You searched for: “acousmatic
acousmatic (adjective), more acousmatic, most acousmatic
1. Relating to a class of scholars under Pythagoras who listened to his teachings without inquiring into their inner truths: The acousmatic pupils of the philosopher Pythagoras were required to sit in total silence while they listened to him deliver his lecture from behind a veil or screen so they might be able to concentrate better on what he was teaching them.
2. A reference to a sound, whether natural or produced, when the source of the sound is unseen or has no visually recognizable cause: In a mystery film, the prisoner could hear the acousmatic ringing of a bell from a source far above him.