Geometrically and acoustically optimized codebook for unique mapping from formants to vocal-tract shape

A method to generate a codebook with distributed formant targets and unique geometric-acoustic mapping from formants to vocal-tract shape by direct acoustic calculation is proposed. Geometric and acoustic constraints are applied to both vocal-tract model parameters and calculated acoustic features to eliminate unacceptable values from the initial codebook which usually has an extremely large codebook size. The vocaltract length is used as an additional parameter to model the vocal-tract. Restriction on the vocal-tract length based on some measured data is employed. A geometric and acoustic optimization scheme is devised to cluster the constrained codebook into an uniquely mapped codebook with reduced size. The codebook generated by this method is precise and robust and provides a satisfactory solution to the inverse speech production problem.