What are hearing aids? Hearing aids are sound-amplifying devices designed to aid people who have a hearing impairment. Most hearing aids share several similar electronic components, including a microphone that picks up sound; amplifier circuitry that makes the sound louder; a miniature loudspeaker (receiver) that delivers the amplified sound into the ear canal; and batteries that power the electronic parts. Hearing aids differ by: • design • technology used to achieve amplification (i.e., analog vs. digital) • special features Some hearing aids also have ear molds or earpieces to direct the flow of sound into the ear and enhance sound quality. The selection of hearing aids is based on the type and severity of hearing loss, listening needs, and lifestyle.