Electronic musical instrument

An electronic instrument might include a user interface for controlling its sound, often by adjusting the pitch, frequency, or duration of each note. A common user interface is the musical keyboard, which functions similarly to the keyboard on an acoustic piano where the keys are each linked mechanically to swinging string hammers - whereas with an electronic keyboard, the keyboard interface is linked to a synth module, computer or other electronic or digital sound generator, which then creates a sound. However, it is increasingly common to separate user interface and sound-generating functions 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 Open Sound Control. The solid state nature of electronic keyboards also offers differing "feel" and "response", offering a novel experience in playing relative to operating a mechanically linked piano keyboard.


All 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 unclear.


In the 21st century, electronic musical instruments are now widely used in most styles of music. In popular music styles such as electronic dance music, almost all of the instrument sounds used in recordings are electronic instruments (e.g., bass synth, synthesizer, drum machine). Development of new electronic musical instruments, controllers, and synthesizers continues to be a highly active and interdisciplinary field of research. Specialized conferences, such as 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 musicology, electronic musical instruments are known as electrophones. Electrophones are the fifth category of musical instrument under the Hornbostel-Sachs system. Musicologists typically only classify music as electrophones if the sound is initially produced by electricity, excluding electronically controlled acoustic instruments such as pipe organs and amplified instruments such as electric guitars.


The category was added to the Hornbostel-Sachs musical instrument classification system by Sachs in 1940, in his 1940 book The History of Musical Instruments;^[1] the original 1914 version of the system did not include it. Sachs divided electrophones into three subcategories:


The last category included instruments such as theremins or synthesizers, which he called radioelectric instruments.


Francis William Galpin provided such a group in his own classification system, which is closer to Mahillon than Sachs-Hornbostel. For example, in Galpin's 1937 book A Textbook of European Musical Instruments, he lists electrophones with three second-level divisions for sound generation ("by oscillation", "electro-magnetic", and "electro-static"), as well as third-level and fourth-level categories based on the control method.^[2]


Present-day ethnomusicologists, such as Margaret Kartomi^[3] and Terry Ellingson,^[4] suggest that, in keeping with the spirit of the original Hornbostel Sachs classification scheme, if one categorizes instruments by what first produces the initial sound in the instrument, that only subcategory 53 should remain in the electrophones category. Thus, it has been more recently proposed, for example, that the pipe organ (even if it uses electric key action to control solenoid valves) remain in the aerophones category, and that the electric guitar remain in the chordophones category, and so on.