Design and development of a very low bit rate Phonetic vocoder for Farsi Language

Author

Homayounpour, M.M. ; Koochari, A. ; Moaddab, H.R.S.

Author_Institution

Dept. of Comput. Eng. & Inf. Technol., Amirkabir Univ. of Technol., Tehran

Volume

1

fYear

0

fDate

0-0 0

Firstpage

1225

Lastpage

1229

Abstract

This paper presents a very low bit rate (VLBR) speech vocoder for Farsi language. Vocoder encoder consists of a phoneme recognizer, voiced/unvoiced, pitch and gain estimators. Phoneme index, state durations, pitch and gain are quantized, encoded and transmitted to decoder. In the decoder, phoneme HMMs are concatenated according to the phoneme indexes, and a sequence of MFCC coefficient vectors is generated from the concatenated HMMs by using an ML-based speech parameter generation technique. Finally we obtain synthetic speech by exciting the MLSA (mel log spectrum approximation) filter, whose coefficients are given by MFCC coefficients, according to the pitch information. A phoneme recognition rate of 77% and a total bit rate of 295 bits/s were obtained. Intelligibility and naturalness of synthesized speech was evaluated using MOS subjective tests. MOS intelligibility score was 2.7

Keywords

hidden Markov models; spectral analysis; speech coding; speech intelligibility; speech recognition; speech synthesis; vector quantisation; vocoders; Farsi language; decoder; gain estimator; gain quantization; hidden Markov model; mel log spectrum approximation filter; phoneme index; phoneme recognition rate; phoneme recognizer; pitch estimator; pitch information; pitch quantization; speech parameter generation; speech vocoder encoder; synthetic speech synthesis; very low bit rate phonetic vocoder; Bit rate; Concatenated codes; Decoding; Information filtering; Information filters; Mel frequency cepstral coefficient; Natural languages; Speech recognition; Speech synthesis; Vocoders; Hidden Markov Model; MLSA filter; phonetic vocoder; quantization; speech synthesis; very low bit rate vocoder;

fLanguage

English

Publisher

ieee

Conference_Titel

Information and Communication Technologies, 2006. ICTTA '06. 2nd

Conference_Location

Damascus

Print_ISBN

0-7803-9521-2

Type

conf

DOI

10.1109/ICTTA.2006.1684552

Filename

1684552