I come from Vocaloid and I’m happy of Synth V! I really needed a true-to-life voice and there’s no match, Synth V wins by far. Yet, I had a parameter in Vocaloid which could control mouth openness continuously: it’s not in Synth V yet (1.8.1) and I really miss it for two main reasons:
continuous variation of this parameter enchances realism. Synthesized vocals tend to be very clear in pronunciation, while real singers sometimes put some mud into it, reason is that mouth is sometimes more closed.
some English phonemes “eh” and “aa” need to be corrected sometimes, more open or more closed than the Database.
I ask a continuous control in the parameter area for mouth openness, but also a slider in the note panel would do
Currently some voice database have vocal modes for mouth open/closed (or both), however this is far from ideal since it’s not a universal feature.
Hopefully Dreamtonics can work to expand the existing parameter options, but considering even Vocaloid got rid of most of their parameters for their AI voices, I have to wonder if there’s some major technical obstacle… only time will tell I suppose.
Anyway, here’s a list of current voice databases with open/closed vocal modes:
From your answer I guess that Yamaha understood that there was a better way of doing the open/closed mouth than a continuous parameter, that is recording a new voice database: a different approach. We might discuss what synthesizing a voice is, and how much sampling is involved (related on how we use it, to fake real vocals or to make music with intended synthesized voice: also synths in the 70s did the sine wave oscillator to reproduce a flute, in the 80s they sampled the flute and it was way more realistic, now we go back to analog synths for their imperfect sound but peculiar). History of voice synths is going now to realism and sampling, also in the compatible voices for Synth V, your list shows that the most recent voice databases have that option, but the solution is recorded from the start, not a synth parameter.