| 摘要 |
PURPOSE:To improve the instantaneousness and accuracy of a signal processing without using any special signal for control by connecting a measuring system and a reproducing system in a loop, and using an adaptive filter. CONSTITUTION:A microphone 14 is disposed opposingly in the front of a speaker 13 and they are connected in an acoustic space. Between the microphone 14 and a sound source signal input terminal part 10, a signal delay circuit 15, a characteristic setting part 16, and an error detecting part 17 are connected in this order toward the microphone 14. The delay time of the circuit 15 is set at a time generated by adding the half of the impulse response time of the adaptive digital filter part 11 to the acoustic wave propagation time between the speaker 13 and the microphone 14. The filter part 11 is self-adjusted so that the mean square of the error information signal values of errors between signals from the microphone 14 and output signals obtained from the detection part 17 becomes minimum. By setting the transfer function of the setting part 16 in one, the characteristic of the filter part 11 becomes inverse to that of the speaker 13, and the overall characteristic becomes flat. |
