What Does The Middle Pedal On A Piano Do?

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What does the middle pedal on piano do?

It’s a question I’m asked almost constantly when speaking about pianos. Even those with good piano skill don’t have more than a cursory understanding. 

But it’s still important (and impressive) to be able to answer: 

What does the middle pedal on a piano do? 

The middle piano on the piano is most commonly the sostenuto pedal. This pedal sustains the notes being played while the pedal is pressed down, but notes played after are not held. Other common uses include practice pedal, silent system, and bass sustain pedal. 

This is complicated (not like knowing what the black keys on piano are), so be sure to read on for more details.

Why Are The Piano Pedals? 

Before we dig into what the middle pedal does on a piano, it may be helpful to learn about why we have piano pedals in the first place. 

In the early development of the piano (back in the 1700s), pianos were invented and quickly became popular.

The use of a hammering mechanism on strings gave the piano (called fortepiano) the ability to play a wide range of volumes (dynamics). It’s predecessor, the harpsichord, was incapable of such loud and soft ranges.

However, in order to stop all strings from ringing all the time, the piano used dampers to stop the string after the player lifted their hands off the keys. 

The solution of the time was called hand stops. Similar to organ stops, the piano stops would need to be pulled to sustain the notes and raise the dampers. 

This was inconvenient to create sustained sounds with complicated pieces. As the piano’s popularity rose, so did the music written for it. 

In the later 1700s, knee levers were invented and used. Mozart used them and reported favorably on them.

Shortly after this, the levers were moved towards the floor and became pedals. 

The sustain pedal and una chorda (soft) pedal were around at this time, though it took longer before the middle pedal settled on its most common use as sostenuto pedal. 

What Does The Middle Pedal On The Piano Do?

Into the 1800s, the middle pedal was in use. Some pianos of the time used many more pedals.

The middle pedal even at this time was the least used, and piano makers experimented with its purpose. 

In today’s pianos, the middle pedal will serve one of four uses, some more or less common than others. 

Sostenuto Pedal 

This is the most common use of the middle pedal. It’s found on almost all grand pianos and all digital pianos with a third pedal. 

The sostenuto pedal is a modified sustain pedal. 

In a nutshell, here’s what happens: 

  • You press and hold keys.
  • Then you press the sostenuto pedal.
  • The notes you were playing as you pressed the pedal are held over.
  • Any new notes you play are NOT held over while you keep the pedal down. 

This allows for interesting and sustained harmonies held while a melody moves around. This technique became more popular during the Romantic period.

Practice Pedal 

There’s a good chance if you have an upright piano, the middle pedal will instead serve as a practice pedal. This is the second most common use of the pedal. 

The idea is simple in its execution: press the practice pedal, make the piano softer. 

The way this works is quite clever. When the practice pedal is pressed, a felt rail activates between the hammers and the strings. 

Now, the hammers hit the strings through the felt, lessening the sound greatly.  

Silent System

This is a newer use for the middle pedal, and the least common. It essentially makes the piano an acoustic/electric piano. 

When you press the silent pedal, a bar drops in front of the hammers, preventing any connection with the strings. 

As the hammers strike the bar instead of the strings, the information is picked up digitally and put through an audio jack. 

This effectively makes the piano a digital keyboard and awesome for practicing without others hearing you. 

Though it’s called a silent system, it’s not truly silent. You’ll still hear the sounds of the hammers hitting the bar. 

Bass Sustain

The bass sustain is rare in modern day pianos and only pops up on special types of pianos and lower end grand pianos. 

The bass sustain pedal raises the dampers and lets the notes ring, just like the normal sustain pedal. But with the bass sustain pedal, only the lower notes are held over.

This use was more popular during the early versions of the middle pedal. Beethoven was known for playing around the middle pedal uses and supposedly used this one quite often. 

By sustaining only the lower pitches, it may make the piano sound a little more like an organ. The organist presses bass notes with their feet and can sustain them for a long period while melodies play over the top. 

The bass sustain pedal is a simple variant on this idea. 

Which Middle Pedal Do You Have?

In direct answer to your question, “What does my middle piano pedal do?”, we need to do a simple check. 

Follow these steps to figure it out: 

  1. Look for a headphone jack. 
    1. Don’t have one? Not a silent system. 
  2. Hold high notes. Press the pedal. Lift hand. 
    1. Do the notes sustain? If they do, not a practice pedal or bass sustain pedal. 
  3. Press one note. Press pedal. Lift hand, keep pedal down. Play another low note. 
    1. Do all notes sustain? You have a bass sustain pedal. 
    2. Does the first note sustain but not the others? You have a sostenuto pedal. 
  4. Play the same note loudly over and over. Press and lift the pedal. 
    1. Does the sound get quieter when the pedal is down? This is the practice pedal. 
image 4 types of middle pedals on piano infographic
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Sostenuto Pedal Vs. Sustain Pedal

With a better answer for “what does the middle pedal on piano do?”, we can look more closely at how the sostenuto (middle) pedal compares with the most common sustain (right) pedal. 

They’re similar in function, but different in execution. 

Sustain Pedal

The sustain pedal is kept on the right. When the pedal is pressed down, all dampers are lifted. 

