On the importance of various modulation frequencies for speech recognition

Temporal processing of the time trajectories in the logarithmic spectrum domain, performed in cepstral mean subtraction, in computation of dynamic features in speech, or in RASTA processing, is becoming a common procedure in current ASR. Such temporal processing effectively enhances some components of the modulation spectrum of speech while suppressing others. It is therefore important to know the relative importance of various components of the modulation spectrum of speech. In this study we report on the e ect of band-pass ltering of the time trajectories of spectral envelopes on speech recognition. Results indicate the relative importance of di erent components of the modulation spectrum of speech for ASR.