Noise control system

A noise control system, comprising:

• a control sound generator for generating a control sound;
• an error detector for detecting an error signal between the control sound and noise;
• a noise detector for detecting a noise source signal;
• an adaptive filter for outputting a control signal;
• a coefficient updator for updating a coefficient of the adaptive filter, the coefficient updator comprising at least a first digital filter, a first coefficient update calculator, a second digital filter, a phase inverter, a third digital filter, and a second coefficient update calculator;
• the first digital filter approximates a propagation characteristic between the control sound generator and the error detector;
• the second and third digital filters have a common passband frequency characteristic,
• the second coefficient update calculator receives, as inputs thereto, processed outputs from the second and third digital filers;
• wherein the coefficient updator has a function of suppressing an increase in a coefficient gain of the adaptive filter in a predetermined frequency band.