Generally considered the greatest theremin player in history. Her first solo performance was on October 30, 1934. I have a CD of her playing; it's quite amazing. The theremin sounds more like a human voice than anything else, like a person with a huge vocal range who never needs to draw breath. Or else like a violin; it's hard to pin down the sound precisely.
They say she actually had aerial "fingering" techniques, using the shape of her hand and fingers to fine-tune the tone of the instrument. It's also been conjectured that she had a large speaker set up directly behind her so she could hear the nascent sounds she was playing before they were loud enough for the audience to hear and thus be able to make last-second adjustments to the sound. It also was apparently a fine visual effect, since she was a small woman, and the huge speaker towering behind her made for an interesting contrast.