| 摘要 |
PROBLEM TO BE SOLVED: To provide an active type noise reducing device preventing a user from hearing a noise emitted from an adaptive notch filter even if an engine pulse varies abruptly. SOLUTION: The active type noise reducing device to cancel the vibrational noise on the basis of the output of the adaptive notch filter 4 is configured so that an engine pulse monitoring means 25 breaks a switch 26 to stop the output from the filter 4 when the change amount of the current value of the engine pulse fed to the filter 4 with respect to the corresponding past value within the specified time is equal to or has exceeded the specified value, and when the engine speed has varied steeply, the output of the filter 4 is stopped before the updating speed of the filter factor can no more make following-up to cause the filter 4 to make dispersion, and thereby generation of noises is precluded. COPYRIGHT: (C)2006,JPO&NCIPI
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