1. A musical keyboard instrument operating by alternating currents of electricity which, on impulse from the keyboard, produce music at a distant point via telephone lines.
2. An instrument for producing music at a distant point, or points, by means of alternating currents of electricity controlled by an operator who plays on a keyboard.

The music is produced by a receiving instrument similar to, or analogous to, the telephone; but not held to the ear. The pitch corresponds with the frequency of the alternation of currents.