An electronic musical instrument is a musical instrument that produces its sounds using electronics. In contrast, the term electric instrument is used to mean instruments whose sound is produced mechanically, and only amplified or altered electronically - for example an electric guitar.
The instrument may include a user interface for controlling its sound, often by adjusting the pitch, frequency, or duration of each note. However, it is increasingly common for the user interface and sound-generating functions to be separated into a music controller (input device) and a music synthesizer, respectively, with the two devices communicating through a musical performance description language such as MIDI or OSC.
All electric and electronic musical instruments can be viewed as a subset of audio signal processing applications. Simple electronic musical instruments are sometimes called sound effects; the border between sound effects and actual musical instruments is often hazy.
French composer and engineer Edgard Varèse created a variety of compositions using electronic horns, whistles, and tape. Most notably, he wrote Poème Électronique for the Phillips pavilion at the Brussels World Fair in 1958.
Electronic musical instruments are now widely used in most styles of music. The development of new electronic musical instruments, controllers, and synthesizers continues to be a highly active and interdisciplinary field of research. Specialized conferences, notably the International Conference on New interfaces for musical expression, have organized to report cutting edge work, as well as to provide a showcase for artists who perform or create music with new electronic music instruments, controllers, and synthesizers.
In 1878, Thomas A. Edison patented the phonograph, which used cylinders similar to Scott's device. Although cylinders continued in use for some time, Emile Berliner developed the disc phonograph in 1887.
A significant invention, which was later to have a profound effect on electronic music, was Lee DeForest's triode audion. This was the first thermionic valve, or vacuum tube, invented in 1906, which led to the generation and amplification of electrical signals, radio broadcastng, and electronic computation, amongst other things.
The Telharmonium is the first music synthesizer. In 1898 Thaddeus Cahill patented an instrument called the Telharmonium (or Teleharmonium, also known as the Dynamaphone). Using tonewheels to generate musical sounds as electrical signals by additive synthesis, it was capable of producing any combination of notes and overtones, at any dynamic level. This technology was later used to design the Hammond organ. Between 1901 and 1910 Cahill had three progressively larger and more complex versions made, the first weighing seven tons, the last in excess of 200 tons. Portability was managed only by rail and with the use of thirty boxcars. By 1912, public interest had waned, and Cahill's enterprise was bankrupt.
Another development, which aroused the interest of many composers, occurred in 1919-1920. In Leningrad, Leon Theremin (actually Lev Termen) built and demonstrated his Etherophone, which was later renamed the Theremin. This led to the first compositions for electronic instruments, as opposed to noisemakers and re-purposed machines.
Composers who ultimately utilized the Theremin included Varèse—in his piece Ecuatorial (1934)—while conductor Leopold Stokowski experimented with its use in arrangements from the classical repertory. In 1929, Joseph Schillinger composed First Airphonic Suite for Theremin and Orchestra, premièred with the Cleveland Orchestra with Leon Theremin as soloist.
This decade brought a wealth of early electronic instruments—along with the Theremin—, there is the presentation of the Ondes Martenot, which was designed to reproduce the microtonal sounds found in Hindu music, and the Trautonium. Maurice Martenot invented the Ondes Martenot in 1928, and soon demonstrated it in Paris. Composers using the instrument ultimately include Boulez, Honneger, Jolivet, Koechlin, Messiaen, Milhaud, Tremblay, and Varèse. In 1937, Messiaen wrote Fête des belles eaux for 6 ondes Martenot, and wrote solo parts for it in Trois petites liturgies de la Présence Divine (1943–44) and the Turangalîla Symphonie (1946–48/90).
The Trautonium was invented in 1928, and in 1940, Richard Strauss used Trautonium in his Japanese Festival Music. This new class of instruments, microtonal by nature, was only adopted slowly by composers at first, but by the early 1930s there was a burst of new works incorporating these and other electronic instruments.
Dr. Robert Moog introduced the first practical commercial modern music synthesizer with his Moog synthesizer. This instrument used a series of tone generators with keys that would adjust the tone generators' pitch. Moog resolved to design and sell Theremins to gain enough money to engineer this synthesizer.
The first digital synthesizers were academic experiments in sound synthesis using digital computers. FM synthesis was developed for this purpose, as a way of generating complex sounds digitally with the smallest number of computational operations per sound sample.
According to Dictionary.com Unabridged, the term "electronic music" (which, as defined in 2006 includes the tape recorder as an essential element: "electronically produced sounds recorded on tape and arranged by the composer to form a musical composition") first came into use during the 1930s
This was a small, integrated synthesizer that made analog synthesis easily available and affordable and became the most widely used synthesizer in both popular and electronic art music.
In 1983, Yamaha introduced the first stand-alone digital synthesizer, the DX-7. It used frequency modulation synthesis (FM synthesis), first experimented with by John Chowning at Stanford during the late sixties.
The impact of computers continued in 1956. Lejaren Hiller and Leonard Isaacson composed Iliac Suite for string quartet, the first complete work of computer-assisted composition using algorithmic composition.
The advent of MIDI technology allows a single keystroke, control wheel motion, pedal movement, or command from a microcomputer to activate every device in the studio remotely and in synchrony, with each device responding according to conditions predetermined by the composer.
MIDI instruments and software made powerful control of sophisticated instruments easily affordable by many studios and individuals. Acoustic sounds became reintegrated into studios via sampling and sampled-ROM-based instruments.
Miller Puckette developed graphic signal-processing software for 4X called Max (after Max Mathews) and later ported it to Macintosh (with Dave Zicarelli extending it for Opcode ) for real-time MIDI control, bringing algorithmic composition availability to most composers with modest computer programming background.
By far the most common musical controller is the musical keyboard. Other controllers include the radiodrum, Akai's EWI, the guitar-like SynthAxe, the BodySynth, the Buchla Thunder, the Continuum Fingerboard, the Roland Octapad, and various isomorphic keyboards including the Thummer.