Patent ID: 8098841

Claim:
A sound field controlling apparatus for a public address system, the sound field controlling apparatus comprising: a plurality of microphones that inputs a sound signal corresponding to a sound of a sound source; at least one loudspeaker that outputs the sound signal input by one of the microphones; a sound source position detector that detects a position of the sound source and selects at least one of said microphones as an address microphone based on the detected position of the sound source; a signal processor that processes the sound signal input by the address microphone and comprises, corresponding to each output line of each of said at least one loudspeaker, a delay device, an equalizer and a volume controlling attenuator, wherein the delay device adds a delay time corresponding to a distance between the position of the sound source and the corresponding loudspeaker to the input sound signal for making a sound output by the corresponding loudspeaker reach a listener within a predetermined time from a direct sound of the sound source, and the equalizer and attenuator control an equalizing property and an output level of the input sound signal for flattening a frequency response of sound feedback between the corresponding loudspeaker and the address microphone, wherein the signal processor further comprises, corresponding to each output line of each of said at least one loudspeaker, a finite impulse response (FIR) filter that convolves a negative coefficient of a same amplitude and a same timing to each of signals corresponding to sounds repeatedly output from the corresponding loudspeaker and input to the address microphone except a signal corresponding to a first sound output from the corresponding loudspeaker in order to flatten a frequency response of sound feedback between the corresponding loudspeaker and the address microphone.