PURPOSE: To prevent a user from feeling displeasure by providing an abnormality detection part detecting the abnormality in a noise controller and interrupting the formation of a cancel sound according to the detection of the abnormality in the abnormality detection part.
CONSTITUTION: A switch being turned on by the pressure of a diaphragm due to abnormal large vibration is provided on the rear side of the diaphragm of a speaker 1 as a detector detecting the state where the output of the speaker 1 being an actuator becomes large abnormally, and an electrical circuit is formed by connecting a resistor and a battery to the switch. When the voltage of one end of the resistor is increased/decreased by the on/off of the switch, the voltage is compared with a reference voltage fVr1, and the abnormality is decided when the reference voltage is exceeded by the voltage to output an abnormality detection signal S1. That is, an excess level is outputted from the speaker 1 being the actuator, and the amplitude of the vibration in the diaphragm becomes large, and the abnormality is detected. Then, the formation of the cancel sound is interrupted according to the detection of the abnormality.
CHIKAISHI KOICHI
KAGEYAMA YOSHIHIRO
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