A mobile sound booster and infrared device that you can use to listen to the stereo or tv. Microphones in the receiver let you hear activity and noises around you as well. If you are in a theatre or a concert hall equipped for infra-red transmission, you can adjust the volume at the receiver to suit your individual taste. This allows you to enjoy the event in optimum sound quality. For more information read our blog here:- Sennheiser Set 900 Assistive Listening device