a device used by a person with hearing loss to emphasize a single specific sound. Unlike conventional hearing aids, which amplify all sounds in the environment, assistive listening devices focus on a single sound, such as the voice of a person with whom one is conversing in a noisy restaurant, and make it more prominent than the background noise. An assistive listening device typically consists of a transmitter and microphone that are placed near the source of the sound in which one is interested and a receiver and output device, such as headphones, that direct the sound to a particular individual.