RhymeZone: acousmatic definitions

Definitions of acousmatic:

adjective: Referring to a sound that has no visually identifiable cause.
adjective: Referring to Pythagorean disciples who for years listened to his lectures from behind a curtain, unable to see him.
adjective: (music) Referring to pre-recorded music that is presented in concert using loudspeakers, e.g. some types of computer music.

(Definitions from Wiktionary)