Fig 7-33 shows that hair cells are supported on the basilar membrane , the whole apparatus vibrates up and down with the pressure waves. The cilia of the hair cells are stuck in a dense tectorial membrane . The vibrations cause a shear force on the cilia Fig 7-34 p 246. This means that the basilar membrane neat the oval window vibrates in sympathy with high frequency sound and near the center of the cochlea, it vibrates in sympathy with lower frequency sound. Shearing the hair cells one way hyperpolarizes the cells and the other way depolarizes the cells.
Nerve cells attached to the hair cells depolarize from the hair cells.
Lateral inhibition actively pinpoints the frequency of sound in our brains. They can produce pulses of high voltage, low amperage current as in fresh water species or low voltage, high amperage current in marine species. The current flows out from the electric gland and is monitored by modified hair-cells in the lateral line system. As you know, some fish have increased the current enough to stun a horse. At least some sharks can detect prey hidden under the sand by detecting the electrical output of their muscles as they respire.