Since its invention in 1966, the wah-wah pedal has been instrumental in humanizing the sound of the guitar by altering the tone and frequency of its signal to mimic the human voice. Cry Baby: The Pedal That Rocks The World is a fascinating hour-long documentary that tells the story of the wah-wah pedal and its impact on contemporary music through the accounts of musicians, engineers and historians. From its technical evolution to its role in enabling greater creative expression in music, the film features interviews with icons like Eddie Van Halen, Slash, Buddy Guy, Art Thompson, Eddie Kramer, Dweezil Zappa, and Jim Dunlop.
(Source: brainpickings.org)