a mode selector for selecting between normal mode and measurement mode;

a frequency detector for detecting a frequency of vibrational noise generated from a vibrational noise source based on the normal mode selected by the mode selector;

a pseudo-vibrational noise generator for outputting a signal in a predetermined frequency range corresponding to the frequency of the vibrational noise generated from the vibrational noise source, based on the measurement mode selected by the mode selector;

a first switch for selecting between the output signal of the pseudo-vibrational noise generator and an output signal of the frequency detector, and outputting the output signal selected;

a reference cosine wave generator and a reference sine wave generator for receiving the output signal of the first switch;

a first adaptive notch filter for outputting a first control signal based on the reference cosine wave signal outputted from the reference cosine wave generator in order to cancel the vibrational noise generated, based on the vibrational noise from the vibrational noise source;

a second adaptive notch filter for outputting a second control signal based on the reference sine wave signal outputted from the reference sine wave generator;

a first adder for receiving the first control signal and the second control signal;

a second switch for receiving a signal outputted from the first adder;

a third switch for receiving one of the reference cosine wave signal and the reference sine wave signal;

a vibrational noise canceller for canceling the vibrational noise generated, the vibrational noise canceller receiving an output of the second switch and an output of the third switch;

an error signal detector for outputting an error signal resulting from interference between the vibrational noise generated and a noise-canceling sound outputted from the vibrational noise canceller;

a fourth switch for receiving the output of the first adder;

a second adder for receiving an output of the fourth switch and the output of the error signal detector;

a fifth switch for receiving the reference cosine wave signal;

a sixth switch for receiving the reference sine wave signal;

a first filter coefficient updater for calculating a filter coefficient of the first adaptive notch filter based on an output signal of the second adder and an output signal of the fifth switch so as to minimize the output signal of the second adder, and for updating the filter coefficient sequentially;

a second filter coefficient updater for calculating a filter coefficient of the second adaptive notch filter based on the output signal of the second adder and an output signal of the sixth switch so as to minimize the output signal of the second adder, and for updating the filter coefficient sequentially;

a correction value calculator for receiving the filter coefficients of the first and second filter coefficient updaters, the correction value calculator being able to calculate at least a phase characteristic value out of a gain characteristic value and the phase characteristic value of signal transmission characteristics from the vibrational noise canceller to the error signal detector, corresponding to a frequency of one of the reference cosine wave signal and the reference sine wave signal, and also being able to calculate a cosine correction value and a sine correction value; and

a corrector for correcting the reference cosine wave signal and the reference sine wave signal by using the cosine correction value and the sine correction value, respectively, and outputting a corrected cosine wave signal and a corrected sine wave signal to the fifth switch and the sixth switch, respectively, wherein

the corrector comprises:

a memory for storing the cosine correction value and the sine correction value;

a first multiplier for forming a product of the cosine correction value and the reference cosine wave signal;

a second multiplier for forming a product of the sine correction value and the reference sine wave signal;

a third multiplier for forming a product of the cosine correction value and the reference sine wave signal;

a fourth multiplier for forming a product of the sine correction value and the reference cosine wave signal;

a third adder for receiving an output signal of the first multiplier and an output signal of the second multiplier separately, and outputting the corrected cosine wave signal; and

a fourth adder for receiving an output of the third multiplier and an output of the fourth multiplier separately, and outputting the corrected sine wave signal.