Specifying intonation in a text-to-speech system using only a small dictionary

In automatic synthesis of speech from English text, the quality of the output speech is highly dependent upon realistic intonation patterns. Most synthesizers have difficulty obtaining sufficient linguistic information from an input text to specify intonation properly. The syntactic structure of the text often specifies where a speaker should pause and which words to stress. However, the problem of parsing natural English is as yet unsolved. The problem is further complicated in systems which may wish to limit memory space and access time by minimizing dictionary size. In most other references, the parsing problem is only mentioned in passing, or parsing occurs on a local basis, ignoring important syntactic structures that encompass the entire sentence. The system described here recognizes function words and uses a set of syntactic constraints to estimate which words are likely to form phrases. This paper is the first to report on parsing details specifically for synthesis, while using only a small dictionary (of about 300 words).