Hearing loss is defined as one of three types:

• Conductive (involves outer or middle ear)
• Sensorineural (involves inner ear)
• Mixed (combination of the two)

Aging and chronic exposure to loud noises both contribute to hearing loss. Other factors, such as excessive earwax, can temporarily reduce how well your ears conduct sounds.

You can't reverse most types of hearing loss. However, you and your doctor or a hearing specialist can take steps to improve what you hear.

Symptoms

Signs and symptoms of hearing loss may include:

• Muffling of speech and other sounds
• Difficulty understanding words, especially against background noise or in a crowd
• Trouble hearing consonants
• Frequently asking others to speak more slowly, clearly and loudly
• Needing to turn up the volume of the television or radio
• Withdrawal from conversations
• Avoidance of some social settings

Causes

To understand how hearing loss occurs, it can be helpful to first understand how you hear.

How you hear

Your ear consists of three major areas: outer ear, middle ear and inner ear. Sound waves pass through the outer ear and cause vibrations at the eardrum. The eardrum and three small bones of the middle ear amplify the vibrations as they travel to the inner ear. There, the vibrations pass through fluid in a snail-shaped structure in the inner ear (cochlea).

Attached to nerve cells in the cochlea are thousands of tiny hairs that help translate sound vibrations into electrical signals that are transmitted to your brain. Your brain turns these signals into sound.

How hearing loss can occur

Causes of hearing loss include:

• Damage to the inner ear. Aging and exposure to loud noise may cause wear and tear on the hairs or nerve cells in the cochlea that send sound signals to the brain. When these hairs or nerve cells are damaged or missing, electrical signals aren't transmitted as efficiently, and hearing loss occurs. Higher pitched tones may become muffled to you. It may become difficult for you to pick out words against background noise.
• Gradual buildup of earwax. Earwax can block the ear canal and prevent conduction of sound waves. Earwax removal can help restore your hearing.
• Ear infection and abnormal bone growths or tumors. In the outer or middle ear, any of these can cause hearing loss.
• Ruptured eardrum (tympanic membrane perforation). Loud blasts of noise, sudden changes in pressure, poking your eardrum with an object and infection can cause your eardrum to rupture and affect your hearing.