A special type of timbre modifier module that accepts two signals as audio inputs and produces their sum and difference tones at its output, but does not pass on the frequencies found in the original signals themselves. This greatly increases the number of harmonics contained in the two sounds and introduces a gross nonlinearity, causing huge amounts of harmonic and intermodulation distortion. The ring modulator is used in the generation of electronic music, usually in conjunction with a lowpass filter which reduces the high-frequency roughness of the resulting metallic sound. It gets its name from its circuit configuration which is a circle, or ring, of four diodes. See also oscillator sync.