures are affected.

Source: MedlinePlus — Hearing Disorders and Deafness

5. Genetic and inherited factors

Some forms of hearing loss have genetic causes.

Inherited hearing differences may be present from birth or become apparent later.

ASHA identifies hereditary hearing loss and certain syndromes among possible causes of unilateral hearing loss.

Genetic hearing loss does not always produce the same hearing pattern in both ears.

Source: ASHA — Unilateral Hearing Loss

6. Certain inner-ear disorders

Conditions affecting the inner ear can produce hearing changes that differ between ears.

One example discussed by the NIDCD is Ménière's disease, which is associated with episodes of vertigo, tinnitus, and fluctuating hearing loss.

However, a difference between ears does not establish the presence of any particular inner-ear disorder.

Source: NIDCD — Sudden Deafness

7. Conditions involving the auditory nerve

Less commonly, hearing differences may be associated with conditions affecting the auditory nerve.

One example is vestibular schwannoma, a typically benign tumor involving the vestibulocochlear nerve.

It is important to distinguish the existence of this potential cause from its frequency.

Asymmetric hearing loss does not mean someone has a vestibular schwannoma.

A 2026 systematic review of studies involving patients referred for evaluation found that this diagnosis was uncommon among those undergoing imaging for asymmetric sensorineural hearing loss.

The research is discussed in more detail below.

Source: Strickland et al. — Congress of Neurological Surgeons Systematic Review, 2026

Why Does Hearing With Two Ears Matter?

Human hearing uses information from both ears to understand the surrounding sound environment.

This process is commonly described as binaural hearing.

The auditory system compares information arriving at each ear, including small differences in timing and sound level.

These differences help the brain determine where sounds originate.

Hearing with two ears also contributes to understanding speech when competing sounds are present.

According to ASHA, people with unilateral hearing loss may experience difficulties involving sound localization and speech understanding in noisy environments.

Source: ASHA — Unilateral Hearing Loss

How Can Hearing Loss in One Ear Affect Everyday Listening?

The effects vary depending on the degree, type, and configuration of hearing loss.

Research identifies several common listening challenges.

Difficulty identifying where sounds come from

Sound localization is the ability to determine the direction of a sound source.

For example, a person may recognize that someone is speaking but have difficulty identifying the direction of the voice.

A review published in the American Journal of Audiology in 2022 examined sound localization across different groups of listeners.

The review described reduced localization accuracy among people with asymmetrical and unilateral hearing loss compared with listeners whose hearing was more symmetrical.

This does not mean that every person with unequal hearing has the same degree of difficulty.

Source: Sound Localization of Listeners With Normal Hearing, Impaired Hearing, Hearing Aids, Bone-Anchored Hearing Instruments, and Cochlear Implants: A Review

Difficulty following conversations in background noise

Restaurants, offices, family gatherings, and other noisy settings contain multiple sound sources.

The ability to distinguish speech from competing noise involves information from both ears.

When that information is reduced or unequal, speech understanding can become more challenging.

Cambridge University Hospitals identifies difficulty separating speech from background noise as a characteristic commonly associated with single-sided deafness.

Source: Cambridge University Hospitals — Single-Sided Deafness

Difficulty hearing sounds from one side

When sound comes from the side of the poorer-hearing ear, the head itself can reduce the sound reaching the better-hearing ear.

This is known as the head shadow effect.

The effect is frequency dependent and can make certain sounds arriving from the affected side more difficult to detect.

Source: Cambridge University Hospitals — Single-Sided Deafness

Greater listening effort in some situations

ASHA identifies listening fatigue among possible hearing-loss experiences.

When understanding speech becomes more challenging, listening may require additional concentration.

However, the extent of any listening difficulty varies significantly among individuals.

Source: ASHA — Hearing Loss in Adults

Why Can Hearing in One Ear Seem Normal While the Other Ear Is Different?

People sometimes wonder why a hearing difference isn't immediately noticeable.

