A study of F0 modelling and generation with lyrics and shape characterization for singing voice synthesis

Natural pitch fluctuation is essential to singing voice. Recently, we have proposed a generalized F0 modelling method which models the expected F0 fluctuation under various contexts with note HMMs. Knowing that having F0 contours close to human professional singing promotes perceived quality, we are confronted with two requirements: (1) accurate estimation on F0 and (2) precise voiced/unvoiced decisions. In this paper, we introduce two techniques in the above directions. Influence of lyrics phonetics on singing F0 is considered to capture the F0 and voicing behaviour brought from different note-lyrics combinations. The generalized F0 modelling method is further extended to frequency-domain to study if shape characterization in terms of sinusoids helps F0 estimation or not. Our experiments showed that the use of lyrics information leads to better F0 generation and improves naturalness of synthesized singing. While the frequency-domain representation is viable, its performance is less competitive than time-domain representation, which requires further study.