Thereminist's vocal ability while playing.

It is possible, but very challenging, it feels a bit like siging with two voices at once. Something to begin with would be things like singing a (semi) random note and then matching the pitch on the theremi and vice versa. Next suggested excercises would be humming or singing while playing the same melody line on the theremin; holding a steady pitch with the voice, maybe varying the voice timbre ad/or siging overtones, playing melody / melodic improv on the theremin, ad holding a steady pitch, perhaps just varying the volume and singing improvisation over that. 

Singing a melody and playing a second voice on the theremin simultaneously would be the advanced thing to practice toward, and I don't know if anyone has yet been able to demonstrate that, but it feels like possible when one keeps on trying and practicing enough.

Somewhat related, mainly in the beginning phases of learning to play the theremin I found myself involuntarily moving my mouth (subvocalising) and tensing my throat (trying to correct off-pitch notes), often mimicking singing without actually engaging the vocal chords. It felt like the brain/nerve area/connections/circuitry that control the vocal cords/tract and those of my arm/hand and to an extent to the whole body posture where getting rewired / connected.

I think I've heard/seen both Dorit Chysler and Clara Venice sing and play theremin simultaneously, but it might have been more 'swoops' / atmospheric effects and not so much precision playing of melody lines.

Maybe not quite what you had in mind, but you might like this:

The performer is a professional musician, YMMV trying this at home

[justify]

https://ru.wikipedia.org/wiki/Peter_Pringle

"It is possible, but very challenging, it feels a bit like singing with two voices at once."

"Singing a melody and playing a second voice on the theremin simultaneously would be the advanced thing to practice toward, and I don't know if anyone has yet been able to demonstrate that, but it feels like possible when one keeps on trying and practicing enough. Somewhat related, mainly in the beginning phases of learning to play the theremin I found myself involuntarily moving my mouth (subvocalising) and tensing my throat (trying to correct off-pitch notes), often mimicking singing without actually engaging the vocal chords. It felt like the brain/nerve area/connections/circuitry that control the vocal cords/tract and those of my arm/hand and to an extent to the whole body posture where getting rewired / connected.I think I've heard/seen both Dorit Chysler and Clara Venice sing and play theremin simultaneously, but it might have been more 'swoops' / atmospheric effects and not so much precision playing of melody lines."

Yes, when I first attempted, it was "Great Gig in the Sky." I felt a compulsion to since throat wanted to! ☺ So I absolutely get that and the v-chords, too!

Wanted to thank you, DreadVox, for your useful information! It was also cool to hear of similar experiences!

The style I noticed Peter using in "D L t S G D o M" was during vibratos. [B.B. King comes to mind, because his guitar w/ vocals style was very similar.] Does momentarily fool the listener, but if you only watch pitch hand ...

Still appreciate your participation(s)! Bendra first and all others! 😊 Martel.