Patent ID: 8010354

Claim:
A noise cancellation system for canceling a noise component relating to reproduced sound of an audio system from a speech signal input from a microphone, provided with: a noise cancellation signal generation unit for each channel for generating a noise cancellation signal for removing said noise component based on the audio signal of each channel acquired from an audio system for reproducing multiple channels of sound, an output unit for using each noise cancellation signal to remove a noise component included in a speech signal input from said microphone and outputting a noise-less speech signal, and a conversion unit for nonlinearly converting said noise-less speech signal, each noise cancellation signal generation unit provided with: a filter element for filtering said audio signal acquired from said audio system in accordance with a preset filter coefficient so as to generate a noise cancellation signal and a coefficient updating element for updating said filter coefficient set in said filter element based on said noise-less speech signal nonlinearly converted by said conversion unit and said audio signal, wherein said filter element processes a preset filter coefficient W[k] and an audio signal X(t) by convolutional processing in accordance with the following equation: C ⁡ ( t ) = ∑ k = 1 K ⁢ W ⁡ [ k ] · X ⁡ ( t - k ) so as to filter said audio signal X(t) and generate said noise cancellation signal C(t), said conversion unit enters a noise-less speech signal U(t) which said noise-less speech signal output unit outputs into a nonlinear function f(x) to generate a converted noise-less speech signal f(U(t)) after said nonlinear conversion, and said coefficient updating element calculates a filter coefficient F[k] based on said converted noise-less speech signal f(U(t)), said audio signal X(t), and said filter coefficient W[k] in accordance with the following equation including preset constants α and β: F ⁡ [ k ] = W ⁡ [ k ] - α · f ⁡ ( U ⁡ ( t ) ) · X ⁡ ( t - k ) norm + β norm = 1 K · ∑ k = 1 K ⁢  X ⁡ ( t - k )  where, the constant K is a tap number of a whole number of 2 or more, and the variable t is a variable indicating time and a whole value and setting this filter coefficient F[k] in said filter element so as to update said filter coefficient W[k].