An electronic musical instrument or electrophone is a musical instrument that produces sound using electronic circuitry. Such an instrument sounds by outputting an electrical, electronic or digital audio signal that ultimately is plugged into a power amplifier which drives a loudspeaker, creating the sound heard by the performer and listener.
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.
