1Originally: of or relating to the production of sound in response to or by means of an electric current. In later use: specifically of or relating to the production of music by electronic means; (of music or other sound) produced electronically.
2Designating a sensation of sound produced by the passage of an alternating current or electromagnetic waves through the body; of or relating to such sensations.
3Designating acoustic signals emitted by conducting objects caused to vibrate by low-frequency electromagnetic waves; of or relating to such sounds.
Mid 19th century; earliest use found in John Timbs (1801–1875), author. From electro- + -phonic.