| 摘要 |
PROBLEM TO BE SOLVED: To attain the communication of loud voices with high sound quality and with no generation of echoes by deciding the phase shift value that affects the voice signals by every phase shift means, so as to reduce the components resulting from the voices which are reproduced by a loudspeaking means from among the added voice signals. SOLUTION: Microphones 3-6 are placed at the same angle interval on the circumference of a circle set around a speaker 2, and the phase shift values of the phase shifters 7A, 7B, and phase splitters 8A and 8B are fixed at all frequency levels. The phase shift values differ between the adjacent shifters 7A/7B and adjacent splitters 8A/8B by 360/N degrees (N: an integer is larger than or equal to 3) in the order of disposition of these phase shifters. The received speech signals are simultaneously collected by the microphones 3-6 and undergo the phase shift of 360/N individually. since the same distance is set between the loudspeaker 2 and each of microphones 3-6, the sounds outputted from the loudspeaker 2 are collected at the same level and with the same phase. Hence the phase-shifted signals are canceled each other when they are added together.
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