| 摘要 |
<p>PURPOSE: To provide a high stability electronic noise elimination system perfectly discriminating a pipe path noise becoming a noise elimination object from an external noise with a simple system and updating a filter coefficient of a digital filter only for the pipe path noise becoming the noise elimination object. CONSTITUTION: When the filter coefficient of an adaptive digital filter 33 outputting a driving signal to a speaker 13 is updated, an arithmetic and logic unit 100 obtains a mutual correlative function between these output signals based on output signals from a first microphone 11 and a second microphone 12, and calculates a time lag T1 when the obtained mutual correlative function becomes a maximum, and outputs the time lag T1 to a comparator 102. The comparator 102 compares the time lag T1 with the time lag T2 by a distance difference between the first microphone 11 and the second microphone 12, and when these time lags disagree, a switch of a contact circuit 104 is connected to a contact 1 side, and an error signal 0 is inputted to a calculating circuit 91. Thus, the filter coefficient is updated only for the pipe path noise.</p> |
