The physical modeling synth Notes is using is based on something called waveguide synthesis, which turns out to be pretty easy to implement. The main difficulty lies in changing the length of the waveguide without getting glitches, which can be done by crossfading to a second waveguide.

In comparison to sample-based technology, the sound isn't as accurate, but in terms of performance, just about nothing comes close.

Did I mention it's also computationally inexpensive?

There have been two issues with it catching on. The first is the patents, which I believe are due to expire this year. So there's hope that some VSTis may be developed.

The second issue is a lack of inexpensive breath controllers. Wind controllers aren't cheap, and at this point, I don't think anyone is still manufacturing breath controllers (although someone has been promising come out with one for the last couple of years).

And it's the performance that sells physical modeling. Without that, it sounds like cheap synthesis.

-- David Cuny
My virtual singer development blog

Vocal control, you say. Never heard of it. Is that some kind of ProTools thing?