Piano
On pianos with three pedals, the pedal in the middle does different things on a grand and upright piano. On a grand piano, it is the sostenuto pedal, and is pressed with the pianist's left foot. Like the right pedal, it keeps the sound going, but only on the notes that are being played at the moment when the middle pedal is pressed down. This makes it possible to keep one chord going while playing other notes that will not carry on. All concert grand pianos have a sostenuto pedal, and some modern upright pianos do as well. The middle pedal on some upright pianos is not a sostenuto pedal at all, but a practice pedal. It places a piece of cloth in front of the strings, making the sound very quiet so that a pianist can practice without disturbing other people. The practice pedal can usually be pressed down and put in a slot so that it will stay in place.