Ear as a sound detector

The ear detects sound by passing vibrations through the outer, middle and inner ear. In the inner ear, sensory cells convert the vibrations into electrical signals that travel to the brain.

Outer ear: Collecting sound

The pinna, the visible outer part of the ear, collects sound waves and directs them along the auditory canal. The waves produce pressure variations in the air, causing the eardrum at the end of the canal to vibrate.

Middle ear: Transmitting vibrations

The vibrating eardrum moves three small bones called the ossicles: the malleus, incus and stapes. These bones pass the vibrations to a membrane called the oval window.

The ossicles also increase the pressure applied at the oval window. This helps transfer the vibrations from the air-filled middle ear to the fluid-filled inner ear.

Inner ear: Producing electrical signals

The moving oval window causes vibrations in the fluid inside the cochlea. These vibrations move structures within the cochlea, bending sensory hair cells. The hair cells convert this mechanical movement into electrical signals, which the auditory nerve carries to the brain.