In the domain of audio, a generic name for any one of a number of forms (electromagnetic wave, voltage) sound may take in the audio chain. As applied to electronics, a signal is any transmitted electrical impulse or a fluctuating electric quantity, such as voltage, current, or electric field strength, whose variations represent coded information. Operationally, a signal is the sound, image, or message transmitted or received in telegraphy, telephony, radio, television, or radar.

