Signal processing device, signal processing method and signal processing program for noise cancellation

A noise cancelling method comprising:

• generating a replica of said noise signal which is mixed with a desired signal in a first mixed signal by filtering a second mixed signal in which said desired signal and said noise signal are mixed in a different proportion from said first mixed signal, using a set of coefficients-of a first adaptive filter updated by a first control signal;
• generating an estimated desired signal by subtracting said replica of said noise signal from said first mixed signal;
• and
• generating said first control signal to make an update amount of said set of coefficients smaller as compared with an opposite case when a power of said estimated desired signal is larger than a power of said first mixed signal.

A non-transitory computer readable storage medium recording thereon a noise cancelling program causing a computer to execute a method comprising:

• generating a replica of said noise signal which is mixed with a desired signal in a first mixed signal by filtering a second mixed signal in which said desired signal and said noise signal are mixed in a different proportion from said first mixed signal, using a set of coefficients-of a first adaptive filter updated by a first control signal;
• generating an estimated desired signal by subtracting said replica of said noise signal from said first mixed signal;
• and
• generating said first control signal to make an update amount of said set of coefficients smaller as compared with an opposite case when a power of said estimated desired signal is larger than a power of said first mixed signal.

A noise cancelling device comprising:

• first sensor means for obtaining a first mixed signal in which a desired signal and a noise signal are mixed;
• second sensor means for obtaining a second mixed signal in which said desired signal and said noise signal are mixed in a different proportion from said first mixed signal;
• first subtractor means for generating an estimated desired signal by subtracting a replica of a noise signal from said first mixed signal;
• first adaptive filter means for generating said replica of said noise signal by filtering said second mixed signal using a first set of coefficients-updated by a first control signal;
• first comparator means for comparing a power of said estimated desired signal and a power of said first mixed signal;
• and
• first controller means for generating said first control signal to make an update amount of said first set of coefficients smaller as compared with an opposite case when a power of said estimated desired signal is larger than a power of said first mixed signal as a result of comparison by said first comparator means.

An echo cancelling device comprising:

• a first sensor which inputs a first mixed signal in which a near-end signal and an echo signal are mixed;
• a first input terminal which inputs a reference signal which is correlated with said echo signal;
• a first subtractor which generates an estimated near-end signal by subtracting a replica of said echo signal from said first mixed signal;
• a first adaptive filter which generates said replica of said echo signal by filtering said reference signal using a first set of coefficients updated by a first control signal;
• a first comparator which compares a power of said estimated near-end signal and a power of said first mixed signal;
• and
• a first controller which generates said first control signal to make an update amount of said first set of coefficients smaller as compared with an opposite case when a power of said estimated near-end signal is larger than a power of said first mixed signal as a result of comparison by said first comparator.