Audiovisual tools and instruments
- 1920, Lev Termen, Russia, invented the Aetherophone (later called the Theremin or Thereminovox). The instrument used 2 vacuum tube oscillators to produce beat notes. Musical sounds were created by "heterodyning" from oscillators which varied pitch. A circuit was altered by changing the distance between 2 elements. The instrument had a radio antenna to control dynamics and a rod sticking out the side that controlled pitch. The performer would move his/her hand along the rod to change pitch, while simultaneously moving his/her other hand in proximity to the antenna. Many composers used this instrument including Varese. // He was a Russian physicist who invented the instrument made of vacuum tubes and oscillators. In 1927 he was allowed to go to the US to promote his instrument and to spy for the Soviets. He returned to Russia in late 1938. [He was later abducted by operators of Stalin and taken back to Moscow where he is forced to work on devices for the Soviet Ministry of Internal Affairs.] He was sent to Siberia for a year and then back to Moscow to work on aircraft design. He later designed some listening devices. [see 1945]. The 1994 film "Theremin: An Electronic Odyssey," featured the instrument. 
- Hungarian Sándor László (Sonchromatoskop, 1920)
- colour piano, Zdenek Pesanek, CS, which was able to produce a light-kinetic sculptural painting, where the keys could also trigger the scenic means of the painting and the colour changes within the illuminated embossment work, in dynamic interplay with a mechanical spectrophone (reflector play).
- The composer Miroslav Ponc after his activity in Berlin (1922-23) independently contributed to the contemporary theme of the colour piano - for instance in his work Big Canonical Preludium.
- The Rhythmicon, Henry Cowell & Leon Termen, USA 1930 
- The Terpsitone, Leon Termen, USA/USSR 1930 
- The Theremin Cello, Leon Termen, USA 1930 
- The Sonar, N.Anan'yev, Soviet Union, c1930 
- The "Ekvodin", V.A.Gurov, Soviet Union, 1931 
- The Variophone, Yevgeny Sholpo, Soviet Union, 1932 
- The Emiriton, A.Ivanov & A.Rimsky-Korsakov, Soviet Union, 1932 
- The ANS synthesizer, Eugene Murzin, Soviet Union 1958  
- Zauberhafte Klangmaschinen, exhibition, Sep 2008 - Apr 2009, Hainburg. The exhibition MAGICAL SOUND MACHINES relates the (hi)stories of sound generators, sound recorders and sound transmitters. The extensive presentation will kiss awake ariston, mellotron, rhythmicon and many other, partly forgotten sound machines from their hundred-year sleep so that young and old, the general public and experts alike can experience and enjoy them on an interactive discovery tour. http://www.ima.or.at/klangmaschinen/?cat=8&language=en