| 摘要 |
PURPOSE:To reduce a noise in travelling at a part required actually and to fully display the characteristic of an acoustic device by attaching a simple mechanism on an ordinary acoustic device. CONSTITUTION:A sound collection microphone 1a is provided at the pillow of a driver sheet or the pillow part of an assistant sheet. Since sound from a speaker 7a and the sound other than that, i.e., the sound on which the noise is added can be detected at the sound collection microphone 1a as a sound field signal, a noise component can be obtained by subtracting a signal component equivalent to the sound from the speaker 7a from the sound field signal, and the noise can be negated by outputting the negative phase signal of the noise from the speaker 7a. Therefore, the signal of the sound detected by the highly directional microphone 1a is amplified so as to conform to the signal from a sound field signal source 6a and the output signal of a DSP 14a based on the relation of propagation characteristic and the amplification factor, and after that, it is A/D-converted, and a digital sound field signal can be outputted. The noise component is found from the signal in which the matching of strength is taken by the DSP 14a, and the negative phase signal is added on the signal from the sound field source 6a, then, it is outputted. |
