Cues for question intonation in Arabic: Disambiguation techniques for use in automatic speech recognizer systems

Abstract

The focus of this study is to determine the extent to which prosodic characteristics can contribute to the improvement of speech recognition in Arabic. F0 rising rate was chosen to disambiguate yes–no question from declarative sentences. In Arabic, as in English, a rising intonation indicates a yes–no question whether the question takes lexical question markers or uses an inverted word order or whether the sentence takes just a declarative form. We conducted a production study with 55 yes–no question sentences uttered by a female native speaker of Arabic. Two types of measurements were taken for F0 rise rate. First, we visually obtained the best-fit rise in sentence-final position. Second, we computed the rate based on minimum and maximum F0 values within the sentence-final 500 ms. The results show that although the rise obtained from the final 500 ms (0.41 Hz/ms) is different from the best-fit rise rate (0.49 Hz/ms) (p<0.05), when examining two different F0 rising shapes and considering JND for the rising rate (Nabelek and Hirsh, 1962), a threshold of 0.4 Hz/ms can be considered a threshold indicator of a yes–no question intonation for this speaker. Thus, a sufficient rise rate was extracted automatically from a fixed sentence-final duration.