How a synthesiser makes electronic music
When you listen to music, what you hear is a blend of regular vibrations - of a violin string, the reeds in an oboe, or the column of air in a trumpet, for example. The greater the rate of vibration (the frequency), the higher the sound, or pitch.
When a violin, an oboe, and a trumpet play the same note, they all produce a pure (fundamental) vibration of the same frequency. What makes instruments sound different are the overtones (harmonics) that result from fractional vibrations on top of the fundamental vibration.
A violin string, for instance, vibrates along the whole of its length to produce the fundamental pitch, but each half and quarter of the string vibrates as well to give overtones. Instruments bring out different mixtures of overtones according to their shape and materials, and the vibrations resound in the body of the instrument to create its distinctive quality.
An electronic synthesiser makes music by generating electric current in a wide range of frequencies. When the current is fed to a loudspeaker, the fundamental sounds and overtones of all sorts of instruments are simulated, as well as many sound effects. As a synthesiser can rarely simulate all the continually changing overtones of a conventionally played instrument, it generally lacks the same richness, but modern types get very close.
Synthesisers are used by pop musicians in company with conventional instruments to make 'live' electronic music. They can be linked with microphones and other synthesisers, or they can be played by a tape recorder or computer. Some can be fed with patches (push-in computer program discs or boards) that create different sounds. Some modern digital synthesisers have built-in computers and can produce complex overtones. Some use FM (frequency modulation) synthesis, a process similar to modulating radio waves.
With modern synthesisers that use a computer-connection system called MIDI (Musical Instrument Digital Interface), the player can feed in sounds from various instruments or another computer or synthesiser to obtain a wide variety of effects. With a digital electronic instrument known as a sampler, sounds can be fed in and replayed at all pitches across a keyboard.
Synthesisers are also used for composing music. Herbert Eimert and Karlheinz Stockhausen set up the first electronic music studio in Cologne, Germany, in 1953, and Stockhausen is one of the foremost composers of electronic music. Others include the Americans Milton Babbitt and Morton Subotnik. Subotnik's Silver Apples of the Moon (1967) was the first electronic work to be composed for recording. The score for Koyaanisqatsi, a 1982 film based on North American Indians, included electronic music by the American composer Philip Glass.