Wah-wah Pedal

A wah-wah pedal (or just wah pedal) is a type of guitar effects pedal that alters the tone of the signal to create a distinctive effect, mimicking the human voice. The pedal sweeps the peak response of a filter up and down in frequency to create the sound (spectral glide), also known as "the wah effect." The wah-wah effect originated in the 1920s with the crying tone that a muted trumpet or trombone produced, but became an expressive tool in its own right. Wah-wah effects are used when a guitarist is soloing, or creating a "wacka-wacka" funk styled rhythm.