How do sound vibrations travel through the cochlea?

Sound vibrations travel through the cochlea as mechanical pressure waves, a process that converts physical energy into electrical signals for the brain.1

The process occurs as follows:

• Entry: The stapes footplate vibrates against the oval window, creating pressure waves in the perilymph of the scala vestibuli.12
• Transmission: These waves travel through the cochlear fluids, causing the basilar membrane to vibrate. Because the membrane varies in stiffness and mass along its length, different frequencies cause maximum vibration at specific locations—high frequencies at the base and low frequencies at the apex.123
• Dissipation: The waves move around the helicotrema into the scala tympani and dissipate at the round window, which acts as a relief valve.143
• Transduction: The vibration of the basilar membrane causes the organ of Corti to move against the tectorial membrane. This creates shearing forces that bend the stereocilia of the hair cells, triggering the release of neurotransmitters and generating nerve impulses that travel to the brain via the cochlear nerve.152