Question

(c) How do you hear a sound?

Answer 1

Part 1: Mechanism of hearing
We hear sound due to the presence of the ear (a sense organ) which is sensitive to sound.

• The pinna of the external ear collects sound waves which pass through the external auditory meatus all the way to the eardrum.
• These vibrations are passed from the eardrum to the malleus, incus and stapes of the middle ear which causes an increase in the frequency of the vibrations.
• The vibrations furthermore are passed to the cochlea of the inner ear through the oval window.
• These vibrations in the endolymph of the cochlea cause vibrations to be induced in the basilar membrane, which in turn cause the sensory hair of the organ of corti to vibrate.
• The receptor hair cells force themselves against the tectorial membrane, converting sound energy to a nerve impulse or action potential.
• This nerve impulse is transmitted to the auditory cortex of the brain, where the impulse is evaluated and analyzed causing the sound to be recognized.