400bps High-Quality Speech Coding Algorithm

Low bit rate speech coding is important to speech communications over band-limited or harsh channels. In this paper, based on the mixed excitation linear prediction (MELP) model, we propose a high-quality 400bps low bit rate speech coding algorithm which introduces multi-frame joint vector quantization, adaptive spectral enhancement and multi-band sinusoidal mixed excitation. Efficient parameter quantization schemes are employed on the basis of the super-frame structure. It is verified that the synthesized speech has fairly high intelligibility and naturalness, and the mean opinion score (MOS) is about 2.52.