The Mechanism of Hearing The human ear is divided into three parts. 1. the outer ear 2. the middle ear 3. the inner ear Air-conducted sound waves must move through these three parts in order for sound to be heard. The outer ear serves to channel the sound waves into the middle ear which is composed of three bones. These three bones mechanically transmit these waves to the oval window, which is part of the inner ear. The oval window vibrates inwardly, creating pressure waves in an incompressible