A comparison of synthetic speech quality generated by the residual‐and multipulse‐excited analysis‐synthesis methods
Shoichi Takedas, Yoshiaki Asakawas, Akira Ichikawas · Electronics and Communications in Japan (Part III Fundamental Electronic Science) · 1991
Abstract A source coding technique using multiple excitation pulses is expected to improve the quality of rule‐based synthetic speech. In this paper, residual‐ and multipulse‐excited analysis‐synthesis methods are compared by evaluating the relationship between speech quality and bit rates. A method is proposed for reducing bit rates by thinning out prediction residual pulses (Thinned‐Out Residual method). At excitation pulse utilization rates greater than 50 percent, this residual‐excited analysis synthesis method produces higher‐quality (segmental SNR) speech than the multipulse‐excited analysis‐synthesis method. When high‐quality synthetic speech is required, the optimal residual utilization rate therefore is 100 percent. When a low bit rate is required, however, the pulse number should be reduced greatly. The multipulse‐excited analysis‐synthesis method then synthesizes speech with a higher segmental SNR.