One explanation is that the better-hearing ear can continue detecting many everyday sounds.

In relatively quiet environments, that ear may provide sufficient sound information for comfortable communication.

Differences may become more apparent when:

• Sound comes from the poorer-hearing side.
• Multiple people are speaking.
• Background noise is present.
• The source of a sound needs to be identified.
• A sound is presented separately to one ear, such as during a telephone call.

ASHA notes that unilateral hearing loss can sometimes be difficult to recognize because one ear continues to have normal hearing.

The Cambridge University Hospitals audiology service similarly describes how people with single-sided deafness may have particular difficulty with sound direction and understanding speech in noise.

These are documented listening characteristics, not criteria for determining an individual's hearing status.

How Is Unequal Hearing Represented on an Audiogram?

An audiogram is a graph used to display hearing thresholds at different sound frequencies.

The horizontal axis generally shows frequency, measured in hertz (Hz).

The vertical axis shows hearing level, measured in decibels hearing level (dB HL).

Results from the right and left ears are displayed separately.

This allows an audiologist to compare hearing sensitivity between ears across the tested frequencies.

A simplified example

Consider a hypothetical set of hearing thresholds.

These numbers are invented solely to illustrate how audiograms display differences. They are not patient results, diagnostic thresholds, or a clinical example from a published study.

The example illustrates that hearing sensitivity can differ across frequencies and between ears.

A professional audiogram contains additional information, including test symbols, test methods, and sometimes results from bone-conduction and speech assessments.

Is there one universal numerical definition of asymmetric hearing loss?

No single numerical criterion is used in every clinical and research context.

Different studies and guidelines have used different frequency-specific thresholds to define clinically relevant asymmetry.

For example, a 2026 systematic review concerning imaging criteria for vestibular schwannoma found substantial variation among the audiometric definitions and screening methods used in published studies.

This illustrates why a difference measured on an audiogram should not be interpreted using one universal cutoff outside its clinical or research context.

Sources:

• ASHA — Hearing Loss in Adults
• Systematic Review of Audiological Screening Criteria, 2026

Conductive vs. Sensorineural Hearing Loss in One Ear

A hearing difference between ears can involve different types of hearing loss.

These terms describe which parts of the auditory system are affected.

A person can have unilateral conductive hearing loss, unilateral sensorineural hearing loss, or a mixed pattern.

Similarly, asymmetric hearing loss may involve different degrees or configurations of sensorineural, conductive, or mixed loss.

The fact that one ear hears differently from the other does not identify which hearing-loss type is present.

Source: ASHA — Hearing Loss in Adults

What Does Research Say About Asymmetric Hearing Loss and Vestibular Schwannoma?

Vestibular schwannoma is a benign tumor associated with the vestibulocochlear nerve.

It is among the less common conditions investigated in research involving asymmetric sensorineural hearing loss.

However, asymmetric hearing loss is considerably more common than vestibular schwannoma.

What did a 2026 systematic review find?

A review published in Neurosurgery in February 2026 examined the diagnostic yield of MRI investigations for vestibular schwannoma among people with selected hearing-related symptoms.

The systematic review identified 14 publications incorporating 13,733 patients.

After accounting for nonredundant datasets, the reported diagnostic yields were:

These figures refer to particular populations undergoing clinical evaluation, not to everyone who notices a hearing difference.

They should not be interpreted as individual probabilities.

The study's broader conclusion was that the diagnostic yield of imaging for vestibular schwannoma remained relatively low in these investigated populations.

What does this research establish?

It demonstrates that vestibular schwannoma is an uncommon finding even within certain clinically selected groups.

It does not establish the cause of any individual's hearing asymmetry.

The article also highlights that audiometric screening criteria are imperfect and continue to be evaluated in research.

Source: Strickland, Honaker & Olson (2026) — Congress of Neurological Surgeons Systematic Review

Is Gradual Hearing Loss Different From Sudden Hearing Loss?

