Sensorineural hearing loss (SNHL) is caused by damage to the structures in your inner ear or your auditory nerve. It is the cause of more than 90 percentof hearing loss in adults. Common causes of SNHL include exposure to loud noises, genetic factors, or the natural aging process.

A spiraling organ inside your inner ear called your cochlea contains tiny hairs known as stereocilia. These hairs convert vibrations from sound waves into neural signals that your auditory nerve carries to your brain. Exposure to sounds louder than 85 decibels can damage these hairs.

However, you might not experience hearing loss until 30 to 50 percent of these hairs are damaged. Eighty-five decibels is roughly equivalent to heavy traffic noise heard from inside a car.

SNHL can range from mild hearing loss to complete hearing loss depending on the degree of damage.

  • Mild hearing loss. A loss of hearing between 26 to 40 decibels.
  • Moderate hearing loss. A loss of hearing between 41 to 55 decibels.
  • Severe hearing loss. A loss of hearing more than 71 decibels.

SNHL isn’t a life threatening condition, but it can interfere with your ability to communicate if not properly managed. Keep reading to find out what causes SNHL, how you can prevent it, and your treatment options if you’re currently dealing with it.

SNHL can occur in one ear or both ears depending on the cause. If your SNHL onsets gradually, your symptoms might not be obvious without a hearing test. If you experience sudden SNHL, your symptoms will come on within several days. Many people first notice sudden SNHL upon waking.

Sensorineural hearing loss can lead to:

  • trouble hearing sounds when there’s background noise
  • particular difficulty understanding children’s and female voices
  • dizziness or balance problems
  • trouble hearing high-pitched sounds
  • sounds and voices seem muffled
  • feeling like you can hear voices but can’t understand them
  • tinnitus (ringing in your ears)

SNHL can be congenital, meaning that it is present a birth, or acquired. The following are potential causes of SNHL.

Congenital

Congenital hearing loss is present from birth and is one of the most common birth abnormalities. It affects about 1 to 3 babies per 1,000 births.

About 50 percent of children born with congenital hearing loss develop it from genetic factors and the other half develop it from environmental factors. More than 100 genes have been linked to genetic hearing loss. Infections and a lack of oxygen can all lead to hearing loss.

Loud noises

Exposure to sounds over about 85 decibels can lead to SNHL. Even one-time exposure to sounds like gunshots or explosions can cause permanent hearing damage.

Presbycusis

Presbycusis is another name for age-related hearing loss. About 1 in 3 people between the ages of 65 and 74 in the United States have hearing loss. By the age of 75, about half have some type of hearing loss.

Damage to your auditory nerve or the structures of your inner ear can lead to SNHL. This type of hearing loss leads to problems converting sound vibrations to neural signals that the brain can interpret.

Conductive hearing loss occurs when sound can’t pass through your outer or middle ear. The following can cause conductive hearing loss.

  • fluid buildup
  • ear infections
  • hole in your eardrum
  • benign tumors
  • earwax
  • obstruction by foreign objects
  • deformations in the outer or middle ear

Both types of hearing loss can cause similar symptoms. However, people with conductive hearing loss often hear muffled sounds while people with SNHL hear muffled and distorted sounds.

Some people experience a mix of both sensorineural and conductive hearing loss. Hearing loss is considered mixed if there are problems both before and after the cochlea.

It’s important to get a proper diagnosis if you’re dealing with hearing loss. In some cases, it’s possible to regain your hearing. The quicker you receive treatment, the more likely you are to minimize damage to the structures of your ear.

SSHL is a hearing loss of at least 30 decibels within 3 days. It affects roughly 5 to 20 in 100,000 people and usually only affects one ear. SSHL leads to deafness either instantly or over a few days. It often only affects one ear and many people first notice it after waking in the morning.

Medical Emergency

SSHL may have a serious underlying cause. If you experience sudden deafness you should see a doctor as soon as possible.

The following causes can all lead to sudden deafness.

The most common treatment option for sudden hearing loss is the prescription of corticosteroids. Taking corticosteroids within 2 weeks of the onset of SSHL gives you the best chance of regaining your hearing.

Sensorineural hearing loss may affect one ear or both ears depending on the cause.

  • Bilateral sensorineural hearing loss. Genetics, exposure to loud sounds, and diseases like measles can lead to SNHL in both ears.
  • Unilateral sensorineural hearing loss. SNHL might only affect one ear if it’s caused by a tumor, Meniere’s disease, or a sudden loud noise in one ear.
  • Asymmetrical sensorineural hearing loss. Asymmetrical SNHL occurs when there’s hearing loss on both sides but one side is worse than the other.

Doctors use several types of tests to properly diagnose sensorineural hearing loss.

Physical exam

A physical exam can help differentiate SNHL from conductive hearing loss. A doctor will search for inflammation, fluid or earwax buildup, damage to your eardrum, and foreign bodies.

Tuning forks

A doctor may use a tuning fork test as an initial screening. Specific tests include:

  • Weber’s test. The doctor strikes a 512 Hz tuning fork softly and places it near the midline of your forehead. If the sound is louder in your affected ear, hearing loss is likely conductive. If sound is louder in your unaffected ear, hearing loss is likely sensorineural.
  • Rinne test. The doctor strikes a tuning fork and places it against your mastoid bone behind your ear until you no longer hear the sound. Your doctor then moves the tuning fork in front of your ear canal until you can’t hear the sound. If you have SNHL, you’ll be able to hear the tuning fork better in front of your ear canal than against your bone.

Audiogram

If a doctor expects you have hearing loss, they will likely send you for a more accurate audiometer test performed by an audiologist.

During the test, you’ll wear headphones in a soundproof booth. Tones and words will be played into each ear at different volumes and frequencies. The test helps find the quietest sound that you can hear and specific frequencies of hearing loss.

Right now, there’s no surgical option to treat SNHL. The most common options are hearing aids and cochlear implants to help you compensate for hearing loss. Gene therapy for hearing loss is an expanding field of research. However, at this time it’s not clinically used for SNHL.

Hearing aids

Modern hearing aids can match specific hearing loss symptoms. For example, if you have problems hearing high-frequency sounds, a hearing aid can help dial in these sounds without affecting other frequencies.

Cochlear implants

A cochlear implant is a device that can be surgically implemented to help with severe SNHL. A cochlear implant has two parts, a microphone you wear behind your ear and a receiver inside your ear that sends electrical information to your auditory nerve.

The outlook for people with SNHL is highly variable depending on the extent and cause of hearing loss. SNHL is the most common type of permanent hearing loss.

In cases of sudden SSHL, the Hearing Loss Association of America says that 85 percent of people will experience at least a partial recovery if they’re treated by an ear, nose, and throat doctor. About 32 to 65 percent of people regain their hearing spontaneously within 2 weeks.

Does sensorineural hearing loss get worse?

SNHL often progresses over time if it’s caused by age-related or genetic factors. If it’s caused by a sudden loud noise or environmental factors, symptoms will likely plateau if you avoid the cause of hearing damage.

SNHL is a natural part of the aging process for many people. However, exposure to loud noises can also cause permanent damage to your inner ear or auditory nerve. Following these healthy hearing habits can help you avoid noise-related ear damage:

  • Keep your headphone volume under 60 percent.
  • Wear earplugs around loud noises.
  • Consult a doctor before starting a new medication.
  • Get regular hearing tests.