Structure and Function: The Mechanism of Hearing

Our ability to hear depends on a complex series of events that occur in the ear. Sound waves in the air are transmitted as vibrations through a series of structures to the receptor for hearing, the organ of Corti in the inner ear. Inside the organ of Corti, these physical vibrations are detected by sensory hair cells, which respond by producing electrical signals. Nerves carry these signals to the brain, where they are interpreted. Sounds of different frequencies stimulate hair cells in different parts of the organ of Corti, allowing us to perceive the subtleties of sounds such as speech and music.


Hair cells in the organ of Corti

This highly magnified cross section shows hair cells in the organ of Corti. The electrical signals produced by these cells travel along the cochlear nerve to the brain.

Brain during auditory stimulation

Sound is processed in auditory areas on both sides of the brain, but speech is interpreted mainly on the left side. This PET scan was taken while the subject was listening to a song, stimulating activity on both sides of the brain.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

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