Hearing impairment

A hearing impairment is a decrease in one's ability to hear (i.e. perceive auditory information). While some cases of hearing loss are reversible with medical treatment, many lead to a permanent disability (often called deafness).

Categories of hearing impairment

Hearing loss is catagorized by its severity and by the age of onset. Two persons with the same severity of hearing loss will experience it quite differntly if it occurs early or late in life. Furthermore, a loss can occur on only one side (unilateral) or on both (bilateral).

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Types

There are three major types of hearing loss: neural/sensorineural, conductive, or a combination of both. Treatment depends upon the type of hearing loss that is present.

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Sensorineural

Sensorineural hearing loss is caused by damage/malfunction of the inner ear (cochlea, eighth cranial nerve) or auditory brainstem. This can be divided further into a sensory hearing loss (inner ear) or a neural hearing loss (brainstem).

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Conductive

Conductive hearing loss is caused by damage/malfunction of the middle or outer ear system (external ear canal, ear drum, or structures in the middle ear space including the malleus, incus and stapes bones).

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Combination

Mixed hearing loss is caused by both conductive and sensorineural causes.

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Quantification of hearing loss

The severity of hearing loss is measured by the degree of loudness, as measured in decibels, a sound must attain before being detected by an individual. Hearing loss may be ranked as mild, moderate, severe or profound. It is quite common for someone to have more than one degree of hearing loss (i.e. mild sloping to severe). The following list shows the rankings and their corresponding decibel ranges:

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• Mild:
• for adults: between 25 and 40 dB
• for children: between 15 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- or postlingual

The age at which the hearing impairment develops is crucial to spoken language acquisition. Post-lingual hearing impairments are far more common than pre-lingual impairments.

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Pre-lingual deafness

:Main article: Prelingual deafness

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Prelingual hearing impairment exists when the impairment is congenital or otherwise acquired before the individual has acquired speech and language, thus rendering the disadvantages more difficult to treat because the child is unable to access audible /spoken communication from the outset. It is important to note that those children born into signing families have no delay in language development and communication. Most pre-lingual hearing impairment is due to an acquired condition, usually either disease or trauma therefore families commonly have no prior knowledge of deafness.

Related Topics:
Prelingual hearing impairment - Congenital - Speech - Language

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Post-lingual hearing impairment

:Main article: Post-lingual hearing impairment

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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 includes 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.

Related Topics:
Disease - Trauma

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Hard-of-hearing

People who are hard-of-hearing have moderate amounts of hearing loss but not enough to be considered deaf.

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The phrase hard-of-hearing, normally used as an adjective or adverb, can also be used as a noun, referring to people with hearing impairment as the hard-of-hearing. People who consider themselves culturally deaf, prefer the term "hard-of-hearing" or "deaf", and perceive "hearing impaired" as an insult.

Related Topics:
Hearing impairment - Culturally deaf

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Hearing impaired persons with partial loss of hearing may find that the quality of their hearing varies from day to day, or from one situation to another or not at all. They may also, to a greater or lesser extent, depend on both hearing-aids and lip-reading. They may perhaps not always be aware of it, but they do admit to it being important to see the speaker's face in conversation.

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Many people with hearing loss have better hearing in the lower frequency ranges (low tones), and cannot hear as well or at all in the higher frequencies.Some people may merely find it difficult to differentiate between words that begin with consonantal sounds such as the fricatives or sibilants, z, or th, or the plosives d, t, b, or p. They may be unable to hear thin, high-pitched or metallic noises, such as birds chirping or singing, clocks ticking, etc. Often, they are able to hear and understand men's voices better than women's.

Related Topics:
Fricatives - Sibilants - Plosive

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Others will find their condition so much worse if circumstances in their immediate environment affect the way they are able to use their hearing-aids, or prevent them from employing their lip-reading skills. A room with a high ceiling and a lot of reverberation will affect the sound of a speaker's voice adversely. The position of the listener, too, sitting at a right angle to the speaker at a long seminar table, thus being able to hear only with one, maybe the ineffectual ear, can make a difference. Difficulties can also arise for the listener trying to lip-read, if the speaker is sitting with his back against the light-source and is in this way obscuring his face. A rule of thumb is that bright lighting is to the hearing-impaired what noise is to the hearing; a source of distraction.

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The speaker's accent; the topic under discussion, possibly with many unfamiliar words; the softness of his voice; possibly his having a speech impediment; a habit of holding a hand in front of his mouth or turning his face away at times: all these tendencies cause problems to the hard-of-hearing, especially when they have to rely on lip-reading. The rustling of papers, and notebook pages being turned are precisely the noises that will be the first thing hearing-aids pick up.

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Unilateral hearing loss

People with unilateral hearing loss (single sided deafness/SSD) can hear normally in one ear, but have trouble hearing out of the other ear.

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Problems with this type of deficit is inability to localize sounds (ie. unable to tell where traffic is coming from)

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and inability to process out background noise in a noisy environment, such as in a restaurant.

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