A phonetically labeled acoustic segment (PLAS) approach to speech analysis-synthesis

A phonetically labeled acoustic segment (PLAS) approach is proposed for speech analysis-synthesis. The goal is to develop a unified framework for general speech processing by means of a bidirectional context-constrained mapping between a phonetic space and an acoustic space. The PLAS analysis module is a continuous phone (phoneme) recognizer, while the PLAS synthesis module is a phonetically organized acoustic database. To regulate the proposed mapping in a phonetically structured manner, phone context-dependency was imposed in phone modeling, recognition, and synthesis. The PLAS approach was tested successfully on a database of continuously spoken Japanese utterances recorded by a single male talker. The automatic segmentation boundaries derived from modeling PLAS units agreed well with corresponding manual segmentation points, i.e. they were within a +or-20-ms interval 95% of the time. A 4% phoneme recognition error rate was obtained in a continuous recognition test. Natural-sounding speech was synthesized at an average bit rate of 55 b/s allocated to segmental information.>