Yes. Audiologists describe hearing loss not only by which ears are affected but also by how quickly it develops.

Gradual or progressive hearing loss develops or becomes more pronounced over time.

Sudden hearing loss involves a rapid change, sometimes occurring over hours or a few days.

According to the NIDCD, sudden sensorineural hearing loss frequently affects only one ear and is classified as a medical emergency.

Sudden hearing loss may also occur alongside tinnitus, dizziness, or a feeling of fullness in the ear.

That medical classification is separate from the general observation that some people have longstanding differences between their ears.

Source: NIDCD — Sudden Sensorineural Hearing Loss

How Do Researchers Study Unilateral Hearing Loss?

Researchers and audiologists use several types of assessments to understand differences between ears.

Pure-tone audiometry

Measures hearing sensitivity across sound frequencies and records the results separately for each ear.

Air- and bone-conduction measurements

Provide information about whether hearing loss involves conductive or sensorineural components.

Speech recognition testing

Examines how accurately spoken words can be recognized under controlled conditions.

Speech-in-noise testing

Measures speech understanding when competing noise is present.

Middle-ear assessment

Procedures such as tympanometry provide information about aspects of middle-ear function.

Sound localization research

Laboratory studies may use sounds presented from different positions to measure how accurately participants identify sound direction.

These methods answer different questions.

For example, a pure-tone audiogram describes hearing sensitivity but does not directly measure every aspect of real-world sound localization.

Sources:

• ASHA — Hearing Loss in Adults
• Sound Localization Review — American Journal of Audiology (2022)

What Hearing Technologies Are Discussed for Single-Sided Deafness?

Scientific and educational publications describe several hearing technologies used in connection with unilateral hearing loss and single-sided deafness.

They include:

Conventional hearing aids: Designed to amplify sounds when the affected ear has usable hearing.

CROS systems: Use microphones near the poorer-hearing ear to send sound to a device worn on the better-hearing side.

Bone-conduction systems: Transmit sound through vibrations to the functioning inner ear.

Cochlear implants: Provide electrical stimulation to the auditory nerve and have been studied in certain forms of single-sided deafness.

Each technology works differently.

For example, routing sound to the better-hearing ear is not equivalent to restoring normal hearing in both ears.

ASHA and Cambridge University Hospitals describe these approaches in their educational materials.

Their inclusion here explains the terminology found in hearing-health literature, not the suitability of any device for a particular individual.

Sources:

• ASHA — Unilateral Hearing Loss
• Cambridge University Hospitals — Single-Sided Deafness

Frequently Asked Questions About Hearing Loss in One Ear

Why does one ear hear better than the other?

Hearing sensitivity can differ between ears for several reasons, including earwax obstruction, middle-ear conditions, noise exposure, genetic factors, injuries, and conditions affecting the inner ear or auditory nerve. The hearing difference alone does not establish a specific cause.

Is it normal for ears to hear differently?

Small differences in hearing sensitivity can be recorded between ears. More substantial differences may be described as asymmetric hearing loss. The significance of a measured difference depends on its degree, frequency pattern, and other findings.

What is unilateral hearing loss?

Unilateral hearing loss means hearing loss affects one ear while the other ear has normal hearing, using ASHA's terminology.

Is asymmetric hearing loss the same as single-sided deafness?

No. Asymmetric hearing loss describes a difference between ears. Single-sided deafness generally refers to little or no functional hearing in one ear.

Can earwax cause hearing loss in one ear?

Yes. Earwax obstruction can interfere with sound transmission in one ear and is a recognized cause of conductive hearing loss.

Can noise exposure affect one ear more than the other?

Yes. Depending on exposure conditions, noise-related hearing damage may affect the ears differently.

Why is it harder to tell where sounds are coming from with one-sided hearing loss?

Sound localization uses timing and intensity differences between the ears. Unequal hearing can reduce access to these cues, making sound direction harder to identify.

Can someone with hearing loss in one ear hear conversations normally?

