1. A method of adapting a speech recognition system to speech data provided to the speech recognition system, the method comprising the steps of: computing alignment information between the speech recognition system and feature vectors associated with the speech data provided to the speech recognition system; computing an original spectra for each feature vector and corresponding mean vector; estimating one or more transformation parameters which maximize a likelihood of an utterance; and transforming a current feature vector using the estimated transformation parameters and maximum likelihood criteria, the transformation being performed in a linear spectral domain.