Before revision:   However, we observe that  completely dispensing with any duration modelling introduces occasional instabilities in the generated spectrograms.
After revision:  Despite this, it shows a strong improvement in naturalness with respect to previous neural singing synthesis models. The model does not require any durations or pitch patterns as inputs, and learns to insert vibrato autonomously according to the musical context. However, we observe that completely dispensing with any duration modelling introduces occasional instabilities in the generated spectrograms.