Sound waves are collected by the outer ear and channeled down the auditory canal

A sound wave enters the outer ear and strikes the eardrum causing it to vibrate with the same frequency and amplitude as the wave itself.
This vibration is passed along to three tiny bones in the middle ear which intensify the force of the vibration.
The innermost bone pushes on a membrane that opens into the inner ear.
This creates a wave in the fluid-filled cochlea of the inner ear.
The cilia, or hair cells on the basilar membrane in the cochlea bend back and forth as the wave passes.
This causes the hair cells to initiate a signal that is passed along to the auditory nerve, which carries the signal to the brain.