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Theremin: The Instrument You Don’t Need To Touch When Playing


[Image source: ThereminWorld]

We all love music to its core, and no matter what our genre preferences are, all of us agree that music is food for the soul. Most of the people categorise musical instruments as either woodwind, strings, percussion or brass. But today we are going to cover an instrument that can be played without ever touching it!

This amazing instrument is called the Theremin, etherphone or thereminophone. It was invented a Russian, Leon Theremini in 1928 and is one of the oldest electric instruments in the world. To play it, the player doesn’t require any physical touch whatsoever, instead players’ hand position between two antennas is utilised to create amazing tunes.

[Image source: ThereminWorld]
The music works by controlling oscillation for the frequency with one hand, and amplitude of the volume with the other. The resulting electric signals are amplified and sent to a loudspeaker. The pitch of the sound changes when the player moves his hands closer to the antenna, and likewise the volume increase when the other hand is moved closer to the opposite antenna.

The device uses the same phenomenon involved in capacitors which stores electric charge made up of two plates conducting electricity via ‘dielectric’ like mica paper or air. So when an electric charge builds up, its flow is blocked between the plates by the dielectric. This helps in building up the charge on one side which eventually can be moved down a wire to the other side of the capacitor. This practice creates an alternating current that oscillates at a certain rate of frequency.

Theremins uses the phenomenon with a slight modification, as it holds one plate of the capacitor in its antenna while the other capacitor plate is the musician’s hands, which gives the musician full control of oscillating the current and hence, the tunes. When the musician moves the capacitor plate, i.e. his hand close to the antenna, the plates store more charge, and consequently the current oscillates at a lower frequency; vice versa when he moves the hand away. This change in the current is amplified to vibrate the speaker and create sound waves.

[Image source: ThereminWorld]
Originally, the current produced has a frequency of around 250 kHz, which is beyond human perception. So, to make it audible, the theremin uses heterodyning where it mixes the oscillating current with another pre-set current. These currents are mixed together and superimposed to produce a current with audible range frequency, which is typically within the range of a piano.

During this, the frequencies switch order meaning higher becomes lower, and the lower becomes higher. So that’s the reason why the speaker produces the higher notes when your hand is closer to the theremin, and lower notes if your hand is farther away.

What are your thoughts on this unusual blend of art and engineering? Comment below!

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