Significance of Vowel Onset Point for Speech Analysis

In this paper we discuss the significance of Vowel Onset Point (VOP) for speech recognition in particular, and for accurate speech analysis in general. Vowel onset point is the instant at which the vowel part starts in a ConsonantVowel (CV) utterance. The syllable-like CV utterances are basic units for both speech production and speech recognition. Recognition performance of isolated utterances of CV units improves significantly, if the parameters/features are extracted using VOPs as anchor points. Even manual identification of VOP requires acoustic cues specific to each subgroup of CV units. We present some acoustic cues which help in manual identification of VOPs in CV utterances. A database of CV units with VOPs marked, together with the knowledge of acoustic cues, will be useful to develop an algorithm for automatic detection of VOPs.