Low-frequency oscillation

More recently other electronic musical instruments, such as samplers and software synthesizers, have included LFOs to increase their sound alteration capabilities.

The frequencies generated by LFOs are used as control signals which modulate another component's value, changing the output sound without introducing another source.

Also like a standard oscillator, LFOs can incorporate any number of waveform types, including user-defined wavetables, rectified waves and random signals.

They may be used to add simple vibrato or tremolo to a melody, or for more complex applications such as triggering gate envelopes, or controlling the rate of arpeggiation.

A very low rate can be used to modulate a filter's cutoff frequency, thereby providing the characteristic gradual sensation of the sound becoming clearer or closer to the listener.