Active noise control device, active noise control method, and active noise control program

An active noise control method comprising:

• preparing an adaptive filter that generates a control signal by performing signal processing on a reference signal generated based on a vibration frequency generated by a vibration source, and sequentially updating the adaptive filter based on a signal input from a microphone when the control signal is output from a speaker, the active noise control method comprising the steps of:
• acquiring an acoustic characteristic including amplitude and phase information, the acoustic characteristic being an acoustic characteristic of a secondary path between the speaker and the microphone, and calculating an amplitude characteristic of the secondary path having a different value according to a frequency based on the acquired acoustic characteristic;
• smoothing the amplitude characteristic using a low-pass filter and generating a smoothed signal having a different value according to a frequency;
• calculating a correction coefficient having a different value according to a frequency based on a result of dividing the amplitude characteristic by the smoothed signal;
• updating the adaptive filter by subtracting an update term including the correction coefficient from a first adaptive filter coefficient that is an immediately preceding adaptive filter coefficient to obtain a second adaptive filter coefficient;
• and
• generating the control signal by multiplying the reference signal by the second adaptive filter coefficient.

A non-transitory computer readable medium storing a program that causes a computer of an active noise control to control a noise using an adaptive filter that generates a control signal by performing signal processing on a reference signal generated based on a vibration frequency generated by a vibration source, and sequentially updating the adaptive filter based on a signal input from a microphone when the control signal is output from a speaker, the computer executing the steps of:

• acquiring an acoustic characteristic including amplitude and phase information, the acoustic characteristic being an acoustic characteristic of a secondary path between the speaker and the microphone, and calculating an amplitude characteristic of the secondary path having a different value according to a frequency based on the acquired acoustic characteristic;
• smoothing the amplitude characteristic using a low-pass filter and generating a smoothed signal having a different value according to a frequency;
• calculating a correction coefficient having a different value according to a frequency based on a result of dividing the amplitude characteristic by the smoothed signal;
• updating the adaptive filter by subtracting an update term including the correction coefficient from a first adaptive filter coefficient that is an immediately preceding adaptive filter coefficient to obtain a second adaptive filter coefficient;
• and
• generating the control signal by multiplying the reference signal by the second adaptive filter coefficient.