What are the two basic types of hearing loss?
There are two basic types of hearing loss:
Hearing loss that involves the ability of the ear to conduct sound waves through the ear to the auditory nerve. This type of hearing loss is called "conductive" hearing loss. It can result from damage to the ear drum or the bones in the middle ear (malleus, incus, stapes).
Causes of conductive hearing loss:
- a build-up of ear wax
- a decrease in the free movement of the small bones in the middle ear (e.g. as a result of fluid build up or stickiness of the small bones in the middle ear)
- an inner ear infection (otitis media)
- a perforated ear drum
- damage to the eardrum or middle ear from sudden pressure changes
Hearing loss that involves the transmission of sound to the brain along the auditory nerve is called "sensorineural" hearing loss. In the case of sensorineural hearing loss, sound waves are conducted by the eardrum and the bones of the middle ear, but they aren't "heard" because they are not transmitted to the brain by the auditory nerve.
Causes of sensorineural hearing loss:
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a genetic condition
- injury during birth or prematurity
- damage to the fetus during pregnancy (e.g. as a result of rubella - German measles)
- severe jaundice after birth
- a build-up of fluid in the inner ear (Meniere's disease)
- damage to the structures of the inner ear (cochlea, saccule, utricle and semicircular canals) from prolonged exposure to loud noise
- damage to the structures of the inner ear and the auditory nerve from certain medications (e.g. antibiotics such as streptomycin and gentamycin)
- the natural degeneration of the structures in the inner ear and the auditory nerve due to age
- damage to the auditory nerve (possibly as a result of a tumor or an injury)
- head injury

What are some ways I can protect my hearing?
Sound: Whisper
- Decibels (unit of sound): 30 dB
- *Risk: None
Sound: Normal Speech
- Decibels (unit of sound): 50-55 dB
- *Risk: none
Sound: Vacuum Cleaner
- Decibels (unit of sound): 70 dB
- *Risk: none
Sound: City Traffic
- Decibels (unit of sound): 80 dB
- *Risk: just under the hazardous level
85 dB hazardous if exposure is prolonged for over 8 hours.
Sound: Lawn Mower
- Decibels (unit of sound): 90 dB
- *Risk: hazardous if exposure is prolonged
Sound: rock concert, nearby jet plane, chain saw, pneumatic drill
- Decibels (unit of sound): average 95 dB
- *Risk: hazardous if exposure is prolonged
110 dB danger limit - even 5 minutes of steady exposure can lead to some hearing loss. 170 dB sound can literally blow you off your feet.
- Reporting ear problems to your doctor without delay. Symptoms of an ear problem may include: earache, discharge from the ears, feeling like your ears are always plugged, hearing loss, hearing unusual sounds (such as ringing or buzzing), dizziness, imbalance or redness or swelling in the ear.
What are some signs of hearing loss?
- Sounds generally seem quieter than before.
- You tend to favour listening with one ear over the other.
- Sound may be distorted or unclear.
- You often think that other people are mumbling or not speaking clearly.
- You ask others to "speak up" often.
- You have trouble hearing certain people, but not others (people with high-pitched voices are often harder to hear in early stages of hearing loss. Lower tones may not be heard as hearing loss progresses.)
- The consonants "s", "f", and "z" are hard to make out.
- You find it more of an effort to take part in activities that require listening than you used to (e.g. listening to music, watching movies, engaging in conversation).
- You have trouble following conversations, especially if there is noise in the background.
- You experience hissing, buzzing, ringing noises or a full feeling in your ears after being exposed to loud noises.
- You hear better when you can see the face of a person who is speaking.
- You often have to guess what people are saying to you.
- You often ask people to repeat themselves.
- People accuse you of not listening.
- You have needed to increase the volume on your radio, stereo or television.
- You prefer to listen to music, radio, etc. with ear phones.
- You are often startled by people who approach you quietly, or from the side or behind you.
How do you treat or prevent hearing loss?
-
The treatment of hearing loss depends very much on the cause of the hearing loss and the extent of damage. If you suspect that you are losing your ability to hear well, discuss the matter with your doctor so that hearing tests can be arranged, a proper diagnosis can be made and the appropriate treatment plan established.
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Hearing loss that results from a build-up of ear wax can be treated very effectively by having a doctor or other healthcare professional spray warm water into the ear canal with a syringe. Further build up of ear wax can be prevented by:
- not sticking things like fingers and cotton-tipped swabs in your ears, as these can push the wax in further and compact it against the ear drum (making it harder).
- gently rinsing the ears with water as part of your daily bath or shower.
- A perforation of the ear drum will generally heal on its own. If a perforated ear drum has not healed in 2-3 months, a minor surgical procedure (tympanoplasty) may be needed to repair the ear drum.
- An infection involving the middle ear is generally treated with antibiotics. Symptoms of earache, ear itching, dizziness, fever, headache and runny nose should be reported to a doctor.
- If there is a build up of fluid in the middle ear, a minor surgery, which involves making a small opening and inserting a tube in the ear drum, can be done to allow the fluid to drain out from behind the ear drum.
- In cases where the small bones of the middle ear do not move easily, an artificial bone can sometimes be surgically implanted.
- Tumors on the auditory nerve must be removed surgically to prevent or minimize nerve damage and preserve hearing.
- Extensive damage to the auditory nerve may result in permanent hearing loss.
- Hearing aids can be of great benefit to some people with hearing loss, but they are not effective for everyone. Some hearing aids work by creating vibrations that are transmitted to the inner ear through contact with the bone behind the ear. Others work by amplifying sound waves (making them louder). Be sure to discuss your choice of hearing aid with your doctor to ensure that it is a type that will work well for your type of hearing loss.
References
* The Complete Canadian Health Guide, June Engel, Ph.D., Editor, University of Toronto - Faculty of Medicine, Key - Porter Books, Toronto, 1993.
Review Date : January 2004
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