Hearing Loss
Definition
Hearing loss : full or partial decrease in the ability to detect or understand sounds.
Types
Conductive deafness
Sensorineural hearing loss
Causes
Long-term exposure to environmental noise
Genetic
Disease or illness
Medications
Physical trauma
Disease or illness :
Measles - auditory nerve damage
Meningitis
Autoimmune disease - cochlear damage.
Mumps - sensorineural hearing loss
Presbycusis - impairment accompanying age - affecting sensitivity to higher frequencies
Adenoids - may obstruct the Eustachian tube, causing conductive hearing impairment and nasal infections that can spread to the middle ear.
AIDS - auditory system anomalies.
Chlamydia may cause hearing loss in newborns.
Fetal alcohol syndrome - infants born to alcoholic mothers - effect on the developing fetus
Premature birth results in sensorineural hearing loss
Syphilis transmitted to the new born - hearing loss
Otosclerosis
Superior canal dehiscence, a gap in the bone cover above the inner ear, can lead to low-frequency conductive hearing loss, autophony and vertigo
Categories of hearing impairment
Hearing sensitivity - quietest sound that an individual can detect, called the hearing threshold. measured by a behavioral audiogram
Speech discrimination impairment - sound is detected but not understood
Conductive hearing - sound is not normally conducted through the outer or middle ear or both. - hearing loss is often only mild - Hearing thresholds will not rise above 55-60 dB from outer or middle ear problems alone. - quality of hearing (speech discrimination) is good, as long as the sound is amplified loud enough to be easily heard.
Sensorineural hearing loss
A sensorineural hearing loss is due to insensitivity of the inner ear, the cochlea, or to impairment of function in the auditory nervous system:
Abnormalities in the hair cells of the organ of Corti in the cochlea.
Impairment of the VIIIth cranial nerve, the Vestibulocochlear nerve or the auditory portions of the brain
Quantification of hearing loss
The severity of hearing loss is measured in decibels
Mild:
for adults: between 25 and 40 dB
for children: between 20 and 40 dB
Moderate: between 41 and 55 dB
Moderately severe: between 56 and 70 dB
Severe: between 71 and 90 dB
Profound: 90 dB or greater
Pre-lingual deafness
Prelingual hearing impairment exists when the impairment is congenital or otherwise acquired before the individual has acquired speech and language.
Post-lingual hearing impairment
Post-lingual hearing impairment where hearing loss is adventitious after the acquisition of speech and language, usually after the age of six. It may develop due to disease, trauma, or as a side-effect of a medicine. Typically, hearing loss is gradual and often detected by family and friends of the people so affected long before the patients themselves will acknowledge the disability. Common treatments include hearing aids and learning lip reading. Loneliness and depression can arise as a result of isolation (from the inability to communicate with friends and loved ones) and difficulty in accepting their disability.[citation needed]
Medical treatments
Approaches
Hearing aids
Cochlear implants
Gene therapy
Research in progress
Adaptations to hearing impairment
telecommunications devices for the deaf (TDD).
textphone
minicom.
Wireless, internet and mobile phone/SMS text messaging are beginning to take over the role of the TDD.
flashing lights to signal events such as a ringing telephone, a doorbell, or a fire alarm.
Video conferencing
TTY or computer keyboard
3.4 Hard-of-hearing
3.5 Unilateral hearing loss
4 Social impact
4.1 Pre-lingual impairment
4.2 Post-lingual impairment
5 Medical treatments
5.1 Approaches
5.2 Views of treatments
5.3 Gene therapy
6 Adaptations to hearing impairment
7 Resources
8 Bibliography
9 References
10 See also
11 Quotations
12 External links
