Unit selection synthesis 1 -a technique which concatenates segments of natural speech selected from a database-has been found to be capable of producing high quality synthetic speech, especially for utterances that are similar to the speech in the database in terms of style, delivery, and coverage (Black and Lenzo, 2001).
in the limited domain of a spoken language dialogue system, it is possible to achieve highly natural synthesis with a purpose-built voice (Black and Lenzo, 2000).