A hearing aid is a small electronic device that you wear in or behind your ear. It makes some sounds louder so that a person with hearing loss can listen, communicate, and participate normally in daily activities. A hearing aid can help people hear more in both quiet and noisy situations. However, only one out of five people, who would benefit from a hearing aid, actually use one.
A hearing aid has 4 basic parts: a microphone, computer processing chip, amplifier, and speaker. The hearing aid receives sound through a microphone, which converts the sound waves to electrical signals and sends them to an amplifier. The amplifier increases the power of the signals and then sends them to the ear through a speaker. Not all hearing aids process sound in the same way, each manufacturer has a slightly different algorithm for prescribing gain and compression. This algorithm is fundamental to ensuring maximum speech intelligibility and sound audibility, a hearing aid is much more than just an amplifier.
Hearing aids are primarily useful in improving the hearing, and speech comprehension for people who have hearing loss, as a result of damage to the small sensory cells in the inner ear, called hair cells. 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 is needed to make up the difference. However, there are practical limitations 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, a hearing aid would be ineffective.
There are several different styles of hearing aids. The styles differ by size, their placement on or inside the ear, and the degree to which they amplify sound.