Low frequency oscillation, often abbreviated to LFO, is a term that predominantly refers to an audio technique specifically used in the production of electronic music. In addition to the main oscillator(s) of a synthesizer, which is responsible for the creation of the audio signal itself, an LFO is an additional oscillator that operates at a comparatively lower frequency (hence its name), that modulates the audio signal, thus causing a difference to be heard in the signal without the actual introduction of another sound source. Low Frequency Oscillation as a concept was first introduced in the modular synths of the 1960s and 70s — often its effect was 'accidental'; such were the extensive capabilities of a modular synth operator to patch the instrument to create a vast array of different configurations. They have since appeared in some form on almost every synthesizer, and more recently other electronic instruments such as samplers have included them, to augment their capacity for sound alteration. Sound effects or audio effects are artificially created or enhanced sounds, or sound processes used to emphasize artistic or other content of movies, video games, music, or other media. ... Electronic music is a term for music created using electronic devices. ... An electronic oscillator is an electronic circuit that produces a repetitive electronic signal, often a sine wave or a square wave. ... A classic FM synthesizer, the Yamaha DX7. ... Audio can mean: Sound that can be heard. ... Sine waves of various frequencies; the lower waves have higher frequencies than those above. ... Modulation is the process of varying a carrier signal, typically a sinusoidal signal, in order to use that signal to convey information. ... The 1960s decade refers to the years from 1960 to 1969, inclusive. ... The 1970s decade refers to the years from 1970 to 1979, inclusive. ... Sine, square, triangle, and sawtooth waveforms The modular synthesizer is an early type of synthesizer consisting of separate modules which must be connected by wires to create a so called patch. ... An electronic musical instrument is a musical instrument that produces its sounds using electronics. ... An AKAI MPC2000 sampler A sampler is an electronic musical instrument that can record and store audio signal samples, generally recordings of existing sounds, and play them back at a range of pitches. ...

The principle behind low frequency oscillation as a means of modulating a signal, as opposed to adding to it, is that its frequency is lower than the audible frequency of the human ear (20Hz–20kHz) i.e., the frequency is low enough so that it isn't heard as a tone. The hertz (symbol: Hz) is the SI unit of frequency. ...

A low frequency oscillator can be routed to control a variety of different parameters, for example the frequency of the audio oscillator, the phase, panning, filter frequency, or the velocity of the syntheszier's output. For instance, when routed to pitch, an LFO serves to simulate vibrato, and when an LFO modulates amplitude (volume), it creates tremolo. On most synthesizers and sound modules, there are several different ways in which the user can alter the effect produced by the LFO. These may include a variety of different waveforms, a rate control, routing options (as described above), a tempo sync feature, and an option to control the amount by which the LFO will modulate the audio signal. Phase, from the Greek phasis, meaning appearance, has a number of related meanings in English. ... An audio filter is a type of filter used for processing sound signals. ... Loudness is the quality of a sound which is high in volume (amplitude, or sound pressure). ... Vibrato is a musical effect where the pitch or frequency of a note or sound is quickly and repeatedly raised and lowered over a small distance for the duration of that note or sound. ... Amplitude is a nonnegative scalar measure of a waves magnitude of oscillation, that is, magnitude of the maximum disturbance in the medium during one wave cycle. ... Tremolo is a musical term with two meanings: A rapid repetition of the same note, a rapid variation in the amplitude of a single note, or an alternation between two or more notes. ... Waveform quite literally means the shape and form of a signal, such as a wave moving across the surface of water, or the vibration of a plucked string. ... Sine waves of various frequencies; the lower waves have higher frequencies than those above. ... In musical terminology, tempo (Italian for time) is the speed or pace of a given piece. ... Synchronization is coordination with respect to time. ...

Electronic musicians use LFO for a variety of applications, ranging from adding simple vibrato or tremolo to a melody, to more complex applications such as triggering gate envelopes. Differences between LFO rates also account for a number of commonly heard effects in modern music - for instance, a very low rate can be used to modulate filter frequency, thereby providing the characteristic gradual sensation of the sound becoming clearer or closer to the listener. Alternatively, a high rate can be used for bizarre 'rippling' sound effects (indeed, another important use of LFO would be for various sound effects used in films). However, these effects are difficult to describe, instead they are more understandable simply when heard. For the album, see Sound Affects. ...

The British electronic music group LFO take their name directly from the concept of low frequency oscillation, its properties doubtless influential in their music production. LFO is an English techno group on the Warp Records label. ...