two pairs of heterodyne oscillators, for both pitch and volume. Performance technique Important in theremin articulation is the use of the volume control antenna. Unlike touched instruments, where simply halting play or damping a resonator in the traditional sense silences the instrument, the thereminist must "play the rests, as well as the notes", as Clara Rockmore observed. If the pitch hand is moved between notes, without first lowering the volume hand, the result is a "swooping" sound akin to a swanee whistle or a glissando played on the violin. Small flutters of the pitch hand can be used to produce a vibrato effect. To produce distinct notes requires a pecking action with the volume hand to mute the volume while the pitch hand moves between positions. Thereminists such as Carolina Eyck use a fixed arm position per octave, and use fixed positions of the fingers to create the notes within the octave, allowing very fast transitions between adjacent notes. Although volume technique is less developed than pitch technique, some thereminists have worked to extend it, especially Pamelia Kurstin with her "walking bass" technique and Rupert Chappelle. Recent versions of the theremin have been functionally updated: the Moog Ethervox, while functionally still a theremin, can also be used as a MIDI controller, and as such allows the artist to control any MIDI-compatible synthesizer with it, using the theremin's continuous pitch to drive modern synths. The Harrison Instruments Model 302 Theremin uses symmetrical horizontal plates instead of a vertical rod and horizontal loop to control pitch and volume, with the volume increasing as the hand approaches the plate. Music From The Ether manufactures a modernized vacuum tube replica of the RCA AR-1264 and a transistorized theremin which the customer may customize with a desired wood species, as well as many available tolex colors with matching knobs. The critic Harold C. Schonberg described the sound of the theremin as "(a) cello lost in a dense fog, crying because it does not know how to get home." Uses Concert music The first orchestral composition written for theremin was Andrei Pashchenko's Symphonic Mystery, which premiered in 1924. However, most of the sheet music was lost after its second performance. Other concert composers who have written for theremin include Bohuslav Martinů, Percy Grainger, Christian Wolff, Joseph Schillinger, Moritz Eggert, Iraida Yusupova, Jorge Antunes, Vladimir Komarov, Anis Fuleihan, and Fazıl Say. Another large-scale theremin concerto is Kalevi