 Type
of hearing loss |
|
| |
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Degree of hearing
loss |
| |
Damage of any part along the auditory pathway
will affect our hearing ability. Normal hearing people can hear
sounds as soft as 25 dB HL between 250 Hz (low pitch) and 8000
Hz (high pitch). Hearing level exceeds this normal range will
be considered as hearing loss. The degree of hearing loss is
universally classified into 5 categories: |
|
| Mild
loss |
hearing levels between
26 to 40 dB HL: difficult to hear soft sounds
& whispers.
|
| Moderate loss |
hearing levels between 41 to
55 dB HL: speech must be loud to be heard; difficult
to hear distant speech; some difficulties in group
discussion or meeting.
|
| Moderately severe
loss |
hearing levels between 56 to
70 dB HL: very difficult to hear in noisy places,
group discussion or meeting.
|
| Severe loss |
hearing levels between 71 to
90 dB HL: extremely difficult to hear environmental
sounds; unable to hear speech beyond 25 cm (12
inches) from ear.
|
| Profound loss |
hearing levels below 91 dB HL:
can barely hear sounds; rely on lip-reading in
daily communication.
|
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Types of hearing
loss |
| |
There are three general types of hearing loss: |
| |
1. |
Conductive hearing loss |
|
|
Caused by outer and/or middle ear problems, such as malformation
of the ear structure, outer ear infection, earwax impaction,
perforated eardrum, middle ear infection and otosclerosis. |
| |
| |
2. |
Sensori-neural hearing loss |
|
|
Caused by damage or degeneration of the inner ear hair cells,
and/or by auditory pathway damage or pathology, such as aging,
prolonged noise exposure, head trauma, post-chemotherapy and
tumor. |
| |
| |
3. |
Mixed hearing loss |
|
|
Mixture of conductive and sensori-neural hearing loss. |
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