ACTIVE NOISE REDUCTION DEVICE AND ACTIVE NOISE REDUCTION METHOD

An active noise reduction device includes: an impulsive signal generator that generates an impulsive signal; a signal output unit that outputs the impulsive signal to a loudspeaker; a signal detector that detects a rising signal and a falling signal from a microphone signal outputted from a microphone collecting sound; a connection determiner that determines, based on respective peak values of the rising signal detected and the falling signal detected, whether or not the loudspeaker is connected to the signal output unit; and a polarity determiner that determines a connection polarity between the loudspeaker and the signal output unit based on respective timings of the rising signal and the falling signal with respect to the impulsive signal, when it is determined that the loudspeaker is connected to the signal output unit.