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 Sound Like Someone Trying Not to Make a Sound confront their fears." Liz Rosenburg, reviewing for the "Boston Globe" concluded, "It may not be for everyone, certainly not for the most timid, but it has a satisfying and haunted originality that will win its own fans." A Sound Like Someone Trying Not to Make a Sound A Sound Like Someone Trying Not to Make a Sound (Doubleday Books for Young Readers, September 28, 2004, ) is a children's picture book written by John Irving and illustrated by Tatjana Hauptmann. The title was originally used for a children's book written by a fictional character (Ted Cole) in Irving's 1998 novel