What are all those piano pedals for, and how did they get there? This article explores the pedals and their history.

The piano pedals have by no means remained constant throughout the history of the piano. Today we refer to the piano’s right pedal as “the pedal,” but the number and functions of the pedals have changed throughout the instrument’s history.

The right pedal is the sustain pedal, and it raises the dampers so that the sound can continue even when you let go of the keys. The sustain pedal actually started our life as a knee lever (around 1765) rather than a foot pedal. (Before that, the dampers were raised manually using hand stops, which sometimes required an assistant.) The pianist’s right knee would push up a lever built into the underside of the keyboard. This leads me to an embarrassing story which Jörg Demus shared with me:

The great German pianist Walter Gieseking was the first to record Mozart’s complete piano music. He noted that he had seen pianos of Mozart’s time in museums, and since they were lacking pedals, he decided to record Mozart’s complete piano music without using the pedal.

The young Paul Badura-Skoda (my own teacher), who in the 1950s pioneered the rediscovery of period pianos, wrote a letter to Gieseking thus:

Dear Maestro Gieseking, you are a very great musician. You are also great in stature. Had you bent over, you would have noticed that in place of a foot pedal, Mozart’s piano had a knee lever!

(I should note that whether or not to use pedal when playing Mozart is still debated amongst musicologists. However, there is sufficient evidence that his music should be played with pedal – and Mozart himself even wrote about how he loved the pedal on Stein’s pianos.)

The una corda pedal, or soft pedal, is the left pedal and it softens the sound in one of two ways. On upright pianos it moves the hammers closer to the strings so that the hammers move a shorter distance and hence strike the keys with less force. On grand pianos, the una corda pedal actually shifts the entire keyboard to the right by a few millimeters. This results in one less string being struck, and hence a softer sound.

Higher-end grand pianos have a middle pedal, which is known as the sostenuto pedal. This allows only those keys to continue to resonate which were held when the pedal was pressed. If you press a key, the dampers raise in order to allow that key’s strings to vibrate. Ordinarily, when we let go of a key, the dampers return to the strings, stopping them from vibrating and hence causing them to stop sounding.

If the right pedal (the sustain pedal) is held, all of the piano’s dampers are raised and any strings that happen to be overtones of the keys actually pressed (i.e., mathematically direct relatives) with vibrate in sympathy.

The sostenuto pedal, by contrast, allows only selective strings to vibrate. The sostenuto pedal acts like an invisible hand. If you press a key and then “capture” it with the sostenuto pedal. you’re free to move your hands elsewhere on the keyboard and the sostenuto pedal will continue to hold that key for you.

I’ve seen historical pianos with half a dozen or even more pedals. The remaining pedals created sound effects that sometimes imitated other instruments such as the bassoon, lute or even percussion!

In our day, the Australian-made Stuart piano has a fourth pedal. This pedal moves the hammers closer to the strings, just like the soft pedal on an upright piano.