What Causes Sensorineural Hearing Loss?

Sensorineural hearing loss can result from aging, loud noise, inherited conditions, certain medicines, infections, inner-ear disease, or head injury. The term describes damage to the inner ear or the nerve pathways carrying sound to the brain; it does not identify the cause by itself. ASHA explains the definition and main causes.

More than one factor can contribute. For example, someone may have both age-related hearing changes and damage from years of noise exposure. Sometimes no definite cause can be found.

If hearing drops suddenly, over hours or a few days, seek medical care immediately, today. Do not assume it is wax or congestion, even if the ear feels blocked. Delaying assessment and treatment can reduce treatment effectiveness, according to NIDCD’s sudden-deafness guidance. Our sudden sensorineural hearing loss guide covers that urgent-care decision.

Possible reasons for sensorineural hearing loss

Aging and accumulated exposure

Age-related hearing loss, called presbycusis, usually develops gradually in both ears. Changes in the inner ear and the nerve pathways involved in hearing can contribute. Long-term noise exposure, medical conditions, and genetic susceptibility may also play a role, so “age-related” does not necessarily mean aging is the only explanation.

High blood pressure and diabetes are associated with hearing loss, but having either condition does not establish why an individual’s hearing changed. NIDCD describes these overlapping factors.

Loud noise

Noise can damage the inner ear’s hair cells, the sensory cells that help turn sound vibrations into electrical signals. Human hair cells do not grow back after they die.

Damage may follow one intense event, such as an explosion, or repeated exposure to loud machinery, gunfire, concerts, or high-volume headphones. Both loudness and exposure time matter. Noise-related hearing loss can affect one or both ears and may become noticeable only gradually. NIDCD explains how noise damages hearing.

When discussing possible causes, include military, workplace, and recreational noise—not just your current environment. Reducing exposure and using appropriate hearing protection can help prevent further noise damage.

Genetic and early-life factors

Genetic hearing loss may be present at birth or develop later. A lack of known family history does not rule it out: many babies with genetic hearing loss have parents who hear normally but carry relevant gene changes. Hearing loss may occur alone or as part of a genetic syndrome. ASHA explains genetic hearing loss.

Being born with sensorineural hearing loss does not always mean the cause is genetic. Infections passed to a baby during pregnancy, including rubella or herpes, can also cause it. Problems with how the inner ear forms are another possible reason. MedlinePlus and ASHA describe these causes.

Medicines that can harm hearing

Some medicines are ototoxic, meaning they can harm hearing structures. These include certain treatments for severe infections, cancer, and heart disease—not every medicine in those categories. They may also cause tinnitus or balance problems.

Some medication-related hearing changes improve when treatment is changed or stopped; others are permanent. Do not stop a prescribed medicine on your own. Ask the prescriber about the drug’s hearing risks, whether hearing monitoring is appropriate, and whether an alternative is available. ASHA’s medication guidance explains the risks and the importance of discussing them with your doctor.

Infections and inner-ear disease

Infections such as meningitis, mumps, and measles can cause sensorineural hearing loss. Immune disease and blood-vessel disease are also recognized causes. MedlinePlus lists these medical causes.

Two inner-ear conditions deserve distinction:

• Autoimmune inner-ear disease: the immune system attacks the body’s own tissues and can cause rapidly developing hearing loss. ASHA describes this condition.
• Ménière’s disease: an inner-ear disorder associated with hearing loss that can fluctuate, vertigo, tinnitus, and fullness. Its symptoms are linked to an inner-ear fluid imbalance, but the underlying cause remains unclear. These symptoms alone do not establish the diagnosis. NIDCD explains Ménière’s disease.

Injury or a tumor affecting hearing

Head or ear injuries can damage hearing structures. MedlinePlus includes injury among SNHL causes.

An acoustic neuroma, also called a vestibular schwannoma, is another possible cause. This noncancerous tumor usually grows on the balance portion of the nerve responsible for hearing and balance. It can cause sudden or gradual sensorineural hearing loss. Boston Medical Center explains this tumor. These possibilities require medical evaluation rather than an assumption based on symptoms alone.

How clinicians investigate the reason

An audiologist identifies and measures the hearing loss; an ear, nose and throat specialist can investigate an underlying medical cause. NIDCD describes their different roles.

Bring a short history to the appointment:

• When you first noticed the change and whether it was gradual, sudden, or fluctuating.
• Whether one ear or both ears are affected.
• Noise exposure, including blasts, firearms, machinery, and loud music.
• Current and past medicines, major infections, and head injuries.
• Family hearing history and any accompanying tinnitus or dizziness.

Earwax blockage and middle-ear fluid usually cause conductive hearing loss, not sensorineural loss, although both types can coexist. ASHA explains these types of hearing loss; our sensorineural versus conductive hearing loss guide covers the distinction in more detail.

A cause may remain uncertain even after evaluation. This is particularly common with sudden sensorineural hearing loss: NIDCD reports an identifiable cause in only about 10% of diagnosed cases. That uncertainty does not remove the need for assessment or care. NIDCD explains what is known about sudden-loss causes.