Detection of vowel onset point events using excitation information

This paper proposes a method for the detection of Vowel Onset Point (VOP) events in speech using excitation information. VOP event is defined as the instant at which the onset of vowel takes place. For syllable-like units such as Consonant Vowel (CV) type, VOP event is the instant at which the consonant ends and the vowel begins. The speech signal is processed by the Linear Prediction (LP) analysis to extract the LP residual. The LP residual mostly contains the excitation information. The Hilbert envelope of the LP residual is derived using the analytic signal concept. A method is developed for detecting the VOP events using the Hilbert envelope of the LP residual and a modulated Gaussian window function. The performance of the proposed method is evaluated using reference VOP markings. The performance of the proposed method is also compared with the existing methods based on the vocal tract system features. The comparison shows that the excitation source also contains significant information about the VOP events.