Theremin

Widely regarded as one of today's most important composers of orchestral music, Kalevi Aho has written fifteen symphonies as well as over twenty concertos. The horn concerto is a one-movement work with a 'ritualistic' element: the horn’s first entries are heard from backstage, after which the soloist enters the stage, moving gradually from left to right before leaving the stage again towards the end.

The theremin was invented in 1919 and became the first electronic musical instrument that had a career in the XX-century and it is still the only instrument which can be played without any mechanical touching. The theremin-player moves his hands near two antennas. The proximity of the right hand to the vertical antenna changes the electromagnetic field thus changing the pitch of the sound over a six-octave range. Left hand controls the volume. Theremin's sound remembers sometimes the cello or violin, sometime the flute and often the human voice. The instruments circuit uses a beat frequency oscillator, in which an audible musical tone is derived from the beating between two high-frequency oscillators. The frequency of one of the oscillators is fixed. The frequency of the other is altered by the performer's proximity to the pitch antenna.