| 摘要 |
PURPOSE:To collect sound by using plural directivity microphones and a time delay circuit, making only a signal of objective sound coincident on a time axis so as to add and synthesize it thereby emphasizing a sound at a specific location (object sound) more than a sound at other place (noise). CONSTITUTION:In taking a distance from a microphone M1 to a sound source P as L1 and a distance from a microphone M2 to the sound source P as L2 (L2> L1, the time difference tau of times when the object sound S irradiated from the sound source P is incident to the microphones M1, M2 is (L2-L1)/C. Then the output of the microphone M1 near the sound P is fed to a time delay circuit 1, subject to time delay of tau under the control of a clock pulse contol circuit 4 and fed to an adder 2 together with the output of the microphone M2. On the other hand, the output of the clock pulse control circuit 4 is converted into a DC control voltage and a low frequency cut-off frequency fc of a voltage controlld filter VCF3 is controlled based on the control voltage proportional to the clock pulse. |
