In 2369, while the senior officers from the USS Enterprise-D were held hostage on Arkaria Base, a hypersonic pulse was created by Dr. Beverly Crusher. This was achieved by modifying the emitters of Commander Geordi La Forge's VISOR, while Commander Riker and Counselor Troi distracted the guards. The resulting pulse of high-pitched sound was of a high enough frequency to knock everyone in the room unconscious, apart from Commander Data. (TNG: "Starship Mine")