| 摘要 |
PURPOSE:To allow the small sized microphone equipment to collect only a sound incident on a desired direction and to suppress other sound properly. CONSTITUTION:A 1st microphone 11 to collect a desired sound and a 2nd microphone 21 having a directivity in which the sensitivity in the arrival direction of a desired sound is low are arranged close to each other, an output signal S21 of the 2nd microphone 21 is fed to a subtractor means 15 via an adaptive filter circuit 24, and the subtractor means subtracts an output signal of the adaptive filter means from the output signal S11 of the 1st microphone. The adaptive filter means is adjusted so as to minimize the output power of the subtractor means and the operation of the adaptive filter means is limited based on the output of a level ratio detection means 51 detecting a level ratio S21/S11 of output signals of both the microphones. |
