<P> It is common to find uprights and even grand pianos that lack a middle pedal . Even if a piano has a middle pedal, one cannot assume it is a true sostenuto, for there are many other functions a middle pedal can have other than that of sostenuto . Often an upright's middle pedal is another half - blow pedal, like the one on the left, except that the middle pedal will slide into a groove to stay engaged . Sometimes, the middle pedal may only operate the bass dampers . The middle pedal may sometimes lower a muffler rail of felt between the hammers and the strings to mute and significantly soften the sound, so that one can practice quietly (also known as a "Practice Rail"). True sostenuto is rare on uprights, except for more expensive models such as those from Steinway and Bechstein . They are more common on digital pianos as the effect is straightforward to mimic in software . </P> <P> Among other pedals sometimes found on early pianos are the lute stop, moderator or celeste, bassoon, buff, cembalo, and swell . The lute pedal created a "pizzicato - type sound". The moderator, or celeste mechanism used "a layer of soft cloth or leather...interposed between hammers and strings to give a sweet, singing and muted quality". According to Good, "(the piece of leather or cloth was) graduated in thickness across its short dimension . The farther down one pushed the pedal, the farther the rail was lowered and the thicker the material through which the hammer struck the strings . With the thicker material, the sound was softer and more muffled . Such a stop was sometimes called a pianissimo stop ." </P> <P> The moderator stop was popular on Viennese pianos, and a similar mechanism is still sometimes fitted on upright pianos today in the form of the practice rail (see Sostenuto pedal, above). Joseph Banowetz states that for the bassoon pedal, paper or silk was placed over the bass strings to create "a buzzing noise that listeners of the day felt resembled the sound of the bassoon". The buff stop and cembalo stops seem to be similar to each other in method of manipulation and sound produced . The buff ("leather") stop used "a narrow strip of soft leather...pressed against the strings to give a dry, soft tone of little sustaining power". The cembalo stop pressed leather weights on the strings and modified the sound to make it resemble that of the harpsichord . Johannes Pohlmann used a swell pedal on his pianos to raise and lower the lid of the piano to control the overall volume . Instead of raising and lowering the lid, the swell was sometimes operated by opening and closing slots in the sides of the piano case . </P> <P> Often called "the father of the pianoforte", Muzio Clementi was a composer and musician who founded a piano - building company, and was active in the designing of the pianos that his company built . The Clementi piano firm was later renamed Collard and Collard in 1830, two years before Clementi's death . Clementi added a feature called a harmonic swell . </P>

What are the three pedals for on a piano