| 摘要 |
PURPOSE:To surely prevent howling and ring tone by using an echo canceller so as to reduce a bypassed voice signal from a speaker received by 2 microphones. CONSTITUTION:When an echo canceller 6 corrects an adaptive filter 52 only if a voice from a speaker 9 only is inputted to microphones 1a, 1b, the same waveform as that of a signal via a delay circuit DL4 is generated from a bypassed voice signal 9a. Thus, the two signals are subtracted by a subtractor 51 to make it possible that the transmission signal is made nearly zero. That is, the bypassed signal from the speaker 9 toward the microphones 1a, 1b when viewing from a transmission reception circuit 7 is nearly zero. |
