Sound amplification by stimulated emission of radiation of the laser. In a SASER device, a source (e.g., an electric field as a pump) produces sound waves (lattice vibrations, phonons) that travel through an active medium. In this active medium, a stimulated emission of phonons leads to amplification of the sound waves, resulting in a sound beam coming out of the device. The sound wave beams emitted from such devices are highly coherent. The first successful SASERs were developed in 2009. Instead of a feedback-built wave of electromagnetic radiation (i.e., a laser beam), a SASER delivers a sound wave. SASER may also be referred to as "phonon laser",
A/B Sound System eliminate the comb-filtering effect.” An A/B system is used in the Avon Theatre at the Stratford Festival in Canada. Stratford Festival sound designer William Fallon said, "I've found that it has also helped in creating separation and clarity in large production numbers, by being able to send half the cast down one path and the other half down another, either based on parts, blocking, leads vs ensemble, etc." A/B Sound System An A/B Sound System is a type of Sound reinforcement system or Public address system. Unlike a more typical sound reinforcement system, an A/B Sound System provides two electrically