Mixed Excitation Linear Prediction Model Research Articles

Research on an Embedded Ultra-Low-Bit-Rate Speech Coding Algorithm

Ultra-low-bit-rate speech coding algorithm was in great demand for many fields such as underwater speech communications. Underwater speech communication for middle-long distance has the characteristics of narrow bandwidth as well as low transmission rate, which makes the underwater speech communication much difficult. Ultra-low-bit-rate speech coding algorithm plays an important role on this occasion. More over, it will be more flexible for the underwater speech communication system if the speech coding algorithm has an embedded structure. The paper introduced the principle of an embedded speech coding algorithm with dual rates at both 300bps and 400bps based on the enhanced mixed excitation linear prediction model. The results show that this embedded ultra-low-bit-rate speech coding algorithm has satisfactory quality under both DRT and MOS test.

Reconstruction of speech from whispers

This paper investigates a method for the real-time reconstruction of normal speech from whispers. This system could be used by aphonic individuals as a voice prosthesis. It could also provide improved verbal communication when normal speech is not appropriate. The normal speech is synthesized using the mixed excitation linear prediction model. Differences between whispered and phonated speech are discussed and methods for estimating the parameters of this model from whispered speech for real-time synthesis are proposed. This includes smoothing the noisy linear prediction spectra, modifying the formants, and synthesizing of the excitation signal. Trade-offs between computational complexity, delay, and accuracy of different methods are discussed.