Very Low Bit Speech Coding Using Fractal Systems.

点击翻译按钮获取中文摘要

A very low bit rate speechcoder at 1.2kbpsis newly proposedln this coder which is similar to the LPC vocoder, speechsignal is synthesizedusing sinusoids whose frequenciesare multiple of the fundamental frequency, and whose amplitudes are adaptively modulated based on auditory perceptualcharacteristics, in order to improve the quality.In this study, the basics of the new sinusoids synthesizerare introduced, thenhow to modulate the sinusoids based on perceptual characteristics is explained. The auditory perceptual characteristics are simulated by Gammatonefilters. And a new segment coder of spectral information (LSP coefficients) using DP matchingis also proposedtoreduce the total bit rate to 1.2kbps. According to MOS test (5 grades), the subjectivequality of the synthesized speech is improved by 1.0 compared with that of the simple LPC vocoder.