Variable rate speech coding using STRAIGHT and temporal decomposition

This paper presents a method for variable rate speech coding at an average rate around 1.8 kbps based on STRAIGHT, a high quality speech analysis-synthesis method. For encoding spectral information, limited error based event localizing temporal decomposition (LEBEL-TD) based vector quantization is used, where LEBEL-TD is a low delay method of temporal decomposition for line spectral frequency parameters. Meanwhile, F0 and noise ratio parameters are firstly described using the LEBEL-TD technique and then scalar quantized. Also, gain parameters are coded using spline interpolation. Subjective test results indicate that the performance of the proposed speech coding method is comparable to that of the 4.8 kbps US Federal Standard (FS-1016) CELP coder.