ICSE Class 8 Answered

Mechanism of Hearing:

The pinna collects the sound waves and conducts them to the auditory canal.

Sound waves struck at the ear drum and set it into vibration.

Eustachian tube equalizes the pressure on either side of the ear drum and thus allows it to vibrate freely.

Ear drum transmits the vibrations to ear ossicles.

First two ear ossicles i.e. malleus and incus magnify the vibrations of the third ear ossicle i.e. stapes.

Stapes then transmits the vibrations to the oval window which set the fluid in cochlear canals into vibrations.

Fluid in the cochlear canal stimulates the sense cells present in the cochlea to vibrate.

Finally the vibrations are sent to the brain in the form an impulse via auditory nerve.