Singing voice synthesizer with non-filter waveform generation using spectral phase reconstruction
Yasuhiro Hamada, Nobutaka Ono, Shigeki Sagayama · The Journal of the Acoustical Society of America · 2016
This paper discusses a singing voice synthesis system based on non-filter waveform generation using spectral phase reconstruction as an alternative method to replace the conventional source-filter model. Source-filter model has been considered as an essential technique in the long history of speech synthesis as it simulates the human process of speech production consisting of excitation and resonances, even after hidden Markov model was introduced in the 90s toward statistically trainable speech synthesis. Filter (particularly, recursive filter), however, may cause serious problems in undesired amplitude and long time decay when sharp resonances in recursive filter match harmonics of F0 of the excitation. As the ultimate purpose of usage of filter is to transfer the spectrogram designed in the TTS system to the listener’s hearing organs, an alternative solution can be brought from “phase reconstruction” without using filters. We propose a spectral phase reconstruction, instead of using filter, to generate waveform from the desired power spectrogram. We applied this framework to singing voice synthesis where fundamental frequency (F0) was modified according to the target melody. The result of the listening tests showed that the proposed method gives higher quality of naturalness than previous methods with recursive filter.