What do the pedals on a piano do?

Question from Gemma Reed

When you press a piano key, a hammer inside hits the corresponding strings, just as a device called a damper is lifted. This enables the strings to vibrate, producing a sound before the key is released and the damper returns to its position, stopping the vibration.
Pressing the piano’s right-hand pedal keeps the damper off the strings, even after the key’s released, allowing the vibration to continue and the note to resonate. The middle pedal, called the sostenuto pedal, has a similar purpose, but only lifts the damper off the strings you’ve hit, enabling the effect to be controlled. 

Finally, the left-hand una corda pedal is used for a softer sound. Most treble keys of a piano are attached to three strings, but this pedal will cause the hammer to only hit two instead of all three at once.


Answered by Joanna Stass for Brain Dump in How It Works issue 96.

To feature in our Brain Dump section, send us your questions to [email protected] or message us on Facebook or Twitter


For more science and technology articles, pick up the latest copy of How It Works from all good retailers or from our website now. If you have a tablet or smartphone, you can also download the digital version onto your iOS or Android device. To make sure you never miss an issue of How It Works magazine, subscribe today!