. Explain Mechanism of hearing


Best Answer

Mechanism of hearing

The sound waves from a vibrating object are collected and transmitted inwards by the external ear to tympanum. The vibrations of tympanum are conducted to the oval window of cochlea by the ear ossicles. The movement of the oval window generates pressure waves in the perilymph of vestibular canal. The pressure waves are later transmitted to the perilymph of tympanic canal. Finally sound waves are dissipated into the air of middle ear cavity through the vibration of the round window. During the transmission of pressure waves from vestibular canal to tympanic canal the vestibular and basilar membranes are made to vibrate. The vibrations of basilar membrane push the sensory hairs of hair cells against tectorial membrane, the displacement of hairs generate receptor potentials which induce the production of nerve impulses in the cochlear nerve fibres. These impulses are transmitted to the auditory cortex of the temporal lobe of the cerebrum. Here the information is analysed to understand the nature of sound. The audible range of human ear is 20 to 20,000 Hz. The distance the pressure waves travel from the oval window to the apex of cochlea depends on the frequency of sound waves. As the frequency of sound waves increases, the distance traveled decreases.

The low frequency waves have adequate time to travel in the form of pressure wave of the perilymph from the oval window to the round window through the vestibular canal, helicotrema and tympanic canal. As the frequency of sound waves increases, the pressure waves generated do not have time to travel all the way upto helicotrema. Hence they are transmitted through the vestibular and basilar membrane to the perilymph of tympanic canal.

 

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