How does the cochlea work?
Fright night shows some good insights into this question, and I think I may be able to add something to his answer, though this is at the limit of what is known/surmised about the cochlea. I may have misunderstood some of this! Firstly, there are two types of hair cell, inner and outer. Outer hair cells act as a kind of amplifier as I’ll try to explain later. The inner hair cell consists of a cell with a hair poking out into a fluid called endolymph (see later). When the fluid moves, it moves the hair, like grass in the wind. This movement caused the nerve connected to the hair cell to send a signal to the brain. Tuning: Fright night is right, a frequency will stimulate a number of hair cells, but there is a protein called prestin within an outer hair cell which contracts the hair cell to squirt endolymph (one of the fluids in the inner ear) over the inner hair cell, thus amplifying the signal, allowing the brain to work out which hair cell produced the biggest response and can therefo
