Clara Rockmore had to play the rests, too

In her 1979 conversation with Charles Amirkhanian and Laurie Spiegel (known today only through a back-translation from German), Clara Rockmore described inventing interval exercises for herself. She practised from one C to the next and through all the intervals in between. A hand moving freely in the air still needed a trained sense of distance; even small bodily movements could disturb a pitch.

“I have to play the rests as well as the notes,” Rockmore told Robert Moog in 1977. When she did not want to connect two notes, she lowered the volume with her left hand, moved her right to the next pitch, then restored the volume.

A theremin she never touched kept sounding until she stopped it; the unbroken tone did not force her to join every note. She could choose where to make a musical breath.

Rockmore recorded Rachmaninoff's Vocalise with her sister, the pianist Nadia Reisenberg.