A study on a reduction of the transmission bit rate by U/V decision using LSP in the CELP vocoder

Author

Lee, Yoonjoo ; Ham, MyungKyu ; Bae, MyungJin

Author_Institution

Dept. of Inf. & Telecommun. Eng., Soongsil Univ., Seoul, South Korea

Volume

2

fYear

1999

fDate

1999

Firstpage

997

Abstract

In a typical CELP vocoder, the unvoiced speech is processed like the voiced speech. Hence the speech quality is degraded. Also, the degree of the speech quality degradation is excessive depends on the performance of the U/V classifier. In this paper, we propose a new U/V (Unvoiced/Voiced) decision algorithm with minimized error rate and preprocessing computation. This U/V classifier uses the LSP (Line Spectrum Pair) parameter, which is acquired from the spectrum analysis process in CELP vocoders. Applying this method to the 5.3 kbps ACELP, we can achieve a transmission bit rate reduction of 5.6% (280 bps) approximately. By applying the synthesis speech quality in the G.723.1 and the proposed method to the MOS (Mean Opinion Score) test the former gets average MOS 3.77 and the latter does 3.75

Keywords

linear predictive coding; speech coding; vocoders; 5.3 kbit/s; ACELP; CELP vocoder; G.723.1 type; LSP; U/V decision; code excited linear prediction; line spectrum pair parameter; minimized error rate; preprocessing computation; spectrum analysis process; speech quality degradation; transmission bit rate reduction; unvoiced/voiced decision algorithm; Bit rate; Degradation; Error analysis; Filters; Linear predictive coding; Propagation losses; Speech processing; Speech synthesis; Testing; Vocoders;

fLanguage

English

Publisher

ieee

Conference_Titel

Circuits and Systems, 1999. 42nd Midwest Symposium on

Conference_Location

Las Cruces, NM

Print_ISBN

0-7803-5491-5

Type

conf

DOI

10.1109/MWSCAS.1999.867803

Filename

867803