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 Fazioli concert grand piano model F308 includes a fourth pedal to the left of the traditional 3 pedals. This pedal acts similarly to the half-blow pedal on an upright piano, in that it collectively moves the hammers somewhat closer to the strings to reduce the volume without changing the tone quality, as the una-corda does.