Some individuals can understand conversations well in quiet surroundings but experience more difficulty with background noise or when sounds arrive from the poorer-hearing side. Experiences vary.

Does asymmetric hearing loss mean someone has a tumor?

No. Research indicates that vestibular schwannoma is an uncommon finding in populations evaluated for asymmetric sensorineural hearing loss.

Is sudden hearing loss the same as gradual hearing loss?

No. These terms describe different rates of onset. The NIDCD classifies sudden sensorineural hearing loss as a medical emergency because it can develop rapidly and requires time-sensitive clinical evaluation.

Can both ears have hearing loss but one be worse?

Yes. This is one form of asymmetric hearing loss. The ears may differ in degree, configuration, or both.

What is the difference between hearing loss in the left ear and the right ear?

The terms describe which side is affected. The underlying type, degree, and cause of the hearing loss cannot be established from the side alone.

Final Thoughts: Hearing Doesn't Always Change Equally in Both Ears

Hearing differences between ears are a recognized part of audiology research and practice.

Unilateral hearing loss describes loss affecting one ear, while asymmetric hearing loss describes unequal hearing abilities between the ears.

These differences can affect everyday listening, including speech understanding in noise and identifying where sounds originate.

However, the hearing pattern alone does not establish an underlying cause.

Research continues to investigate how unequal hearing affects sound perception, how hearing asymmetry is defined, and how different auditory conditions can produce similar listening experiences.

Understanding the terminology makes it easier to interpret hearing-health information accurately, without confusing general research findings with individual diagnoses.

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Related article:

10 Early Signs of Hearing Loss in Adults (and What to Do Next)

Sources and References

1. American Speech-Language-Hearing Association (ASHA). Hearing Loss in Adults. Hearing-loss classifications, common causes, audiological testing, and hearing differences between ears.

2. ASHA. Unilateral Hearing Loss. Audiology Information Series, 2022. Definitions, possible causes, sound localization, speech understanding, and hearing technology terminology.

3. Cambridge University Hospitals NHS Foundation Trust. Single-Sided Deafness (Audiology). Explanation of head shadow, sound localization, speech in noise, and single-sided deafness.

4. National Library of Medicine / MedlinePlus. Earwax. Reviewed April 29, 2026. Earwax obstruction and conductive hearing loss.

5. MedlinePlus. Hearing Disorders and Deafness. Causes and general hearing-loss mechanisms.

6. American Journal of Audiology. Sound Localization of Listeners With Normal Hearing, Impaired Hearing, Hearing Aids, Bone-Anchored Hearing Instruments, and Cochlear Implants: A Review. 2022. Published research concerning sound localization and different hearing-loss patterns.

7. Strickland, B. A., Honaker, J. A., & Olson, J. R. (2026). Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines Update for the Role of Audiologic Screening in the Diagnosis and Management of Patients With Vestibular Schwannomas. Neurosurgery, 98(2), 278–282. DOI: 10.1227/neu.0000000000003426.

8. A Systematic Review of Audiological Criteria Used to Determine the Need for MRI Screening in Patients With Suspected Vestibular Schwannoma (2026). PubMed Research Record. Review of 20 studies examining audiometric screening criteria.

9. National Institute on Deafness and Other Communication Disorders (NIDCD). Sudden Sensorineural Hearing Loss. Distinction between sudden hearing loss and other patterns, with clinical classifications.

Editorial disclosure

This article was prepared using publicly available information from professional audiology organizations, government medical reference services, and peer-reviewed scientific research.

Audiology Digital did not conduct the studies discussed, independently collect clinical data, or perform original audiological evaluations.

The illustrative audiogram table contains fictional values for educational purposes only.

Research statistics are attributed to their original publications and are not presented as individual probabilities.

Medical information disclaimer

This content is provided solely for general education about hearing loss terminology and published research. It does not provide medical advice, assess individual symptoms, establish a diagnosis, recommend medical tests or treatment, or determine the significance of any individual's hearing differences.