Multi-Channel Active Noise Control System with Channel Equalization

A method of operating a multi-channel active noise cancellation comprising:

• operating a random noise generator to feed noise to at least two control sources;
• using at least two transducers to measure responses to the noise;
• forming an estimated secondary path transfer function matrix (SPTFM) [ŝ]KM based upon the transducer responses;
• taking a Fast Fourier Transform of the estimated SPTFM [ŝ]KM;
• calculating a mean magnitude of a main path of each column of the estimated SPTFM [Ŝ]KM;
• dividing each column of the estimated SPTFM [ŝ]KM by its respective main path mean magnitude;
• multiplying by a reference value to obtain a virtual SPTFM [se]KM;
• applying a filtered-x least mean squares algorithm with the virtual SPTFM [se]KM to update coefficients of an adaptive filter;
• generating a reference signal correlated with the undesired noises in a working environment;
• filtering the reference signal using the adaptive filter to produce a cancellation signal;
• using the cancellation signal to drive the sources to cancel noise associated with the reference signal in the working environment;
• and
• recursively adjusting the adaptive filter with the filtered reference signal.