Abstract: An active noise control apparatus includes a control frequency detector for determining a control frequency which is a frequency of a noise to be controlled, a sine-wave generator for generating a reference sine-wave signal having the determined control frequency, a cosine-wave generator for generating a reference cosine-wave signal having the determined control frequency, a first one-tap digital filter for outputting a first control signal obtained by multiplying the reference sine-wave signal by a first filter coefficient, a second one-tap digital filter for outputting a second control signal obtained by multiplying the reference cosine-wave signal by a second filter coefficient, an interference signal generator for generating an interference signal based on a noise control signal obtained by summing the first control signal and the second control signal, an error signal detector for detecting an error signal produced due to an interference between the interference signal and the noise, first and second coe

Abstract: In an active noise reduction apparatus with an adaptive notch filter used, a triangle wave as a reference signal input into a first coefficient updater and a second coefficient updater reduces the number of execution times of product-sum operations in a reference signal generator to reduce the operation load.