Describe how the ear converts sound into messages that the brain can interpret.

Sound is directed down the ear canal to the ear drum, and then via the tiny middle ear bones (the smallest bones in the body) to the inner ear, which houses the sensory organ of hearing. This organ rests on a membrane that vibrates selectively to different sound frequencies, and so acts as a sound filter, which sorts sound frequencies into groups. High frequencies produce maximal vibrations at the beginning of the coiled inner ear, and low frequencies do the same at the other end.