Sound waves hit the eardrum, Compression forces the eardrum inward, Rarefaction forces the eardrum outward, due to pressure, The eardrum vibrates at the same frequency as the sound wave, The small bones connected to this also vibrate at the same frequency (stirrup bone), Vibrations of the bones transmitted to the fluid in the inner ear, Compression waves are thus transferred to the fluid (in the cochlea), The small hairs that line the cochlea move too, Each hair is sensitive to different sound frequencies, so some move more than others for certain frequencies, The hairs each come from a nerve cell, when a certain frequency is received, the hair attuned to that specific frequency moves a lot, releasing an electrical impulse to the brain, which interprets this to a sound