How We Hear

As the video shows (bottom, right), sound vibrations move through the air like waves moving across the water. Hearing begins when the vibrations reach the outer ear (see figure, 1), which acts to funnel the vibrations through the ear canal (2) toward the eardrum (3). Sound vibrations then interact with the eardrum, before transferring to a series of three tiny bones in the middle ear (4). These bones further amplify the vibrations of the eardrum, then transfer them to a sensory organ in the inner ear, the cochlea (5). Tiny sensory hair cells lining the cochlea (6) are responsible for transforming the sound waves into electrical signals that are interpreted in the cerebral cortex of the brain (see the video).