Formant estimation of whispered speech based on pole interaction

Comparing with normal speech, the formant of whisper is shifted and the bandwidth is broadened since the transfer function of whisper varies with subjoining pole points that bring up the pole interaction problem. The change of bandwidth will lead to the result that one or more real roots are regarded as spurious root and deleted from the original LP polynomial. To reduce the degradation of pole interaction, an improved root-finding formant estimation algorithm has been proposed. In this algorithm, the whisper formant bandwidth is modified to make the spectral energy of the remained formant polynomial to be equal to that of the original LP polynomial. Experimental results with mono-vowel phones in Mandarin speech prove the algorithm can abstract whisper formant exactly.