Residual Conversion Versus Prediction on Voice Morphing Systems

Many of the research efforts in voice morphing, or also called voice conversion (VC), has been carried out in the field of vocal tract mapping. It has been studied that in the vocal tract parameters there is the most relevant part of the information about speaker identity. However, to achieve an effective personality change it is also needed to modify the glottal flow characteristics of the source speaker. In this paper two strategies of transformation of LPC residual signals for a voice morphing system based in LSF mapping are compared: conversion of the source residual by codebook mapping and prediction of the target residual from LSF vectors. Experimental results demonstrates that the relationship between LSF parameters and their residual signals is higher that the relationship between LPC residual signals of two different aligned speakers