Question

Explain the mechanism through which a sound produces a nerve impulse in the inner ear.

Answer 1

1. The two sensory functions that the ear performs are hearing and maintaining the body balance.
2. Ear is divided into three parts – External ear, Middle ear and Internal ear.
3. The external ear collects sound waves and drives them towards the tympanic membrane (ear drum).
4. The ear drum vibrates in response to the sound waves and these vibrations are transmitted to the oval window through the ear ossicles. (Malleus, Incus and Stapes)
5. From the oval window, these vibrations are passed on to the fluid of the cochlea, where they generate waves in the lymphs.
6. The waves in these lymphs generate ripples in the basilar membrane.
7. Movements of the basilar membrane make the “sensory hair” of the receptor cells in the organ of corti move in the overlying tectorial membrane and get distorted.
8. As a result of this stimulation, nerve impulses are generated in the associated afferent neurons.
9. These impulses are transmitted to the auditory cortex of the cerebrum, via. auditory nerves.
10. The auditory cerebral cortex analyzes these impulses and interprets them as sound.