Diagram of normal sinus rhythm as seen on ECG. In atrial fibrillation the P waves, which represent depolarization of the top of the heart, are absent.
The wah-wah pedal is based on a simple concept but its effect is far more dramatic. Using a powerful filter to sweep through a broad frequency spectrum, the wah pedal boosts and exaggerates specific tones. Creating sounds that range from thick, flubbery bass to scratchy, stinging treble.
The stock wah pedal has been around since at least the early 60's. While there is a persistent rumor that an early version of a wah mechanism was found in the wreckage at the Roswell crash site, I can categorically state that the government says that this is nonsense, and that no such thing happened.