Hearing Loss in One Ear

Unilateral hearing loss, asymmetric hearing loss and single-sided deafness

These terms are related but do not mean exactly the same thing.

- Unilateral hearing loss: Hearing loss affects one ear. - Asymmetric hearing loss: Both ears may have hearing loss, but one ear is significantly poorer than the other. - Single-sided deafness: One ear has severe-to-profound hearing loss or no usable hearing, while the other ear has normal or better hearing.

An audiologist uses a comprehensive evaluation to describe the degree, type and pattern in each ear. The results help determine whether additional medical assessment is needed and which management options are realistic.

Signs of hearing loss in one ear

One-sided hearing loss may be less obvious than hearing loss in both ears because the better ear compensates in quiet settings.

Common signs include:

- Turning one ear toward a speaker - Hearing better when the speaker sits on a particular side - Difficulty following conversation in restaurants or groups - Trouble identifying where a voice, phone or alarm is located - Missing speech from the affected side - Frequently changing ears during telephone calls - Feeling that one ear is blocked, dull or different - Tinnitus in one ear - Dizziness or imbalance - Greater listening fatigue

You may perform well in a quiet one-to-one conversation but struggle when sound comes from different directions.

Why two ears matter

The brain combines input from both ears to organize the sound environment.

### Locating sound

Small differences in timing and loudness between the ears help the brain estimate where sound originates. When one ear provides reduced or unusable information, locating traffic, alarms, voices or a ringing phone becomes more difficult.

### Understanding speech in noise

Two ears help the brain separate speech from competing sound. With unilateral hearing loss, understanding often depends strongly on where the speaker and noise are located.

### Hearing around the head

The head naturally blocks some high-frequency sound before it reaches the ear on the opposite side. This is called the head-shadow effect. If the better ear faces away from a speaker, important speech details may be reduced.

### Listening effort

The better ear may detect sound, but the brain has less information to work with. Meetings, classrooms and social events can therefore require more concentration and produce fatigue.

What causes hearing loss in one ear?

Possible causes range from temporary sound blockage to inner-ear or nerve conditions. Symptoms alone cannot identify the cause.

### Outer- or middle-ear causes

Conductive hearing loss occurs when sound does not travel efficiently through the outer or middle ear. Possible causes include:

- Earwax blockage - Fluid behind the eardrum - Ear infection - Eardrum injury - Changes involving the middle-ear bones - Differences in ear-canal or ear structure

Some conductive conditions are medically treatable. An ear examination and hearing tests are needed to determine the pattern.

### Inner-ear or auditory-nerve causes

Sensorineural hearing loss involves the cochlea or auditory nerve. Possible associations include:

- Sudden sensorineural hearing loss - Noise or acoustic trauma - Head injury - Viral or other illness - Certain medications - Inner-ear disorders - Genetic or congenital factors - Vestibular schwannoma or another uncommon condition affecting the hearing nerve

In many cases, a definite cause is not found. A lack of obvious explanation is not a reason to skip evaluation.

### Mixed hearing loss

Mixed hearing loss combines conductive and sensorineural components. Care may involve medical treatment, hearing technology or both.

When is one-sided hearing loss urgent?

Seek immediate medical evaluation when hearing drops suddenly or changes rapidly over hours or a few days. Do not wait to see whether it clears and do not rely on an online hearing test.

Sudden sensorineural hearing loss may occur with:

- Ear fullness or pressure - Tinnitus - Dizziness or vertigo - A sudden “pop” - Hearing loss noticed upon waking

It can be mistaken for earwax, allergies or congestion. Treatment may be time-sensitive.

Call emergency services if sudden hearing change occurs with facial drooping, weakness, numbness, difficulty speaking, loss of coordination, fainting, severe headache or other possible stroke symptoms.

Why gradual or longstanding asymmetry still needs evaluation

Not every one-sided difference is an emergency, but persistent unilateral or asymmetric hearing loss should be professionally assessed.

Most people with one-sided hearing loss do not have a tumor. However, NIDCD notes that unilateral or asymmetric hearing loss, one-sided tinnitus and balance symptoms can be early signs of a vestibular schwannoma—a usually benign growth affecting hearing and balance nerves.

Because these symptoms also occur with many more common ear conditions, testing is used to decide whether imaging or specialist evaluation is appropriate. Do not assume that every asymmetric result requires an MRI, and do not assume that asymmetry is harmless.

How hearing loss in one ear is evaluated

The evaluation usually begins with an audiologist and may also involve an ENT.

### Health and hearing history

The clinician will ask about:

- When the difference began - Whether it was sudden, gradual or fluctuating - Ear pain, drainage, fullness or previous infections - Tinnitus - Dizziness or balance problems - Noise exposure - Head or ear injury - Medications and relevant health conditions - Previous hearing results

### Ear examination

The ear canal and eardrum are examined for wax, infection, structural changes or other visible findings.

### Comprehensive hearing evaluation

Testing may include:

- Air- and bone-conduction thresholds - Speech-recognition testing for each ear - Middle-ear testing - Otoacoustic emissions - Other tests selected for the symptoms

Testing each ear separately is essential. A screening that combines responses from both ears may miss an important difference.