The dampers are pads which stop the strings from ringing when the key is lifted. 

But with the sustain pedal pressed, the strings are left to ring. As long as the sustain pedal is pressed, all strings played will continue to ring. 

This is the most used pedal in piano playing. 

Sostenuto Pedal 

The sostenuto pedal also sustains (or holds) notes, but not all of them. It’s kept in the middle of the pedals. 

When you press keys, the specific strings’ dampers are lifted to allow the note to ring. The sostenuto pedal locks those dampers up and sustains only the notes you were playing when the pedal was pressed. 

As you play other keys, they function as if there was a pedal being pressed, but the originals are held as long as the sostenuto pedal is pressed. 

This pedal is rarely used, even by professionals. 

2 Pedal Piano

You may be wondering why not all pianos have 3 pedals. Well, the more pedals you have, the more mechanics inside the instrument. 

This takes up space and affects the sound. Many upright pianos won’t have the space for the middle pedal’s mechanism. 

Upright pianos that do have the space usually opt for the practice pedal use. 

Wait! If there’s only space for 2 pedals, which 2 will they choose?

Simply put, if there are 2 pedals, you’ll have the sustain on the right and the una chorda (soft) pedal on the left. 

Why? These just have the most use. 

One of my piano professors in undergrad described the use for me like this: 

For amateurs, the sustain will be used 99% while the una chorda will be used 1%. The sostenuto will never be used. And that’s OK. 

For professionals, depending on the style, the sustain is used 95%, una chorda is 4.9%, and the sostenuto is 0.1%. 

With this in mind, it’s easy to see why, when the chips are down, the sustain and una chorda pedals are the priority. 

How To Use Piano Pedals

Knowing the purpose of the pedals will help you determine when and how to use the pedals. Keep in mind, the sustain pedal will be used the vast majority of the time. 

Sustain pedal – Right

Press down the sustain pedal as you play. When the chords switch, lift and repress the pedal. 

Follow this rule for all your piano playing, and you’ll use the sustain pedal almost exactly right. 

Another strategy I encourage for my students is to hold the pedal down as they play until they notice the sound getting “muddy” or “crazy.” When you hear this, reset the pedal. 

And the next time you play this song, consider resetting the pedal a couple of beats before this happens again. 

Some music notation will mark how long to hold the pedal, but many will not. You have to learn to use your ears. 

Una Chorda (Soft) Pedal – Left

This makes the sound softer and simpler. Not by “dampening” the sound like a practice pedal will, but by cutting out one of the two strings vibrating (see how pedals work section below). 

Use this when you want a delicate and quiet sound. I encourage students to play around with this pedal to get used to its sound. 

When you’re more familiar with what it sounds like, then you have the experience to choose artistically when to employ it.

Sostenuto Pedal – Middle

Use the sostenuto when you hit a chord or sound you want to ring for a while other playing continues. The other playing would normally muddy up the sound, but now it won’t. 

Of course, no amount of dampening or sustaining will fix an out-of-tune piano. Keep it tuned regularly. 

Learn about how long it takes to tune a piano

Check out the sostenuto pedal in action with this video. 

How Does The Pedal On A Piano Work?

In this section, I’ll briefly go over how the piano pedals work to alter the sound they do. 

Sustain Pedal (Right)

When you press a piano key, two things happen:

  • The dampers are lifted off the strings you’re playing. 
  • A hammer strikes the strings (this is what makes the sound). 

When you lift your finger off the key, the dampers drop down to stop the sound.

The sustain pedal raises the dampers off all the keys for as long as you press the pedal. This makes any keys you play ring or sustain for much longer. 

Una Chorda (Left) 

The una chorda or soft pedal makes the sound softer and more delicate. Each note actually has two strings hit by the hammer. 

The una chorda pedal mutes one of the strings. Otherwise, the key functions the same.

This cuts the sound down and (I think more importantly) thins and purifies the sound. 

Sostenuto Pedal (Middle)

When pressed, the sostenuto pedal prevents the dampers from stopping the sound of the keys being played when the pedal is first pressed. 

As long as the pedal is down, these first notes remain locked open for sustained sound. Any notes played after the pedal is pressed continue to function as any other note normally would. 

Read the earlier section for more details.

Got an old piano you want to get rid of? Learn where to donate a piano. 

Conclusion

Now you know a little more about what the middle pedal on a piano does. 

The sostenuto pedal has an interesting use in holding over only the notes played as the pedal is pressed. Notes held down after the fact will not hold on to. 

You’ll be a genius now when people ask: “What is the middle pedal on a piano used for?”

After all, many professional level players don’t know or use it either. 

Interested in learning more about playing piano at any level?

Check out Flowkey, an online piano learning program with practice tools, comprehensive courses, and over 1,500 songs broken down for learning. 

Yes, this is an affiliate link, but I can’t stress how awesome these guys are. Seriously, check them out. 

Zach VanderGraaff

Zach VanderGraaff is a K-5 music teacher with Bay City Public Schools in Michigan. He's a Past-President of the Michigan Kodaly Educators and Executive Secretary of the Midwest Kodaly Music Educators Association.

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