Why Do Pianos Have Pedals & How Do The Pedals Work?

When looking at a piano, you might have noticed a few pedals but were unsure of what they did. Well, you have come to the right place. Below we will walk you through everything you need to know about piano pedals.

Why do pianos have pedals, and how do the pedals work? Piano pedals are used to enhance or alter the music being played in some way when pressed down. Though different, all the pedals have a common theme of altering the way the hammers or the dampers work to affect sustain, tone, volume and more.

In this article, we'll discuss what pianos have pedals and how these pedals work.

Related My New Microphone articles:
 Top 11 Benefits Of Learning & Playing Piano
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Top 11 Best Acoustic Piano Brands In The World
Top 9 Best Digital Piano Brands In The World

Why Are There Pedals On A Piano?

Piano pedals are used to modify the musical tone or feel in some way. They're used to enhance the music being played by offering various alterations to the piano's dynamics, tonality, and volume. They do so by affecting the mechanism by which the piano produces sound. That is, the way the keys interact with the hammers and the way the hammers interact with the strings.

The sustain pedal, for instance, can be used to help the musician achieve smoothness in a piece of music by allowing notes to ring out even after we remove pressure from the key. This helps tie together chords and build stronger, more expressive harmony.

To put it another way, imagine someone is singing a smooth scale – with one note seamlessly transitioning to the next. After a certain amount of notes, the person has to take a breath in, causing a break in the “smoothness” of the running octave.

In parallel, the sustain pedal fills in the gaps, smoothing the transitions between melody lines or chords. The sustain pedal is the right pedal in both an upright and grand piano and is an excellent instrument for achieving legato.

To learn more about upright and grand pianos, check out my article What Are The Differences Between An Upright And A Grand Piano?

This is especially true when one has to play notes or chords that require your hand to jump from one position to another.

The practice pedal, sometimes known as the muffler pedal, is the middle pedal found in an upright piano. If, however, you do not have this pedal on your piano, it is in no way a cause for concern. Many upright pianos are built without the middle pedal.

The names ‘practice pedal' and ‘muffler pedal' offer you a hint as to what this pedal does. This pedal significantly reduces the piano's volume.

Thus, this pedal is frequently used to allow musicians to practise the piano when they otherwise would not be able to play at maximum volume, for instance, during late-night practice.

The soft pedal is the left pedal of an upright and is used during more delicate parts in music to produce a peaceful atmosphere or intimate feeling on the piano. In addition, it helps to create a clear distinction between soft dynamics.

A grand piano's middle pedal is called a sostenuto pedal. Through the use of this pedal, the music takes on an interesting dynamic. Only specific, selected notes are sustained by the sostenuto pedal, leaving other sounds relatively untouched.

This means you can sustain notes or a chord while simultaneously playing a staccato melody line, for example.

The shift pedal, also known as the una corda pedal, is the left pedal of a grand piano. This pedal has two functions: changing the volume and altering the instrument's timbre.

On older pianos, the una corda pedal creates a substantial timbre shift. However, due to the way modern pianos are built, the timbre change on modern pianos is generally designed to be subtle.

How Do Piano Pedals Work?

In this section, we'll discuss how different piano pedals work, from left to right. Note, once again, that different styles of pianos will have different labels and functions for their pedals, so we won't find all of the pedal types listed below on any given standard piano type.

The piano pedal types we'll focus on understanding are as follows:

How Do Sustain Pedals Work On Piano?

The sustain pedal, which is the right pedal on both an upright and grand piano, works similarly. There are dampers, strings, and hammers inside the piano, among other mechanisms.

The dampers are made of cloth or felt and function as a muting mechanism by preventing the strings from vibrating. For example, when a key is pressed, the damper for that key lifts away from the string.

The hammer will then strike the string causing the string to vibrate. The vibration of the string is what creates a sound. When the finger is lifted off the key, the damper returns to its original position, immediately stopping the sound.

So, when you depress the sustain pedal, the damper bar raises away from the strings and remains in that position until the pedal is released. As a result, the string will continue vibrating even after releasing your finger from the key.

On an acoustic piano, using a sustain pedal allows the notes to softly resonate with other strings, giving richer harmonics to the overall sound.

How Do Muffler Pedals Work On Piano?

When you depress the muffler pedal, a thin piece of felt is dropped between the hammer and strings. As a result, since this piece of felt is located between the mechanisms, the full effect of the hammer striking the strings will not be achieved.

