Efficient Technique for Quantization of Pitch Contours

This paper introduces an efficient technique for pitch contour quantization designed mainly for applications that require storage of speech or prosodic information at a high compression ratio. Instead of quantizing the estimated pitch values directly, the proposed technique forms and quantizes a simplified model of the pitch contour. The simplified contour is constructed in such a manner that the amount of information needed for describing it is minimized. At the same time, the deviation from the original contour is maintained below a predetermined limit. In addition to the high compression ratio, the contour representation offers benefits in pitch-synchronous decoding. The proposed technique is implemented and evaluated in a practical storage speech coder. According to the evaluation, the performance of the quantization technique is very promising as it achieves perceptually satisfactory quality at an average bit rate of about 100 bits per second.