ABSTRACT
The ear detects sound pressure waves and is divided into three sections. The outer ear and middle ear function to transmit pressure waves to the inner ear, the cochlea. Sound waves are coded into neural impulses in two ways. Nerve firing rates follow the frequency of the sound at low frequencies, while at higher frequencies coding is determined by the point of maximum displacement on the basilar membrane. Hearing loss can be caused by loud noise and may be permanent if exposure is regular and prolonged; it is also a common feature of the ageing process. Sound waves are pressure changes in a fluid medium, usually air, which are caused by the vibration or movement of an object. The ear has three regions: the outer, middle and inner ear. Presbyacusis initially affects sensitivity to high frequency sounds, but losses at progressively lower frequencies occur with advancing years.
