Voice conversion between synthesized bilingual voices using line spectral frequencies

Abstract

Voice conversion is a technique that transforms the source speaker individuality to that of the target speaker. We propose the simple and intuitive voice conversion algorithm not using training data between different languages and it uses text-to-speech generated speech rather than recorded real voices. The suggested method reconstructed the voice after transforming line spectral frequencies (LSF) by formant space warping functions. The formant space is the space consisted of representative four monophthongs for each language. The warping functions are represented by piecewise linear equations using pairs of four formants at matched monophthongs. In this paper, we applied LSF to voice conversion because LSF are not overly sensitive to quantization noise and can be interpolated. From experimental results, LSF based voice conversion shows good results for ABX and MOS tests than the direct frequency warping approaches.