A device to improve the hearing. Simple passive devices, such as ear trumpets, are now rarely used. An analogue hearing aid consists of a miniature microphone, an amplifier, and a tiny loudspeaker. The aid is powered by a battery and the whole unit is small enough to fit behind or within the ear inconspicuously. If necessary, aids can be built into the frames of spectacles. In a few cases of conductive hearing loss the loudspeaker is replaced by a vibrator that presses on the bone behind the ear and transmits the sound energy through the bones of the skull to the inner ear. Digital hearing aids are in some respects similar to analogue aids but in addition to the microphone, amplifier, and loudspeaker, they have digital-to-analogue converters and a tiny computer built into the casing of the aid. This enables the aid to be programmed to the patient’s particular requirements and generally offers improved sound quality. See also bone-anchored hearing aid, cochlear implant, environmental hearing aid, implantable hearing aid.
Subjects: Medicine and Health.