Hearing loss

• Muffled quality of speech and other sounds
• Difficulty understanding words, especially against background noise or in a crowd of people
• 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

How you hear

Hearing occurs when sound waves reach the structures inside your ear, where the sound wave vibrations are converted into nerve signals that your brain recognizes as sound.

Your ear consists of three major areas: the 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 — the hammer, anvil and stirrup — amplify the vibrations as they travel to the inner ear. There, the vibrations pass through fluid in the cochlea, a snail-shaped structure in the inner ear.

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. The vibrations of different sounds affect these tiny hairs in different ways, causing the nerve cells to send different signals to your brain. That's how you distinguish one sound from another.

What causes hearing loss

For some people, the cause of hearing loss is the result of a gradual buildup of earwax, which blocks the ear canal and prevents conduction of sound waves. Earwax blockage is a cause of hearing loss among people of all ages.

In most cases, however, hearing loss results from damage to the inner ear. Aging and prolonged 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. Heredity may make you more prone to these changes.

Ear infection and abnormal bone growths or tumors of the outer or middle ear can cause hearing loss. A ruptured eardrum also may result in loss of hearing. 

Risk factors

Factors that may damage or lead to loss of the hairs and nerve cells in your inner ear include:

• Aging. Exposure to sounds over the years can damage the cells of your inner ear.
• Heredity. Your genetic makeup may make you more susceptible to ear damage.
• Occupational noises. Jobs where loud noise is a regular part of the working environment, such as farming, construction or factory work, can lead to damage inside your ear.
• Recreational noises. Exposure to explosive noises, such as from firearms and fireworks, can cause immediate, permanent hearing loss. Other recreational activities with dangerously high noise levels include snowmobiling, motorcycling or listening to loud music. Personal music players such as MP3 players can cause lasting hearing loss if you turn the volume up high enough to mask the sound of other loud noises, such as a lawn mower.
• Some medications. Drugs such as the antibiotic gentamicin and certain chemotherapy drugs can damage the inner ear. Temporary effects on your hearing — ringing in the ear (tinnitus) or hearing loss — can occur if you take very high doses of aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs), antimalarial drugs or loop diuretics.
• Some illnesses. Diseases or illnesses that result in high fever, such as meningitis, may damage the cochlea.

Complications

Hearing loss can have a significant effect on your quality of life. Among older adults with hearing loss, commonly reported problems include:

• Depression
• Anxiety
• An often false sense that others are angry with you

Unfortunately, most people affected by hearing loss live with these difficulties for years before seeking treatment — or never seek treatment at all. This may cause lasting problems for those who love you, as well, if you try to cope by denying your hearing loss or withdrawing from social interactions.

Getting treatment can dramatically improve your quality of life. People who use hearing aids report the following benefits:

• Greater self-confidence
• Closer relationships with loved ones
• Improved outlook on life, overall

Family and friends of people who have begun using a hearing aid are even more likely to report these improvements in shared quality of life.

Diagnosis

Tests to diagnose hearing loss may include:

• General screening tests. Your doctor may ask you to cover one ear at a time to see how well you hear words spoken at various volumes and how you respond to other sounds.
• Tuning fork tests. Tuning forks are two-pronged, metal instruments that produce sounds when struck. Simple tests with tuning forks can help your doctor detect hearing loss. A tuning fork evaluation may also reveal whether hearing loss is caused by damage to the vibrating parts of your middle ear (including your eardrum), damage to sensors or nerves of your inner ear, or damage to both.
• Audiometer tests. During these more-thorough tests conducted by an audiologist, you wear earphones and hear sounds directed to one ear at a time. The audiologist presents a range of sounds of various tones and asks you to indicate each time you hear the sound. Each tone is repeated at faint levels to find out when you can barely hear. The audiologist will also present various words to determine your hearing ability.

References:

http://nihseniorhealth.gov/hearingloss/toc.html

http://www.asha.org/public/hearing/Types-of-Hearing-Loss/

https://en.wikipedia.org/wiki/Hearing_loss

http://www.hearinglossireland.ie

http://www.emedicinehealth.com/hearing_loss/article_em.htm