What are Piano Pedals For?

A simple guide to what each pedal does...

When learning to play piano, you generally have enough to contend with dealing with the keys, so the pedals tend to come into things a bit later. But, if you look at them with the trepidation of a person who has just been sat in the pilot’s seat of an airliner, don’t panic. They’re all pretty straightforward – hey, we’re musicians, not astronauts, after all…

Here’s a guide to what each of the pedals actually do, from right to left- you’ll never wonder ‘what do the pedals on a piano do?’ again…

The Sustain Pedal 

The sustain pedal (the rightmost pedal) is the most frequently used of all pedal, and is also the most essential to playing certain pieces. This is why sustain pedal inputs feature even on beginner level home keyboards.

To understand what it does, it’s worth considering the mechanics of how an acoustic piano works. Essentially, a piano consists of a series of strings, which are hit by hammers when keys are pressed, causing them to ring. When the key is released, the hammer returns to its place, resting on the strings, causing the note to stop ringing.

To prevent strings from other (un-played) notes resonating when notes are hit, a damper bar sits on the strings, keeping those strings deadened.

When the sustain pedal is depressed, this damper bar is lifted. The result is that notes will continue to ring after keys are released- i.e. they sustain.

A side effect of this on an acoustic piano is that the strings of other, un-played notes will also resonate gently, adding richer harmonics to the overall sound. This is known as sympathetic resonance, and many digital pianos now replicate this effect.

The Sostenuto Pedal 

Notated S.P., Sost. Ped., or ThP

Of all of the typical pedals on a piano, the sostenuto (middle pedal) is the one that tends to cause the most confusion. However, it is similar to the sustain pedal, in a sense. When depressed, only the notes that are being played at the point the pedal is used will sustain, whilst notes played after this will not. The sustained notes will hold until the pedal is released.

This enables the player to hold bass notes or chords, whilst playing staccato melodies over the top, for example.

The Una Corda Pedal 

Notated Una Corda, with Tre Corde or Tutte Le Corde to release pedal.

The leftmost pedal is the Una Corda pedal, which is sometimes known as the soft pedal. Again, to understand what this does, it’s worth taking a look at how an acoustic piano works. The strings on an acoustic piano are usually grouped into threes for each note, and tuned in unison to create a richer fuller tone (this is also the reason that acoustic pianos sound so dreadful when out of tune). When a key is pressed, the hammer normally hits all of these strings simultaneously.

When the una corda pedal is depressed on a grand piano, the internal piano action is shifted to the right, such that the hammers hit only two strings, resulting in a softer sound.

Historically, this pedal would result in the hammers hitting only one string (hence the name, meaning ‘one string’)- nowadays, due to the space constraints within piano cabinets, two strings are hit. This changes both tone and volume.

In an upright piano, there is even less physical space. As a result, the una corda pedal works by moving the hammers closer to the strings. This results in lower volume, but without altering overall tone.

Like riding a bike, or driving a car, understanding how to use the pedals takes a bit of time and practice. However, knowing what they do is the ideal place to start, and, once you’ve got the hang of using them (like riding a bike), you’ll never forget.