(a) Outer Ear: Pinna, auditory canal and tympanic membrane.

Pinna: It collects the sound from the surroundings.

Auditory Canal: The sound waves collected passes through this canal.

Tympanic Membrane: It is a thin membrane which receives the vibrations of sound. A compression reaches the eardrum, the pressure on the outside of the membrane increases and pushes the eardrum inward, and moves out when the rarefaction reaches.

(b) Middle Ear: Consists of three small bones called hammer, anvil and stirrup. The vibrations are received by these three bones and the strength of vibrations is increased i.e., the sound is amplified and passed to inner ear.

(c) Inner Ear: It consist of cochlea and auditory nerve.

Chochlea receives the amplified vibrations and convert them into electrical signals. These electrical signals are sent to the brain via the auditory nerve and the brain interprets the signals as sound.