The Mysterious Middle Pedal

Most pianos made within the past century have three pedals. The left and right pedals functions are well known, but what about the middle pedal? What does it do? For many players, it is a bit of a mystery.

The pedal furthest to the right (the damper/sustain pedal) is no mystery at all - it raises the dampers on all strings and causes those struck by hammers to resonate freely, as well as allowing surrounding strings to resonate in sympathy. This allows notes to be sustained and ring for a long time. All pianos function this way.

The pedal on the far left is almost always a soft pedal of some sort, however it has a little more variety as the mechanical function varies between upright pianos and grand pianos. In upright pianos, the left pedal moves the hammers closer to thew strings, thus a quieter sound.

In grand pianos, the left pedal shifts the entire piano action to the right, so that the piano hammers only strike two of the three strings which creates a much softer, mellower tone.

This brings us to the middle pedal - the mystery pedal. Unlike the damper and soft pedals, the middle pedal can have radically different functions from piano to piano.

In high-quality grand pianos, the middle pedal - the sostenuto - will keep the dampers raised on any note currently being played when the pedal is depressed. This is especially useful when the music calls for a note or chord to be sustained (usually in the bass) while another figure is played above it. Thus the pianist can sustain a chord while subsequent material, such as a scale, stays clean and unsustained.

A popular example of where such a pedal would be used is in Debusy's Clair de lune from the Suite Bergamasque. In the score below, the middle pedal would be depressed at the start of each sustained bass note:

On most other grand pianos, and in some upright pianos as well, that middle pedal will raise all of the dampers on the bass bridge. This is easier and less expensive to produce from a manufacturing point of view, and is a good substitute for the sostenuto pedal found in high-quality grands. This is because in most cases this function is used with bass notes, like we see with the Clair de lune example above.

Unlike grand pianos, there is significant variation in the function of the middle pedal in upright pianos.

In some newer uprights, the middle pedal serves as a practice pedal. A thick piece of felt is lowered between the hammers and the strings, drastically reducing the volume of the piano (see example below). This is great for pianos in places like apartments, where the otherwise powerful sound of a piano would be unappreciated by neighbors.

In other uprights, the middle pedal moves the hammers closer to the strings. In theory, this allows for more flexibility in dynamics. In practice, the difference in sound is so subtle, it is almost completely unnoticeable. While I still run into this from time to time with older upright pianos, newer models don't incorporate this function.

One exotic function I encounter from time to time is the mandolin pedal. The middle pedal lowers a strip of felt with metal strips attached to the ends. (See picture below) This creates a metallic, twangy, mandolin-like effect.

With still other uprights, the middle pedal is simply attached to the same mechanism as the far-left pedal. So it functions simultaneously with the left pedal and is essentially there for looks.

And occasionally, I encounter pianos that have a middle pedal that simply isn't attached to anything at all! Many piano manufactures that make more affordable upright pianos add these dummy pedals so that their piano don't look like they are "lacking" some important feature.

And of course, some upright pianos don't even have a middle pedal at all.

Now you're probably wondering what your middle pedal does. The most common design lifts just the bass dampers, so anything played in that range is sustained, and scales will sound muddy. Another way to tell what is going on is to take of the front panel and see what happens when you press the pedal.

And if your middle pedal isn't working, contact us at and we can get it working again!

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