Sound amplification by stimulated emission of radiation phenomenon, known as the Larsen effect, is the result of a positive feedback. In general, every oscillator consists of three main parts. These are the power source or pump, the amplifier and the positive feedback leading to the output. The corresponding parts in a SASER device are the excitation or pumping mechanism, the active (amplifying) medium, and the feedback leading to acoustic radiation. Pumping can be performed, for instance, with an alternating electric field or with some mechanical vibrations of resonators. The active medium should be a material in which sound amplification can be induced. An example of a feedback
A Moving Sound A Moving Sound A Moving Sound () or Sheng Dong is a Taiwanese music act consisting of vocalist/dancer Mia Hsieh, vocalist, bass guitarist and zhong ruan player Scott Prairie, erhu player I-Fang Chen, and zhong ruan player Chih-Ling Chen. In A Moving Sound’s music traditional Taiwanese music forms are reinterpreted to create new original song compositions. Instruments such as the erhu (fiddle), the zhong ruan (lute), and the transcendent vocals and dance of lead singer Mia Hsieh, transport listeners on a journey that Global Rhythm magazine described as “...delicately balanced between many worlds…an entryway to Eastern music and artful expression