Quality enhancement of sinusoidal transform vocoders

The authors present quality enhancement of sinusoidal transform coders (STCs) via the development of parametric models. The benefits of the Bark spectrum are explored for use in the design of perceptual coding of the sine-wave amplitudes. According to the results, the proposed approach provides a uniform perceptual fit across the spectrum. To enhance the accuracy of phase representation, noncausal all-pole modelling of the vocal system is also discussed. Experimental results indicate that the use of the developed new parametric models allows the STC to improve the phase accuracy as well as the synthetic speech quality