### Medical and imaging evaluation

An ENT may review the hearing pattern, examine the ears and decide whether medical treatment, laboratory work, balance testing or imaging is appropriate. MRI is commonly used when evaluation for a vestibular schwannoma or another hearing-nerve condition is indicated.

The decision should be individualized rather than based on an online checklist.

Treatment and management options

The best option depends on the cause, degree of loss, hearing in the better ear, communication needs, anatomy, health history and personal preference.

### Treating an underlying medical cause

Wax, infection, fluid, eardrum problems or other medical conditions may need treatment by a physician or another qualified professional. Sudden sensorineural hearing loss requires immediate medical management.

Correcting the underlying condition may improve hearing in some cases, but outcomes vary.

### A conventional hearing aid

When the affected ear has usable hearing, a hearing aid may improve access to speech and environmental sound. Careful fitting and verification help determine whether amplification is providing meaningful benefit.

A trial and follow-up are important because word recognition and comfort can differ even among people with similar audiograms.

### CROS and BiCROS systems

A CROS system places a microphone on the poorer ear and sends sound to a device worn on the better ear. It can improve awareness of sound arriving from the affected side.

A BiCROS system works similarly but also amplifies sound for a better ear that has its own hearing loss.

These systems do not restore hearing in the poorer ear and usually do not restore normal sound localization. Their value depends on listening situations and individual goals.

### Bone-conduction devices

Bone-conduction systems send sound through vibration of the skull. Some are worn externally, while others involve an implanted component.

For conductive or mixed unilateral loss, bone-conduction technology may deliver sound to a functioning inner ear. For single-sided deafness, it may route sound from the poorer side to the better-hearing inner ear.

A nonsurgical trial may help demonstrate likely benefit before an implanted option is considered. Surgery requires evaluation by an appropriate medical team.

### Cochlear implants

A cochlear implant may be considered for selected adults or children with single-sided deafness or severe asymmetric hearing loss when conventional amplification does not provide adequate benefit.

Unlike routing systems, a cochlear implant provides input to the auditory pathway on the affected side. Potential benefit can include improved access to speech, localization or tinnitus relief for some candidates, but outcomes vary.

Candidacy depends on hearing results, speech understanding, duration of loss, anatomy, health considerations and current device indications. Evaluation requires a specialized audiologist and implant physician.

### Remote microphones and assistive technology

A remote microphone placed near the speaker sends the voice directly to a receiver, hearing aid or implant processor. It can improve the speech-to-noise ratio in meetings, classrooms, cars or restaurants.

Other tools include captioning, alerting devices and telephone accessibility features.

### Communication strategies

Practical positioning can make a large difference:

- Place the better ear toward the speaker - Ask speakers to face you - Reduce background noise when possible - Choose seating with a wall behind you - Move closer to the person speaking - Use captions for calls and media - Ask for key information in writing - Tell others which side is easier for you

Strategies support communication whether or not technology is used.

Protecting the better-hearing ear

When one ear carries most usable hearing, protecting it becomes especially important.

- Use appropriate protection around hazardous noise - Lower personal-listening volume - Move away from intense sound when possible - Review potentially ototoxic medication concerns with the prescribing clinician - Schedule monitoring at the interval recommended by the audiologist - Seek prompt care for any new change in the better ear

Do not overprotect the ear in ordinary safe environments; unnecessary constant earplug use can interfere with communication. An audiologist can help select protection appropriate for specific activities.

Hearing loss in one ear in children

Children with unilateral hearing loss may hear well in quiet but struggle in classrooms, group activities and situations where the teacher is on the poorer side. Difficulty locating sound and increased listening effort can affect learning, behavior or social participation.

Management may include:

- Regular audiologic monitoring - Classroom seating and acoustic changes - Remote-microphone technology - Hearing aids, routing systems or implant evaluation when appropriate - Speech-language, educational or developmental support - A school accommodation plan

One normal-hearing ear does not eliminate the need for follow-up.

Questions to ask your audiologist

- Is the hearing loss unilateral or asymmetric? - Is it conductive, sensorineural or mixed? - Does the pattern require medical referral? - Is the affected ear likely to benefit from amplification? - What are the realistic benefits and limits of each device option? - Can I trial a nonsurgical technology first? - Would a remote microphone help in my most difficult situations? - How should I protect and monitor the better ear? - When should I repeat testing?

The bottom line

Hearing loss in one ear can affect speech understanding, sound localization, safety awareness and listening effort even when the other ear hears normally.

Sudden one-sided hearing loss is a medical emergency. Gradual or longstanding asymmetry is less urgent but still deserves a comprehensive hearing evaluation and, when indicated, ENT assessment.

Management may include treatment of an underlying condition, a conventional hearing aid, CROS or BiCROS technology, bone-conduction devices, a cochlear implant, assistive technology or communication strategies.

Use the Audiology.md provider directory to find an audiologist experienced in unilateral hearing loss.

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Medical disclaimer: This article provides general education and does not diagnose or treat any person. Sudden hearing loss requires immediate professional medical evaluation. Call emergency services for possible stroke or other emergency symptoms.

Explore hearing care

Frequently asked questions

Sources

• Unilateral hearing loss
• Sudden sensorineural hearing loss
• Vestibular schwannoma
• Tinnitus
• Cochlear implants
• Sudden sensorineural hearing loss FAQs
• Tinnitus