Hearing

The sense that enables sound to be perceived. The ear transforms the sound waves it receives into nerve impulses that pass to the brain. Each ear has 3 distinct regions: the outer, middle, and inner ear. Sound waves are channelled through the ear canal to the middle ear, from where a complex system of membranes and tiny bones conveys the vibrations to the inner ear. The vibrations are converted into nerve impulses in the cochlea. These impulses travel along the auditory nerve to the medulla of the brain. From there, they pass via the thalamus to the superior temporal gyrus, part of the cerebral cortex involved in perceiving sound. (See also deafness.)