How Does An Acoustic Piano Work?

The inner workings of an acoustic piano are intricate, complex and without a real understanding and care of each part, could leave your piano suffering with a number of issues that won’t be identified until it’s too late. Today, we’re looking to break down the inner workings of your piano and begin to give you a basic insight into the kinds of things that you can expect to find, how to care for them and also how you can help keep your piano in the best condition possible.

If you have any questions regarding any of the pieces mentioned in this article, or think your piano in need of a little TLC, our team of expert piano technicians have been servicing pianos for over 160 years and are on hand to help!

How Does A Piano Make Its Sound?

The first thing that is crucial to understand is how a piano actually makes a sound. What actually happens when you hit a piano key is a little more complicated than you might think and something that many beginner players easily overlook. 

In the same way that a guitarist makes a sound by plucking or strumming a string, so do pianos (to an extent!) That may sound a little strange, but the sound of a piano comes as a result of what is known as a ‘hammer’, striking a string on the inside of a piano. Each of the 88 keys on the piano has its own set of strings and all of the keys are tuned to play a different note. This is why when we press multiple keys, we are able to begin creating chords, harmonies and other musical phenomena.

This of pressing a key, then moving the hammer is known as the piano action and when a hammer hits it’s respective string, it vibrates. This vibration then travels through the string and into the large wooden soundboard that amplifies the sound, giving you that warm rich authentic piano sound.

Now that you understand the basic mechanism of how a piano actually makes its sound. Let’s break down each piece a little farther.

The Hammers

A piano hammer is the mechanism used that will strike a piano string.  A key press results in around a 4.5x increase at the hammer end, meaning that pressing a key by 1mm means the hammer moves 4.5mm towards the string. In essence, this means that a harder hit will generally create a louder sound. This is where piano touch comes into play and opens up a whole world of possibility for pianists as you are able to create thousands of tiny nuances within every single note on your piano. 

Piano hammers are generally oval shaped and covered in a firm felt surrounding a wooden core and attached to a head moulding and a long pole known as a flange, as well as a number of other intricate parts to make sure the pianist gets the exact feel they are looking for. The hammers are so important, that even the different types of felt on the hammerheads and the types of wood used in the heads can generate completely different sounds.

Over time of course, as the hammers continue to strike the strings, it’s inevitable that there will be some wear and tear. This is why we generally recommend having your hammers ‘refaced’ every few years. After thousands of hitting in the same strings, the strings create grooves in the hammer head. These can be easily skimmed and sanded out by a piano technician and replaced to give your piano a new lease of life. Our piano technicians are able to safely remove each piano hammer and give it a much needed polish.

Piano hammers also come in a range of different sizes. You’ll generally find that larger (bass and tenor) hammers are found at the lower end of the instrument, with smaller hammers (treble) found at the opposite end. 

The Dampers


With all of these hammers striking away, without a mechanism in place, you’ll find that other strings will also begin to vibrate, especially when playing very fast or hard….

…That’s where the damper comes in! A damper is a small pad mechanism covered in felt that hangs above each piano string. A damper is also connected to each key and is moved in accordance with the hammer. When a key is pressed, the damper also rises, allowing the string to ring, when the key is released, the damper returns to the string, stopping the vibration and muting the sound.

A damper is a crucial component in your piano, if a key damper is not working, you will find that the note continues to ring even when you don’t want it to, which can completely ruin a melody or sound that you are trying to create.

You’ll also find that the dampers are also linked to your sustain pedal (also called damper pedal, loud pedal, or open pedal), which we’ll cover at the bottom of this article. When this pedal is pressed, all of the dampers in the piano rise, creating a longer lasting, echoing sound across the entire piano.

The Strings

Remember how we said each piano key is attached to a string? Whilst there are 88 keys on a piano, there are far closer to 230 piano strings inside of a piano. This is because many of the higher notes inside of the piano actually have 3 unique strings as when using the ‘soft pedal’ to make the sound quieter, the action in the piano is shifted over so that the hammer hits fewer strings (two or one). As they are generally thicker and stronger, lower notes have 2 strings, and the very low notes only have 1 string.

Because of the sheer number of strings, this is why piano tuning remains an incredibly complex job and requires years of training to ensure the correct sound is being made. We generally recommend having your piano tuned by a piano technician every 6 months.

Piano strings are made of a specialised type of wire to help cope with the heavy demand placed on them.  A high-carbon steel string is used and is so strong and thin that it actually has a number of other uses outside of pianos, including use in springs, surgical instruments and even in special effects for movies and theatre!

The bass strings on a piano are the same material at their core, but are wrapped with copper to add to their thickness, allowing a lower pitch to be produced without having too low a tension to play the correct note.

The Soundboard

Just as it says it’s name, the soundboard is the part of the piano which helps amplify your sound.Typically the soundboard is a large, thin wooden plate that is located on the underside of the piano for grand pianos, or on an upright piano, on the back of the piano.

When buying your piano, especially if it is a second hand piano, we would always recommend checking your soundboard for any cracks, holes, damp or damage as this can dramatically change the sound of your piano. Check out our second hand piano buyers guide here. At Millers, our technicians also offer an evaluation service to review your second hand piano, giving you full peace of mind when purchasing, along with a full report of recommended changes.

The Pedals

Finally we come to the pedals.

Most acoustic pianos generally have two or three pedals to be worked by the pianist’s feet. The right pedal is the sustaining pedal, as mentioned earlier, its role is to release the dampers on the keys to create a sustained sound, it is the most commonly used of the pedals.

The other two pedals can differ slightly depending on the piano and make. However generally speaking, the leftmost piano is the ‘soft’ pedal – this moves the hammers closer to the strings, or a little more towards the side to allow the music to be played at a more gentle tone, opening up small nuances within your music to create a more delicate feel.

The middle pedal is a little more variable, but generally speaking is used for lifting the dampers on the notes being played at that time in order to sustain a prolonged sound, on some pianos however, it may just lift the dampers on the lower notes. You can also read our full guide to piano pedals here.

We hope this simple guide has helped walk you through a little more on the anatomy of your piano and has given you a bit more of a basic understanding on maintaining the condition of your piano! Of course there are a lot more details that we could cover, but we’d be here all day. If you have any questions on your piano, or would like your piano to be tuned and serviced, our team of experts are on hand and eager to help! Get in touch today!

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