The job of the ear is to turn sound waves in the air into electrical nerve impulses that travel to the brain. The ear thus occupies a key "interface" position between the physical and the psychological aspects of sound. The ear is an interesting organ on many levels. Because sound waves usually contain only minuscule amounts of physical energy, the ear has to be phenomenally sensitive, and it is a marvel of "biological engineering". But such a delicate structure is also fragile, and hearing impairments most often originate from damage to the ear, rather than to higher order processing stations in the brain. The anatomy and physiology of the ear is described in chapter 2 of "Auditory Neuroscience" . These web pages provide material to complement that chapter.
Making sense of sound