Hearing aids are primarily useful in improving the hearing and speech comprehension of people who
have hearing loss that results from damage to the small sensory cells in the inner ear, called hair cells.
This type of hearing loss is called sensorineural hearing loss. The damage can occur as a result of
disease, aging, or injury from noise or certain medicines.
A hearing aid magnifies sound vibrations entering the ear. Surviving hair cells detect the larger
vibrations and convert them into neural signals that are passed along to the brain. The greater the
damage to a person’s hair cells, the more severe the hearing loss, and the greater the hearing aid
amplification needed to make up the difference. However, there are practical limits to the amount of
amplification a hearing aid can provide. In addition, if the inner ear is too damaged, even large vibrations
will not be converted into neural signals. In this situation, hearing aid benefit may be limited and
appropriate hearing aid devices may be recommended.
Some individuals with conductive hearing loss (a loss occurring from the middle ear) may also benefit
from hearing aids. Patients with conductive losses who opt not to have surgery often do very well with