The functional unit of the ear is the cochlea. It's located in the inner ear, a complex, fluid-filled structure shaped like a snail shell.

Here's a breakdown of the ear's structure:

* Outer ear: This includes the visible part of the ear (pinna) and the ear canal. Its job is to collect sound waves.

* Middle ear: This contains the eardrum (tympanic membrane) and three tiny bones (ossicles). These bones vibrate in response to sound waves and transmit them to the inner ear.

* Inner ear: This is where the cochlea resides. It's filled with fluid and houses the organ of Corti, the actual sensory organ of hearing.

The cochlea converts vibrations into electrical signals that are transmitted to the brain via the auditory nerve, allowing us to perceive sound.