Patent ID: 7089182

Claim:
A method for performing noise adaptation of a target speech signal input to a speech recognition system, said target speech signal containing both additive and convolutional noises, said method comprising: estimating an additive noise bias and a convolutional noise bias in said target speech signal; and jointly compensating the target speech signal for the additive and convolutional noise biases in a feature domain, wherein said target speech signal comprises a plurality of frames, and further wherein said estimating a convolutional noise bias comprises: determining a speech signal partially adapted to the test environment in additive noise; and utilizing the partially adapted speech signal to estimate the convolutional noise bias, and wherein said determining a speech signal partially adapted to the test environment in additive noise comprises determining a first order approximation as: C ⁡ ( H tar · S + N ref ) = C ⁡ ( H tar · S + N tar ) + ∂ C ⁡ ( H tar · S + N ) ∂ N  N = N tar ⁢ ( N ref - N tar ) , = C ⁡ ( H tar · S + N tar ) + J N ⁢ Δ ⁢ ⁢ N , wherein: C(·) is the cepstral operator; H tar is a channel frequency response for a test environment; N ref is an additive noise for a training environment; N tar is an additive noise for the test environment; S represents a clean version of the target speech signal; J N ⁢ ⁢ is ⁢ ⁢ ∂ C ⁡ ( H tar · S + N ) ∂ N  N = N tar , a ⁢ ⁢ noise ⁢ ⁢ compensation ⁢ ⁢ matrix ; ΔN is (N ref −N tar ); and C(H tar ·S+N ref ) is said partially adapted speech signal.