| 摘要 |
PURPOSE:To hear only the favorite channel sound with a good articulation by a heater at a microphone position by cancelling a signal at a sound field instead of an electric system and preventing the interference of the sound of plural channels in a loud speaker. CONSTITUTION:First, switches 15 and 16 are closed, switches 14 and 19 are opened and switches 17 and 18 are set to the position connected to a terminal (b). To the characteristic of the first acoustic channel composed of an acoustic room 20, a speaker 15 and a microphone 23, the contents of the coefficient register of the first adaptive filter 24 are identified. Thus, the contents of an H register 67 are converged to the impulse response of the acoustic channel, after the first adaptive filter 24 is converged, the switch 16 is released and the contents of the register are fixed. Next, the switch 15 is opened, the switch 14 and the switch 19 are closed, and the switches 17 and 18 are located at the position connected with the terminal (b). Consequently, the H register of the second adaptive filter 28 is converged to the characteristic of the second acoustic channel and the characteristic of the first adaptive filter 24, namely, the characteristic inverting the phase of the ratio of the characteristic of the first acoustic channel. |
