Improving Formant and Concatenative Speech Synthesis Techniques through Using Vocoders

In this paper an approach to improve the quality of synthetic speech in formant and concatenative synthesis techniques is described. To deal with this problem we focused on using vocoders. In concatenative speech synthesis the idea is based on post processing the generated speech to reduce discontinuities. The post processing is consists of integrating Straight method to synthesis system in order to smooth the boundary between units. On the other hand, in formant synthesis we used multi excitation linear predictive method to replace simple excitation signal in Klatt method with multiband excitation. Our synthesis techniques were evaluated with respect to naturalness, fluidity and intelligibility based on subjective methods. These experiments clarified that the naturalness of synthetic speech can be improved by using our smoothing methods and multiband excitation signal.