Britannica Sources used in this answer

How do hair cells in the organ of Corti respond to sound vibrations?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Cross-section diagram of the human ear showing the outer ear, middle ear, and inner ear, with labeled parts including the auricle, auditory canal, tympanic membrane, ossicles, cochlea, semicircular canals, and nerves. — human ear Structure of the human ear.

In the organ of Corti, hair cells respond to sound vibrations through a process of mechanical transduction. When sound waves cause the basilar membrane to vibrate, the organ of Corti moves against the tectorial membrane.12

This movement creates shearing forces that displace the stereocilia located at the top of the hair cells. The response depends on the direction of this displacement:1

Depolarization: When stereocilia are bent toward their tallest side, ion channels open, allowing potassium ions to flow into the cell. This excites the hair cell, triggering the release of neurotransmitters at its base.1
Hyperpolarization: When stereocilia are bent in the opposite direction, the ion channels close, inhibiting the cell.1

The released neurotransmitters stimulate the nerve fibres of the cochlear nerve, which then transmit electrical signals to the brain. Additionally, outer hair cells can contract rhythmically to modify and enhance the sensitivity and frequency discrimination of the inner hair cells.12