A hearing aid is a little computer. The Hearing aid consists of four basic components:
Hearing aids are primarily useful to people who have suffered sensorineural hearing loss from damage to the small sensory cells in the inner ear known as hair cells. The damage can be caused by disease, aging or injury from noise or drugs.
A hearing aid magnifies sound vibrations. Surviving hair cells detect the larger vibrations and convert them into signals that are sent to the brain.
There are limits to the amplification a hearing aid can provide. In addition, if the inner ear is too damaged, even large vibrations will not be converted into signals to the brain.