Some Prosodic Details of American English

Abstract

General principles for prosodic rules for English, reported previously [C. Coker and N. Umeda, “Acoustical Properties of Word Boundaries in English; On the Vowel Duration and Pitch Prominence,” J. Acoust. Soc. Amer. 47, 94 (1969)] are now implemented in a computer program. Surprisingly, the rules depend mainly on the surface structure of the sentence and on properties of the words. To provide better prosidic features for automatic synthesis, however, additional rules have been added. A good measure of the difficulty of speech material is found to be the proportion of content words to function words. According to this ratio, stress and pause assignment should be different. A paragraph redundancy rule, promoting first occurrences of content words and demoting subsequent repetitions, is found to improve naturalness and reduce monotony of the synthetic speech. Several special verb classes are assumed for assignment of clause, phrase, and word boundaries. These verbs, although different from auxiliary verbs, behave like auxiliaries in the sense that the main idea is conveyed by the remainder of the predicate. Stress and boundary assignment are altered according to verb class. Local phonetic interactions require adjustments in durations of phonemes according to specific contexts. Details of these rules and examples from synthesis are presented.