Group Delay based Methods for Detection and Recognition of Whispered Speech

The present study demonstrates the effectiveness of the group delay function for detection and recognition of whispered speech. The group delay function in its spectral form is able to differentiate phonated from the whispered speech. In particular, the mean height-bandwidth product of the formants in the lower and mid frequency regions of the short term spectrum of speech is used herein for whisper speech detection. The mean height-bandwidth vector is obtained herein across all frames and is further smoothed using a moving average filter. The smoothed temporal version on this vector is able to detect the phonated to whisper change points. Towards this end, the current study investigates the cepstral, linear prediction (LP), minimum variance distortionless response (MVDR) and numerator of the group delay based smoothing techniques for whisper change point detection. Experiments on whispered speech detection are performed on the CHAINS database. Experimental results are compared to various methods for whispered speech detection available in literature.