What are these hair cells?
Under a microscope, they look as though they have a tiny hair protruding from them so they are called hair cells. Stereocilia are the organ made of hair cells, and they bend in response to sound or other mechanical influence. There are two types: auditory and vestibular. Auditory hair cells, which detect sound, are located in the cochlea of the inner ear. Movements of the stereocilia are transmitted to the brain and interpreted as sound.
Our sense of balance is also made possible through vestibular hair cells. These are located in vestibular organs.
Besides loud noises, ototoxic drugs (drugs which damage the hearing), lyme disease and other bacterial infections, viral infections, and trauma can all damage hair cells.