Results of a Study of the Linear Prediction Vocoder

The Linear Prediction Vocoder (LIPREDER) System is an analysis-synthesis speech processing system which efficiently converts speech into digital form at voiceband data rates. The objective of our study was to optimize the LIPREDER system in terms of performance and complexity for a wide selection of talkers and sentences at data rates of 3600 and 7200 b/s. The optimized LIPREDER system produces synthetic speech quality which represents a substantial improvement over previous voice encoders operating at voiceband data rates. Evaluation results indicate that for most talkers and text there is little or no perceptible quality difference between the synthetic speech produced by LIPREDER systems at 3600 and 7200 b/s. Additionally, implementation of the LIPREDER system appears to be technically feasible.