Details of the Nitech HMM-Based Speech Synthesis System for the Blizzard Challenge 2005

Heiga ZEN  Tomoki TODA  Masaru NAKAMURA  Keiichi TOKUDA  

IEICE TRANSACTIONS on Information and Systems   Vol.E90-D   No.1   pp.325-333
Publication Date: 2007/01/01
Online ISSN: 1745-1361
Print ISSN: 0916-8532
Type of Manuscript: PAPER
Category: Speech and Hearing
HMM-based speech synthesis,  Blizzard Challenge 2005,  STRAIGHT,  HSMM,  GV,  

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In January 2005, an open evaluation of corpus-based text-to-speech synthesis systems using common speech datasets, named Blizzard Challenge 2005, was conducted. Nitech group participated in this challenge, entering an HMM-based speech synthesis system called Nitech-HTS 2005. This paper describes the technical details, building processes, and performance of our system. We first give an overview of the basic HMM-based speech synthesis system, and then describe new features integrated into Nitech-HTS 2005 such as STRAIGHT-based vocoding, HSMM-based acoustic modeling, and a speech parameter generation algorithm considering GV. Constructed Nitech-HTS 2005 voices can generate speech waveforms at 0.3RT (real-time ratio) on a 1.6 GHz Pentium 4 machine, and footprints of these voices are less than 2 Mbytes. Subjective listening tests showed that the naturalness and intelligibility of the Nitech-HTS 2005 voices were much better than expected.