An electronic device worn in or behind the ear by people with hearing problems that makes sounds louder.

A hearing aid is a small electronic device that you wear in or behind your ear. It makes some sounds louder. A hearing aid can help people hear more in both quiet and noisy situations. Hearing aids help people who have hearing loss from damage to the small sensory cells in the inner ear. The damage can occur as a result of disease, aging, or injury from noise or certain medicines. There are different types of hearing aids. They differ by size, their placement on or inside the ear, and how much they amplify sound. The hearing aid that will work best for you depends on what kind of hearing loss you have and how severe it is. If you think that you need a hearing aid, you have two different options: Over-the-counter (OTC) hearing aids, which you can buy directly. You don't have to get a hearing exam from a healthcare professional first. OTC hearing aids are for adults who have mild to moderate hearing loss.; Prescription hearing aids, which you get from an audiologist (a health professional who specializes in hearing and balance disorders). The audiologist will program the hearing aids, based on how severe your hearing loss is. You may need prescription hearing aids or other devices if you have significant or complicated hearing loss. NIH: National Institute of Deafness and Communication Disorders

Wearable sound-amplifying devices that are intended to compensate for impaired hearing. These generic devices include air-conduction hearing aids and bone-conduction hearing aids. (UMDNS, 1999)

Hearing aid, device that increases the loudness of sounds in the ear of the wearer. The earliest aid was the ear trumpet, characterized by a large mouth at one end for collecting the sound energy from a large area and a gradually tapering tube to a narrow orifice for insertion in the ear. Modern...