Here's a breakdown of its role:
1. Sound Waves to Fluid Waves:
* Sound waves enter the ear canal and vibrate the eardrum.
* These vibrations are transmitted through tiny bones (ossicles) in the middle ear to the oval window, a membrane at the entrance of the cochlea.
* The vibration of the oval window creates pressure waves in the fluid inside the cochlea.
2. Sensory Hair Cells:
* The cochlea is divided into three fluid-filled chambers.
* The middle chamber, called the cochlear duct, contains a specialized structure called the organ of Corti.
* The organ of Corti contains thousands of tiny sensory hair cells.
* These hair cells are embedded in a membrane called the basilar membrane, which runs along the length of the cochlea.
3. Frequency Detection:
* The basilar membrane is narrower and stiffer at the base of the cochlea and wider and more flexible at the apex.
* Different frequencies of sound cause different parts of the basilar membrane to vibrate.
* High-frequency sounds cause vibration near the base, while low-frequency sounds cause vibration near the apex.
* This vibration of the basilar membrane bends the hair cells in the organ of Corti.
4. Signal Transduction:
* When the hair cells are bent, they release neurotransmitters.
* These neurotransmitters transmit signals to the auditory nerve, which carries the information to the brain.
5. Sound Perception:
* The brain interprets the signals from the auditory nerve to create the perception of sound, including pitch, loudness, and timbre.
In summary, the cochlea converts sound waves into electrical signals that the brain can interpret. This allows us to hear and understand the world around us.
