LFO may stand for low-frequency oscillation or low-frequency oscillator. Low-frequency oscillation refers to electronic audio signals that are below 20 Hz. These signals do not create an audible tone, but instead generate a pulsating rhythm. The rhythmic pulses that are created are used for the modulation of various audio equipment, such as delay lines and synthesizers. LFO is a common audio technique that is used to produce electronic music. It can be also be used to create effects, including tremolo, phasing, and vibrato.

The concept of low-frequency oscillation was introduced during the 1960s and 1970s. It appeared in different types of modular synthesizers before, and is now a part of some electronic musical instruments. Examples of modern electronic instruments which make use of LFO to enhance their ability to alter sound, include software synthesizers and samplers.

LFO can be routed to control the audio oscillator frequency, filter frequency, amplification, stereo panning, and the phase. When an LFO is routed to control the pitch, a vibrato is created. On the other hand, when it is used to modulate the volume or amplitude, a tremolo is generated.

Aside from the different routing options discussed above, there are also other controllable parameters that are present in the LFOs on sound modules and synthesizers. Some of these include various waveforms, tempo sync, and rate control.

Musicians make use of LFO for a variety of purposes. It is used to include a tremolo or a vibrato to a melody, control the arpeggiation rate, or trigger an envelope gate. A high LFO rate is used to create rippling sound effects that are normally used in movies, while a very low LFO rate may be used to modulate the cutoff frequency of a filter. By regulating a filter’s cutoff frequency, the sound becomes clearer and provides a sensation that the sound is closer.