A device that accepts and processes two input signals in a particular way. The output signal does not contain any element of the original input signals but instead comprises new frequencies based on the sum and difference of the input signals' frequency components. The best known application of Ring Modulation is the creation of Dr Who’s Dalek voices, but it may also be used to create dramatic instrumental textures. Depending on the relationships between the input signals, the results may either be musical or extremely dissonant - for example, ring modulation can be used to create bell-like tones. (The term 'Ring' is used because the original circuit which produced the effect used a ring of diodes.)