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Hearing Loss : A Partial Or Total Loss Of Hearing

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Hearing loss can simply be defined s a partial or total loss of hearing and can be classified into three main types viz; Conductive loss where mainly the outer or middle ear function is affected, sensorineural hearing loss which involves the damage to cochlea or the auditory nerve and mixed hearing loss having both conductive as well as sensorineural components present. Mechanism involved in normal hearing is very complex. Sound waves enter the outer ear and set the tympanic membrane into vibrations. These vibrations are conveyed via the ossicular chain to the inner ear through the oval window setting the inner ear fluids and the basilar membrane in motion. These vibrations take form of “travelling wave” that travels from the base of the cochlea to the apex. This wave peaks at the place tuned to the frequency and dies away rapidly. These in turn stimulate the sensory hair cells of organ of Corti which activate the auditory nerve and the signal is now a neural code that can be processed by the nervous system (Gelfand, 2009). Damage to any part of the ear, thus disrupts the hearing mechanism and results in hearing loss of varying degrees depending on the severity and the site of destruction. Ototoxicity, trauma, noise exposure, ageing, infections , tumors, temporal bone fracture etc are few of the many other reasons that disrupt the hearing mechanism and elevate the hearing thresholds. Prevalence of hearing loss dropping with age has been well documented and falls below 35%

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