| 摘要 |
PURPOSE:To radiate the amplified sound wave of the transmitter without causing howling by minimizing the amplitude of the sound wave at a receiver position where the sound wave in a medium is received by interference among sound waves radiated at respective positions of the transmitter. CONSTITUTION:The sound wave received by the receiver 1 is amplified by an amplifier 2 for the receiver, passed through amplifiers 3a-3c, and sound waves 5a-5c are radiated into the medium by transmitters 4a-4c. At this time, the amplification factors and phase characteristics of the amplifiers 3a-3c for the transmitters are varied so that the sum of the sound waves at the position of the receiver 1 becomes 0, and then the sound waves outputted by the transmitters 4a-4c are not received by the receiver 1. Consequently, the receiver 1 can receive only the sound wave 9 from an external sound source 8 except the transmitters at all times. For the purpose, the sensitivity of the receiver 1 is increased to obtain a long distance between the sound source 8 and the receiver 1, and speeches of persons in a wide area can be received by one receiver at a conference, etc. |
