Research on a speech synthesis system for Japanese texts based on the natural language understanding

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The aim of this project is to construct a system which converts a Japanese text of orthographic symbols into connected speech with pronunciation of the standard Japanese.The main results obtained are as follows:(1) A method was developed which conducts syntactic and semantic analysis of weatherforecast sentences and transforms the results into a form appropriate for the speech synthesis.(2) Characteristics of fundamental frequency contours of announcements were analyzed quantitatively by using the model for fundamental frequency contour generation with special emphasis on the relationship between the syntactic structure of a sentence and the phrase component of a fundamental frequency contour.(3) Based on the analysis of the accent component in connected speech, relationships were quantitatively clarified between the accent components and the accent type of a word, the syntactic structure of a sentence and the discourse structure of a text.(4) The results in (1) to (3) were combined to … More construct rules for generation of prosodic symbols which are not explicitly represented in the text. These rules generate the symbols using the punctuation marks, the accent type of a word, the syntactic structure of a sentence and the discourse structure of a text.(5) The quality of the stored templates of syllables was improved based on the results of a listening test.(6) Investigations were made on the method for concatenating ARMA parameters of the stored syllable templates. The subjective evaluation was conducted for the synthesized speech.(7) Based on the above-mentioned results and those obtained in the preceding year, a system for speech synthesis of Japanese texts was developed. In this system, the segmental features are synthesized by concatenating stored syllable templates, while the prosodic features are synthesized by rule using the model for fundamental frequency contour generation. The validity of the system was proved by the listening tests of synthesized speech of Japanese texts. While this system was originally aimed at the weatherforecast sentences, it was also valid for sentences of other fields.The above results indicate that the project was almost fully accomplished. Less