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

An active noise control method, comprising:

• multiplying a reference signal by m, where m is a positive number, the reference signal being output from a reference signal source and having a correlation with noise;
• compressing an amplitude of the reference signal multiplied by m within a threshold so that clipping of the reference signal multiplied by m is suppressed, the reference signal multiplied by m having the amplitude greater than or equal to the threshold;
• outputting a compressed signal of the reference signal multiplied by m;
• multiplying the compressed signal by n, where n is a positive number;
• generating a canceling signal having a phase opposite to a phase of the compressed signal multiplied by n by multiplying the compressed signal multiplied by n output in the multiplying using an adaptive filter, the adaptive filter having a coefficient that is updated successively;
• updating the coefficient of the adaptive filter using a step size parameter, the step size parameter determining an amount of updating the coefficient of the adaptive filter based on a change in the amplitude of the reference signal;
• multiplying the reference signal, that is not yet multiplied by m, by m×n, and
• adjusting the step size parameter using the reference signal multiplied by m×n.

An active noise control device, comprising:

• a processor;
• and
• a memory including a control program that, when executed by the processor, causes the processor to perform operations, the operations including:
• receiving a reference signal output from a reference signal source, the reference signal having a correlation with noise;
• multiplying the reference signal by m, where m is a positive number, the reference signal multiplied by m having an amplitude greater than or equal to a threshold;
• compressing the amplitude of the reference signal multiplied by m within the threshold so that clipping of the reference signal multiplied by m is suppressed;
• outputting a compressed signal of the reference signal multiplied by m;
• multiplying the compressed signal by n, where n is a positive number;
• generating a canceling signal having a phase opposite to a phase of the compressed signal by multiplying the compressed signal multiplied by n using an adaptive filter, the adaptive filter having a coefficient that is updated successively;
• updating the coefficient of the adaptive filter using a step size parameter, the step size parameter determining an amount of updating the coefficient of the adaptive filter based on a change in the amplitude of the reference signal;
• multiplying the reference signal, that is not yet multiplied by m, by m×n;
• and
• adjusting the step size parameter using the reference signal multiplied by m×n.