Using phase spectrum information for improved speech recognition performance

New acoustic features for continuous speech recognition based on the short-term Fourier phase spectrum are introduced for mono (telephone) recordings. The new phase based features were combined with standard Mel Frequency Cepstral Coefficients (MFCC), and results were produced with and without using additional linear discriminant analysis (LDA) to choose the most relevant features. Experiments were performed on the SieTill corpus for telephone line recorded German digit strings. Using LDA to combine purely phase based features with MFCCs, we obtained improvements in word error rate of up to 25% relative to using MFCCs alone with the same overall number of parameters in the system