Some electric guitars use a (misnamed) lever called a "tremolo arm" or "whammy bar" that allows a performer to lower or (usually, to some extent) raise the pitch of a note or chord, an effect properly termed vibrato or "pitch bend". This non-standard use of the term "tremolo" refers to pitch rather than amplitude. However, the term "trem" or "tremolo" is still used to refer to a bridge system built for a whammy bar, or the bar itself. True tremolo for an electric guitar, electronic organ, or any electronic signal would normally be produced by a simple amplitude modulation electronic circuit. Electronic tremolo effects were available on many early guitar amplifiers. Tremolo effects pedals are also widely used to achieve this effect. In acoustic instruments, for e.g. guitar, tremolo effect provides the sustenance of sound for a longer span.