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.
Some verticals have only two pedals, and a few (e.g., the Yamaha U3 and most BÃ¶sendorfers) have a true sostenuto mechanism. On older uprights and consoles the middle pedal is usually a bass sustain (acting like the right pedal but only on the bass register), or sometimes it's simply hooked to the left pedal lever and works the device that moves the hammers closer to the strings.