Thus, using the practice pedal will considerably reduce the volume. In most cases, there is usually a groove located next to this pedal that will allow you to lock the pedal into place.

How Do Soft Pedals Work On Piano?

When the soft pedal is depressed, all the hammers are moved closer to the strings. This reduces the loudness by allowing the hammers to generate less velocity before striking the strings.

However, the full effect of this pedal can be best heard when already playing softly as the dynamic of the soft range is increased.

To learn more about volume control on pianos, check out my article Top 8 Methods To Make A Piano Quieter.

How Do Sostenuto Pedals Work On Piano?

To use the Sostenuto pedal, you must first play a note or chord and then press down on the Sostenuto pedal while playing those notes. Doing so will keep the dampers raised away from only those selected notes.

Any notes played after pushing the pedal down will not have the dampers raised away from the strings. Thus, any notes played after the pedal is pushed down will not be sustained.

How Do Shift Pedals Work On Piano?

The shift pedal, also known as the una corda pedal, shifts the whole action assembly to the right. As a result, the treble section's hammers will only hit two strings instead of three.

Additionally, the hammers in the bass section will strike a different part of the string due to the shifting of the action. This shifting of the assembly will is what causes a change of timbre.

What About Digital Piano Pedals?

Digital Pianos often come with single or triple-pedal units that connect to a control voltage port, often labelled as “sustain” for single-pedal units.

In the case of the digital sustain pedal, which is by far the most common, the pedal affects the envelope of the voice (sampled or synthesized) of the triggered key. With digital pianos, there are no hammers and no strings. Rather, each key triggers a digital note (often a sample but sometimes a synthesized waveform).

The volume over time of each note is governed by what's known as an envelope. Envelopes have 4 basic parts, often referred to collectively with the initialism ADSR:

  1. Attack: the time the audio takes to go from zero amplitude to peak amplitude as the note is played. This ties in closely with the transient.
  2. Decay: the time the audio takes for the subsequent run down from the attack level/amplitude to the designated sustain level/amplitude.
  3. Sustain: the level of the sound/amplitude after the attack and decay, which is maintained until the key is released.
  4. Release: the time taken for the level to decay from the sustain level to zero after the note is released.

When the digital sustain pedal is engaged, a triggered note will run through its attack and decay portions and remain in the sustain portion of its envelope until the sustain pedal is disengaged, when it will enter the release portion of the envelope and fade out.

The note could be cut short if the instrument runs out of polyphonic voice, which is common in synthesizers but not digital pianos, designed to mimic their acoustic counterparts' one-voice-per-key polyphony.

Related article: What Are The Differences Between Synthesizers And Pianos?

These digital sustain pedals are pretty inexpensive, like this option from Amazon Basics (link to check the price on Amazon). As I just alluded to, these pedals also generally work with synthesizers and also work with MIDI controllers. They typically connect via a 1/4″ TS jack.

Note that these pedals can typically be switched to reverse polarity, meaning that we can choose whether the “sustain” is on when the pedal is pressed down or when the pedal is in its neutral position (not pressed down).

Some digital pianos, like the Korg B2SP (link to check the price at Sweetwater), have more than just a sustain pedal. In this case, the B2SP has Damper, Soft and Sostenuto pedals in a 3-pedal unit. The B2SP is also supplied with a sturdy, piano-style metal sustain pedal.

Korg B2SP

Korg is featured in other top brand articles at My New Microphone. Check out these articles here!

These other pedals work by manipulating the envelope and the waveforms of the individual voices of the digital pianos. The tonality can be altered with EQ, while the effect of dampening can be achieved by altering the envelopes.

Related articles:
Top 9 Best Digital Piano Brands In The World
Are Acoustic Or Digital Pianos Better? Pros And Cons Of Each


Piano pedals are quite useful in the hands of musicians. They add exciting dynamics to the music or simply help the music practice without disturbing their neighbours. These piano pedals have definitely earned their place on the instrument.

This article has been approved in accordance with the My New Microphone Editorial Policy.


Arthur is the owner of Fox Media Tech and the author of My New Microphone. He's an audio engineer by trade and works on contract in his home country of Canada. When not blogging on MNM, he's likely hiking outdoors and blogging at Hikers' Movement (hikersmovement.com) or producing music. For more info, please check out his YouTube channel and his music.

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