Analysis-by-synthesis multimode harmonic speech coding at 4 kb/s

This paper presents a 4 kb/s analysis-by-synthesis multimode harmonic coder (AbS-MHC). Novel features of this coder include a signal modification technique that allows time-domain analysis-by-synthesis parameter estimation in a sinusoidal coding framework, and a frequency-domain transition speech model with improved parameter estimation and quantization schemes. An efficient quantization scheme for harmonic magnitudes based on weighted non-square transform vector quantization (WNSTVQ) is also used. Subjective quality tests indicate that the 4 kb/s AbS-MHC coder outperforms the 5.3 kb/s G.723.1 standard CELP coder and produces speech quality very similar to the 6.3 kb/s G.723.1 coder