An active noise control system comprising: a processor; and a memory connected to the processor, where the processor is configured to: generate an output signal from an infinite impulse response filter based on an input signal representative of an undesired sound; generate an anti-noise signal based on the output signal of the infinite impulse response filter, where the anti-noise signal is configured to drive a speaker to produce sound waves to destructively interfere with an undesired sound; generate an update signal based on the output signal of the infinite impulse response filter and an error signal representative of sound waves produced from a combination of the undesired sound and the sound waves produced by the speaker; and update a plurality of coefficients of the infinite impulse response filter based on the update signal; characterized in that the processor is further configured to: determine a plurality of update coefficients, each of the update coefficients corresponding to a respective one of the plurality of coefficients of the infinite impulse response filter; determine the stability of each of the update coefficients; and replace each of the plurality of coefficients of the infinite impulse response filter with corresponding update coefficients when each of the plurality of update coefficients is determined to be stable. a processor; and a memory connected to the processor, where the processor is configured to: generate an output signal from an infinite impulse response filter based on an input signal representative of an undesired sound; generate an anti-noise signal based on the output signal of the infinite impulse response filter, where the anti-noise signal is configured to drive a speaker to produce sound waves to destructively interfere with an undesired sound; generate an update signal based on the output signal of the infinite impulse response filter and an error signal representative of sound waves produced from a combination of the undesired sound and the sound waves produced by the speaker; and update a plurality of coefficients of the infinite impulse response filter based on the update signal; characterized in that the processor is further configured to: determine a plurality of update coefficients, each of the update coefficients corresponding to a respective one of the plurality of coefficients of the infinite impulse response filter; determine the stability of each of the update coefficients; and replace each of the plurality of coefficients of the infinite impulse response filter with corresponding update coefficients when each of the plurality of update coefficients is determined to be stable. generate an output signal from an infinite impulse response filter based on an input signal representative of an undesired sound; generate an anti-noise signal based on the output signal of the infinite impulse response filter, where the anti-noise signal is configured to drive a speaker to produce sound waves to destructively interfere with an undesired sound; generate an update signal based on the output signal of the infinite impulse response filter and an error signal representative of sound waves produced from a combination of the undesired sound and the sound waves produced by the speaker; and update a plurality of coefficients of the infinite impulse response filter based on the update signal; characterized in that the processor is further configured to: determine a plurality of update coefficients, each of the update coefficients corresponding to a respective one of the plurality of coefficients of the infinite impulse response filter; determine the stability of each of the update coefficients; and replace each of the plurality of coefficients of the infinite impulse response filter with corresponding update coefficients when each of the plurality of update coefficients is determined to be stable. determine a plurality of update coefficients, each of the update coefficients corresponding to a respective one of the plurality of coefficients of the infinite impulse response filter; determine the stability of each of the update coefficients; and replace each of the plurality of coefficients of the infinite impulse response filter with corresponding update coefficients when each of the plurality of update coefficients is determined to be stable.