Definitions for "Headphone"
electro-acoustic transducer for converting electric signals into sounds; it is held over or inserted into the ear; "it was not the typing but the earphones that she disliked"
an audio device designed to allow the listener to hear music or conversations without disturbing others
a transducer that receives an electrical signal from a media player or receiver and uses speakers placed in close proximity to the ears to convert the signal into audible sound waves without causing any damage to the listener's ears
Keywords:  intercom, restroom
Intercom in the restroom.
Keywords:  plugging, tuning, jack, diameter, port
Jack This is usually a 1/4"-diameter jack for plugging in a pair of headphones for practice, tuning, etc.
Port for plugging in headphones.