Factors Affecting the Occurrence and Duration of Sentence-medial Pauses in Japanese Text Reading

Pauses play important roles for the intelligibility and naturalness of speech. Their occurrence and duration in text reading are influenced by syntactic structures of the text as well as by physiological constraints of respiration on the part of the speaker. In contrast to sentenceand paragraph-final pauses, sentence-medial pauses are influenced by a number of factors. Analysis of Japanese news text reading and of the syntactic structures of the text indicated that the main factors are: phrase type, phrase length, and distance between the current phrase and its dependent counterpart. Experimental formulae were derived both for the rate of occurrence and for the duration of a pause at a syntactic boundary, to serve as rules for pause insertion in text-to-speech synthesis. The results of prediction by these rules were in good agreement with the pauses actually observed in the speech material studied.