Pianos normally have pedals located under the keyboard that are operated by the performer's foot and effect the sound. There are typically two pedals with the larger pianos having a third pedal in between the damper pedal on the right and the soft pedal on the left. The middle pedal is known as the sostenuto pedal. Depressing this pedal will dampen only the notes that have been struck. The indication for the sostenuto pedal is the letters " S.P. " below the notes followed by a line slanted up with a downward line on the end to indicate the release of the pedal.See also S.P. .third pedal on a piano. A real sostenuto pedal lifts the dampers that are already off due to their keys being held down. Some pianos have a third pedal that lifts the dampers off the bass strings, while maintaining clarity in the upper registers.