| 摘要 |
<p>PURPOSE:To increase the S/N ratio of a signal by synthesizing two out of three outputs of three directional microphones, centralized at one position, into two system signals, and performing processing on the basis of the coefficient of correlation between those two composite signals. CONSTITUTION:Directional microphones 11 and 12 for receiving ambient noises, and a directional microphone 13 for receiving an audio signal are centralized nearly at one point. Signals received by the microphones 11 and 13 are added by a mixing circuit 14, and those by the microphones 12 and 13 are added by a mixing circuit 15. The addition signals of those circuits 15 and 16 are processed by an adaptive filter part 16 on the basis of their correlation coefficient, and the resulting signal appears at a terminal 17. The microphones 11-13 each have 8-shape directional characteristics, and are provided having a 90 deg. difference in direction. Consequently, the filter part 16 adjusts the output in proportion to the value of the coefficient of correlation between the two input signals. Therefore, only a section containing a sound is outputted and a no-sound section containing only noises is suppressed, improving the S/N ratio of the signal.</p> |
