Most powerful electro-acoustic speaker

The Hyperspike HS-60, invented by Curt Graber of Wattre Corporation, USA, is an Acoustic Hailing Device (AHD) emitter capable of producing a coherent beam of sound, like a laser in the human voice range. In certified field tests conducted in March 2007 its coherent beam length was measured at 264 m and output was measured at 140.2 db at 128 m range, using less than 3 Kw of electricity. Its output is equivalent to 182 dB 1m from the source and, under optimal conditions it can transmit audible voice communications to a target over a distance of more than 3 km (2 miles).