hearing aid

7.17  hearing aid. Any wearable sound amplification device designed for, offered for the purpose of, or represented as aiding persons with hearing loss. Annotation         In general, hearing aids have internal microphones, amplifiers, and output transducers that are housed in the same physical unit and are air conduction devices. However, in some instances, the microphones and/or output transducers may be housed externally. Hearing aids are fit using audiometric and prescriptive methods.