The Laser Listener, created in July 1994, was a low-cost experiment in reconstructing audio from window vibrations. Such systems are rumored to be used by the United States Government for surveillance purposes and this project was an attempt to prove the concept. A 5mW HeNe visible red laser was aimed onto the target window and the reflected laser light, now modulated by the vibrating window, was captured by a phototransistor and fed through a high-gain amplification system.