VOICE CODING AND TREE ENCODING SPEECH COMPRESSION SYSTEMS BASED UPON INVERSE FILTER MATCHING.

Two speech compression systems based on codebooks of inverse filters produced by off-line linear predictive coding (LPC) and vector quantization techniques are considered. The first system is a pitch excited vocoder that is a variation on a speech coding system based upon vector quantization. The encoder selects an LPC inverse filter from a finite codebook that best ″matches″ an observed frame of sampled speech. This filter is in turn used to determine the voicing and digitized pitch information. Unlike LPC systems, the digitization is performed in a single step on the data rather than separate modeling and digitization steps. The second system is a tree encoding system that uses the filter selected by an inverse filter matching vocoder to ″color″ a tree that is then searched for a minimum distortion path for the original sampled speech waveform. The two systems are described, simulated, and compared with other similar systems.