| 摘要 |
PURPOSE:To improve the talking quality in a loudspeaker talking equipment by adding the 2nd microphone close to a talking microphone, measuring the acoustic intensity of the both and discriminating the presence or absence of an object signal so as to control a sequential estimation circuit. CONSTITUTION:The 2nd microphone 12 placed close to the transmission microphone 3 is installed to a location near the speaker 2 on the axis. A voice band component is extracted from the output of the transmission microphone 3 and the 2nd microphone 12 through bans pass filters 131, 132 respectively and inputted to an intensity measuring circuit 14. When the component of the acoustic intensity in a direction from the microphone 3 to the 2nd microphone 12 is positive, it represents that the object signal N(t) is dominant and when negative, it indicates that an echo signal y(t) is dominant. Thus, an adaptive operation control circuit 15 compares the fluctuation of the reception signal x(t) with that of the acoustic intensity, then the addition/interruption of the object signal is discriminated. Then through the discrimination, the estimate circuit 7 is controlled, and when the object signal N(t) is added, the sequential estimate of a pseudo echo path 8 is inhibited and when interrupted, the sequential estimate is restarted.
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