Automatic recognition of voiced stop consonants in CV and VCV utterances

A method is described for the accurate extraction of formant trajectories from utterances containing voiced stop consonants, and for the determination of the formant loci from the trajectories. Analysis of CV and VCV utterances revealed that the loci of the second, third and fourth formants are dependent on the vowel following the consonant, but can provide sufficient information for the separation of [b], [d], and [g] in most cases. The rise time constant of the short-time power is found to supplement formant loci information in cases where the latter is not sufficient. It is shown that correct recognition of the three voiced stop consonants from a single speaker is possible by first identifying the following vowel and by using a set of context-dependent linear discriminant functions in a 4-dimensional space of the three formant loci and the rise time constant.