Speech nonlinearities, modulations, and energy operators
ICASSP '91 Proceedings of the Acoustics, Speech, and Signal Processing, 1991. ICASSP-91., 1991 International Conference
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Recent work has verified that the second-formant frequency (F2) and its change in the vowel immediately preceding a stop consonant are usually sufficient to discriminate between labial, palatal, and alveolar stops, even in the absence of the stop burst information. Informal listening tests using truncated samples indicate that humans can discriminate the three stops on the basis of the preceding vowel alone. Typical quasi-stationary analyses like LPC and DFT filterbanks may not have sufficient time-frequency resolution to detect the rapid F2 variations, and therefore a valuable source of stop classification information is being overlooked. This paper shows the results of using the DESA-1 quadratic frequency estimator to determine the frequency and rate of change of F2. It is shown for different vowel environments that the DESA-1 algorithm can extract sufficient information to classify stops from vocalic data. The performance is demonstrated to be superior to a formant tracker using a more conventional pitch-synchronous LPC analysis.