She was the best in the world on an instrument you do not touch

Clara Reisenberg was four years old when she was admitted to the Imperial Conservatory of Saint Petersburg, and to this day nobody has got in younger. It was 1915, she had been born in Vilna on 9 March 1911, and she was so small that she played her audition standing on a table. They took her for violin and put her with Leopold Auer, the teacher who had trained Jascha Heifetz and Mischa Elman — that is, the man to whom they sent the children everything was expected of.

Because what came next was not a career. It was the revolution, the civil war and five years of not eating enough. The family made its way south and west with the instrument and little else, and reached the United States in 1921. Clara was ten years old and had spent half her life poorly nourished, through the years in which joint cartilage is laid down.

Her bow arm was the first to give warning: pain, and then a right hand that would not hold the pressure a string demands four hours a day. In New York she had gone on studying violin with Auer, who had emigrated too, and in 1928 the Curtis Institute in Philadelphia admitted her to carry on with him. It lasted less than two months: the pain came back within weeks and in November she left the school. Doctors put a name to what malnutrition had done to her joints and tendons: arthritis. She was seventeen. The youngest student in the history of the Imperial Conservatory of Saint Petersburg gave up the violin. The arm did not make it to the end of the concert.

What she did then has no precedent in music.

Lev Sergeyevich Termen, a Soviet engineer and physicist, who signed himself Leon Theremin in the West, had invented in the 1920s a device that sounded when you brought your hands near it. It works by electrical capacitance: two antennas generate fields, and your own body, entering them, alters them. A vertical antenna controls the note; a horizontal loop, the volume. No keys, no strings, no mouthpiece: nothing to press. You do not touch it. You put your body in front of it.

Termen demonstrated it in Europe and reached New York at the end of the twenties. RCA bought the licence and in 1929 put it on sale as a parlour cabinet; about five hundred were sold and it failed almost at once. The underlying reason was not the year: without keys there is nowhere to put your finger. The note is a point in the air, and the point moves if you move.

Clara Reisenberg met Termen in New York. She arrived with the ear of a violinist trained by Auer and with broken hands, and found herself in front of an instrument that demanded exactly what she had left — absolute pitch, memory of positions, control to the millimetre — and none of what she had lost, because there was nothing to press.

What happened from there is a technical collaboration, not a romance, although Termen tried to make it both: he proposed marriage and she said no. She married a lawyer, Robert Rockmore, and signed the rest of her life with his surname.

She asked him for changes and he made them. The main one: the volume loop responded too slowly. On a parlour theremin, the sound rises and falls like a siren, which is why the instrument became famous for playing ghosts; what you could not do was cut one note clean and start the next. Termen built her custom instruments with a much faster volume response and with the pitch field adjusted to her way of measuring space.

With that, she invented the technique. And here is what separates her from everyone else: amateurs played the theremin by sliding a hand, hunting for the note the way you hunt for a light switch in the dark. Clara Rockmore stopped sliding. She fixed finger positions — one configuration of the hand for each interval — and learned to jump from one note to another by opening and closing her hand in the air, without travelling the distance in between. At the same time, with her left hand, she moved in and out of the loop to articulate: every note began and ended when she decided. She gave the instrument the one thing it lacked, which was the full stop and the comma.

It is called aerial fingering, and she invented it.

There is a detail that explains why nobody else managed it. On a theremin the player is part of the circuit: the note depends on the electrical capacitance of the whole body, not just the hand. Turn your head and the note moves. Breathe deeply and it moves. Playing it in tune means staying absolutely still from the shoulders down for the whole piece and moving only two hands, and it also means knowing what an F sharp sounds like before you produce it, because there is nothing to look at. Clara Rockmore had absolute pitch and all those years with Auer behind her, first in Russia and then in New York. With a theremin in front of her, that was the entire equipment needed.

She made her solo debut on 30 October 1934, at Town Hall in New York. Then came the orchestras: Bloch's Schelomo with the Philadelphia Orchestra, and the premiere of a concerto Anis Fuleihan wrote for her, conducted by Leopold Stokowski. Between 1940 and 1943 she crossed the country coast to coast three times on tour with the bass-baritone Paul Robeson. Her sister Nadia, the concert pianist, accompanied her, in a repertoire that did not exist: there are no classical works written for theremin, so she played Rachmaninov, Ravel and Saint-Saëns in transcription, plus the occasional new commission. Her signature piece was Rachmaninov's Vocalise, written for a voice that sings without words, which in her hands did not need them either. The critics of the day wrote about her vibrato and her intonation, not about the trick.

In 1945, the score of Hitchcock's Spellbound used a theremin for the hero's vertigo. Miklós Rózsa's score for that film won the 1946 Oscar, and the sound went into the prize with it. In 1951, The Day the Earth Stood Still used it for flying saucers. Within twenty years, the sound Clara Rockmore had turned into a concert instrument was fixed in the public's head as the effect of the supernatural and of Martians. They asked her for the noise. She refused to make the noise.

The halls closed to her one by one and she spent three decades barely recording.

A manufacturer rescued her. Robert Moog had built theremins as a boy, before the synthesizers that carry his surname, and knew perfectly well who she was. In the 1970s he and his wife, Shirleigh, talked her into a studio. Clara was in her late sixties and had spent half a lifetime without an audience. Nadia sat at the piano, as in 1934. The record came out in 1977 and was called The Art of the Theremin.

That is what put her back on the map, and this time for good: the recordings anyone can listen to today come from that record, and so does the technique taught today: Lydia Kavina, Termen's great-niece and his pupil from the age of nine, began teaching with those recordings in front of her. In 1993 she appeared in the documentary Theremin: An Electronic Odyssey, aged eighty-two, explaining with her hands what it had taken her half a life to be allowed to explain. She died in New York on 10 May 1998, at eighty-seven.

On the 1977 takes, at the end of each musical phrase, she did what she had begun doing forty-seven years earlier so that the thing would stop being a siren: she moved her left hand slowly towards the volume loop, until it was almost against it, and closed the note dead.