Final answer:
Deflection towards the kinocilium opens ion channels through tension in the protein tethers, causing depolarization of the hair cell membrane and initiating nerve impulses to the cochlear nerve, which contribute to the perception of sound intensity.
Step-by-step explanation:
When the stereocilia on the hair cells of the organ of Corti bend towards the kinocilium, which is the tallest member of the stereocilia array, this movement causes tension in the protein tethers that link the stereocilia together.
This tension opens ion channels in the cell's membrane, leading to depolarization of the hair cell membrane. This depolarization ultimately triggers nerve impulses that travel down afferent nerve fibers to the cochlear nerve. The intensity of sound, or volume, that we perceive is related to how many hair cells are stimulated at a specific location within the basilar membrane.