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.

"It is possible, but very challenging. It feels a bit like singing 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 theremin and vice versa. Next suggested excercises would be humming or singing while playing the same melody line 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."

Months ago, Deadvox was speaking to me (above) on the subject last Feb. Wanted to let him know I may be able to demonstrate a vocal sing-a-long on a [Steve Walsh (KANSAS) keyboardist] song "Every Step of the Way." Was trying to play the solos in the song on the etherwave plus today and got excited about how well it blended with the saxophone! 
After solos were done in the song, I attempted vocals while playing notes, just for fun, not taking myself too seriously, during my duet with SW and wished I'd known it was going to be worthy of recording!  

I've been incorporating it in my practicing and improvisations/jams, and getting better at combining singing voice and theremin playing simultaneously. Humming and playing the same melody and/or scales is working out well, as well as combining overtone singing and theremin, with the voice holding a steady ground tone and the overtones and the theremin, or folowing the same melody lines with the voice adding overtones and timbre variations. Simple songs like well known children's songs and mantras following the melody or choosing tones that are within the chord also is going quite well by now.
So I can also confirm that it's doable.

Perhaps we upload our vocal beginning(s) here, from a decent performance point (we feel good showing?) Not at all meaning these beginnings would be without error(s)! At least mine, guarantee errors while recording! I could post a less than 4 star performance and be ok with it. Feel that more people could witness the progress and get inspired to try.

While playing theremin in-the-zone, this vocal ability is easier. Yes?