An HNM-Based Speaker-Nonspecific Timbre Transformation Scheme for Speech Synthesis

In this paper, the harmonic-plus-noise model (HNM) based speech signal synthesis scheme studied previously is further extended to provide the function of speaker nonspecific timbre transformation. To transform synthetic speech´s timbre, we have developed a formant based frequency mapping method called piece-wise linear frequency mapping (PLFM). In addition, a commonly adopted method is frequency axis scaling (FAS). Both methods have been integrated into our HNM speech synthesis scheme, and a realtime synthesis system is implemented according to this scheme. The perception test results show that the proposed scheme can indeed transform the source timbre of a female adult into the timbre of a male adult, boy, or girl. In addition, the method PLFM is shown to be better than FAS for obtaining more manful timbre.