Two pin plugs are commonly seen on body-worn hearing aid cords and other hearing diagnostic equipment such as audiometers and auditory trainers where mono connections are required. Recent innovations in the professional music world have the two pin design in monitor cords that numerous artists wear. When in a Y or V cord configuration, one wired to each ear creates a true stereo or binaural sound. Polarized plugs quickly orient the grounding pin to the right socket connection.
Audio Connector 
