A device that linearly shifts all the frequencies of a complex input signal. Also called a spectrum shifter. All frequency components are shifted linearly, i.e., by the same number of Hertz, in contrast to a pitch-shift caused by changing the speed of a tape-reco. In such a pitch-shift, all the frequency components are shifted by a constant percentage, and therefore, high frequencies are shifted proportionally more than lower ones. A pitch-shift-by-speed change thus preserves all the musical intervals between components. A true frequency shifter, in contrast, destroys the harmonic relationships between the components. The sound of a consonant musical tone becomes disconsonant or clangorous or harsh, depending on the amount of shift. Frequency shifters are used in electronic music synthesizers for special effects.