Semi‐automatic labeling of pitch accents in American English

Abstract

This study provides a simple classification of several pitch accents that occur in American English, based on acoustic measurements of F0. Audio samples recorded by a female speaker and transcribed in the ToBI framework (Beckman, 1994) were used to develop five rules to recognize the pitch accents H*, L*, L+H*, and L*+H. Since no information about prosodic phrasing was given to the recognizer, some combinations with phrase accents were considered and contours then grouped into equivalent labels (e.g., %HL* equivalent to H*L−). Based on the rules developed, a semi−automatic process of labeling pitch accents was implemented in Praat. Half of the audio samples were used to train the labeler, the other half to test it. The accuracy level achieved was 69%. When effects of microprosody, creaky voice, or incorrect automatic pitch tracking were removed, the accuracy of classification into equivalent labels increased to 90%. Two types of applications are proposed: semi−automatic computer labeling of intonation for larger quantities of data, and a tool to help human transcribers learn American English ToBI using Praat. In addition, the simple classification is the first step towards looking into speaker variability in realization of different contours, and typology of intonational contours in different languages.