An Adaptive Variable Low Bit Rate Multi-Band Excitation Speech Coder

An adaptive variable rate speech coder based on the multi-band excitation (MBE) speech model is presented. The traditional MBE analysis and synthesis methods are employed and the two stage discrete cosine transformation schemes have been designed to encode the spectral envelope parameters in the speech coder. The scheme can adaptively and dynamically quantize the spectral envelope parameters which changed from frame to frame according to requested coding rate. This paper focuses on the design and implementation of two stage discrete cosine transformation coding scheme for 80071200/2400bps coding rates.