A variety of mechanical
vibrato systems for guitar have been developed since the 1930s. They are used to add
vibrato to the sound by changing the
tension of the strings, typically at the
bridge or
tailpiece of an
electric guitar using a controlling
lever (often referred to as a
whammy bar,
vibrato arm/bar, or
tremolo arm/bar). The lever enables the player to quickly vary the tension and sometimes the length of the strings temporarily, changing the
pitch to create a
vibrato,
portamento or
pitch bend effect.