Independent calculation of power parameters on PMC method

To achieve robust speech recognition in noise, noise compensation techniques is necessary. The effectiveness of the parallel model combination technique (PMC) due to Gales (see Speech Communication, vo1.22, no.3, p.231-9, 1993) has been reported earlier. However, we found that the noise compensation mechanism using the basic PMC method didn´t work well on the power parameters. We first show that there is a mismatch in the power parameters in the PMC method. Then, we propose a new method called IPPMC which calculates the power parameters independently of the other cepstral parameters. Finally we evaluate the IPPMC through the investigation of spectral envelopes, the comparison of the model distances to the target HMM trained by noisy speech and the experiment of the speaker-independent continuous speech recognition. The IPPMC improved the word accuracy from 82.1% obtained by the PMC to 85.5% at 10 dB SNR