Active noise reduction system

An active noise reduction system, comprising:

• a canceling sound output device configured to output a canceling sound for canceling a noise;
• an error microphone configured to generate an error signal based on the noise and the canceling sound;
• and
• a controller configured to control the canceling sound output device based on the error signal,
• wherein the controller includes:
• a control signal generation unit including a control filter configured to generate a control signal for controlling the canceling sound output device;
• and
• a sound field learning unit including a secondary path filter that represents an estimation value of a transfer function of a secondary path from the canceling sound output device to the error microphone,
• the control filter and the secondary path filter are configured to be adaptively updated,
• the controller includes a plurality of control channels each including the control signal generation unit and the sound field learning unit, and
• the controller is configured to differentiate a timing of an adaptive update of the secondary path filter in each of the control channels.