Back 30 Hearing

HUMAN EXPERIENCE IS enriched by our ability to distinguish a remarkable range of sounds—from the complexity of a symphony, to the warmth of a conversation, to the dull roar of the stadium. This ability depends upon the almost miraculous feats of hair cells, the receptors of the internal ear. Similar hair cells are also responsible for our sense of equilibrium. Human hearing commences when the cochlea, the snail-shaped receptor organ of the inner ear, transduces sound energy into electrical signals and forwards them to the brain. The cochlea, however, is not simply a passive detector. Our ability to recognize small differences in sounds stems from the auditory system's capacity to distinguish among frequency components and to inform us of both the tones present and their amplitudes. The cochlea also contains cellular amplifiers that augment our auditory sensitivity and are responsible for the first stages of frequency analysis.