1. A voice recognition system for comparing an uttered voice including a multiplicative distortion and an additive noise with a combined model obtained by combining a noise model with an acoustic model formed based on a voice including at least a multiplicative distortion to perform voice recognition, the voice recognition system comprising; a first extracting section for extracting a feature component of the multiplicative distortion included in the uttered voice; a second extracting section for extracting a feature component of a multiplicative distortion included in the acoustic model; a first calculating section for combining the uttered voice with the feature component of the multiplicative distortion extracted by the first extracting section; a second calculating section for combining the acoustic model with the feature component of the multiplicative distortion extracted by the second extracting section; a third calculating section for combining the noise model with the feature component of the multiplicative distortion extracted by the first extracting section; and a forming section for combining a result of the calculation by the second calculating section with a result of the calculation by the third calculating section to form the combined model, and wherein voice recognition is performed by comparing a result of the calculation by the first calculating section with the combined model.