This paper describes the development and evaluation of the grapheme-to-phoneme sub-system of a complete real-time synthesis system under development at Macquarie University. It has been developed around a lexicon knowledge base which contains the 4000-5000 most common English words and which has been augmented by a suffix stripper and a set of grapheme to phoneme rules. Evaluation and development of this system has been facilitated by using weighted statistics which reflect the frequency of occurence of each word in the LOB and Brown corpora of English. These statistics are derived from a test word database which includes all acceptable Australian pronunciations (as defined by the Macquarie Dictionary) of each word, as well as their LOB and Brown frequency counts. The pronunciation derived by the system is compared to the Macquarie Dictionary pronunciations and given a score proportional to its frequency in the two corpora. These scores facilitate decisions to be made about which alterations to the rules or lexicon will have the greatest effect on total system accuracy in ordinary running text (as reflected by the corpora frequencies).
- letter-to-sound rules