If the air conduction thresholds show a hearing loss but the bone conduction thesholds are normal, this is called a conductive loss of hearing. The sounds are being processed correctly at the inner ear, but the vibrations are not reaching it. This can sometimes be corrected by surgery. The maincauses for conductive loss of hearing are
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blockages – build up of wax or fluid.
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Accidents – the eardrum may be punctured or the middle ear damaged.
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Diseases – the bones in the middle ear can be prevented from moving.
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Age – with increasing age, the bones in the middle ear can become solidified.
A normal audiogram is shown below left, and one indicating conductive hearing loss in the left ear (hence the > symbols) is shown below right. The readings are significantly below normal.
