Which part of the ear contains actual hearing organ?
Your friend is correct,
The inner ear contains the main hearing organ called Cochlea. It is a circular or snail shaped fluid-filled bone that contains hair cells. Sound waves in the cochlea cause the hair cells to bend. Hence, the electric impulses generated in the cochlea are carried by the auditory nerve to the brain where sound is analysed.
@DKK...Good work..Keep posting!