On the reduction of concatenation artefacts in diphone synthesis

One well-known problem with diphone concatenation is the occurrence of audible discontinuities at diphone boundaries, which are most prominent in vowels and semi-vowels. Significant formant jumps at certain boundaries suggest that the problem is of a spectral nature. We have examined this hypothesis by correlating the results of a listening experiment with spectral distances measured across diphone boundaries. The aim is to find a spectral distance measure that best predicts when discontinuities are audible in order to find out how the diphone database can best be extended with context-sensitive diphones. The results show that the KullbackLeibler measure is the best predictor.