Public addressing system

摘要

A sound-amplification apparatus comprises: an acoustic signal source for outputting an acoustic signal; an amplified sound source for receiving the acoustic signal from the acoustic signal source and radiating an amplified sound; a control sound source provided in a vicinity of the amplified sound source for radiating a control sound; and signal processing means for producing a control sound signal by controlling at least one of an amplitude and a phase of the acoustic signal from the acoustic signal source so that an acoustic space having a desired directionality is formed by interference between the amplified sound and the control sound, and providing the control sound signal to the control sound source.