Part 1: The Outer Ear
The outer ear comprises of the pinna at the side of the head, a canal through which sounds travel and at the end of the canal, the eardrum. The ear canal is curved and irregularly shaped and it is approximately 2.5 cm in length and 8 mm in diameter. The curvature of the ear canal prevents the gathering of water and other foreign materials in the canal. The ear canal also keeps the eardrum at a constant temperature and humidity. The outer portion of the ear canal is relatively soft, while the inner part is hard and bony. The ear canal is closed at one end by the eardrum. The wall of the ear canal contains glands, which secrete earwax (cerumen). The outer ear serves to localize, collect, lead and enhance sounds. It also functions as a protective mechanism for the middle ear.

Part 2: The Middle Ear
The middle ear is the air-filled space located behind the eardrum. In the middle ear cavity there are three small bones called the ossicles; these are the hammer, the anvil and the stirrup. When sound makes the eardrum vibrate, the chain of bones is set into vibrations, and the stirrup induces a wave movement in the (lymphatic) liquid in the inner ear.

Part 3: The Inner Ear
The inner ear is filled with fluids and many microscopic components, all of which behave like a microphone. When the liquid is set into movement, it will then set the Basilar Membrane and the hair cells into vibration. Different hair cells correspond to different sounds with the low frequency sounds placed at the top of the cochlea and the high frequency sounds at the bottom. The vibration will thereby convert sound waves into a message that travels to the brain via the auditory nerve.