How does a
PIANO WORK
For a note to be played on the piano, it doesn’t require much effort – you just pick the key you want and you press it. Very different to an instrument like the trumpet or the violin, which requires a lot of time and persistence to achieve the desired sound. There would be many parents who are thankful for the fact that when their child starts learns the piano, it means there will not be any screechy, pitchy and horrible noises involved in the process. But how is the piano’s sound consistently clear and beautiful (unless it needs a tuning, if so see here)? Understanding how an upright piano works will give you further insight into how amazing this instrument truly is.
This is what an upright piano looks like with its covers off:
Hammers
So how do the strings vibrate? Each key is connected to a hammer so that when the key is pressed, the hammer hits the strings to cause it to vibrate. The hard you press the key, the more force the hammer uses producing a louder sound. You can actually press the key so slowly and gently that the hammer is unable to cause any sound.
As soon as the hammer is used, it returns to its resting position to allow the strings to freely sound.
They are made from wood with a thick felt covering.
SOUNDBOARD
Without the soundboard, the sound caused by strings would be too quiet to hear and so it is the soundboard’s job to work in the same way as an amplifier would. But there is so much more to it being just a piece of wood as it needs to be flexible enough to vibrate with the strings, yet strong enough to support 200+ strings. Piano builders a type of timber called ‘tone wood’ recognised for its acoustical properties. The most common type of tone wood used in pianos today is spruce. Cheap pianos use plywood with a spruce veneer as it is easier and cheaper to make but the sound quality suffers greatly. The best soundboards are produced from the oldest spruce trees grown in the coldest climates, that once cut, are naturally dried for several years. Great lengths must be taken to carefully cure the wood and craft it in such a way that it will sustain the tension for the life of the piano. And after all that, it is generally put against the wall, never to be seen. In the harsh Australian climate, soundboards are constantly moving from absorbing moisture in the humid months and drying out in the drier months. It is this expanding and reducing that causes the strings to move and become out of tune. The best time to tune your piano is a month or so after each weather change.
DAMPERS
I am sure you have noticed that when you push a key you can control how long it will sound for. You can create a short, sharp sound by letting go of the key as soon as you press it, as well as holding the key to let the sound ring. This is all to do with the dampers. When the piano is at rest each damper is in contact with its corresponding string. When a key is pressed the damper lifts at the same time the hammer strikes to allow the string to vibrate. Letting go of the key will allow the damper to return to its original position. Interesting fact - the highest strings do not usually need dampers as the strings are so short they do not vibrate for very long.
When you press the sustaining pedal (the one on the right) it lifts all the dampers so when a key is pressed, all the string vibrate to create a bell like sound. Once the pedal is released the dampers silence each string.
Frame
The frame holds everything together. It is the only thing connected to the soundboard. Made from cast iron it is subjected to as much as 20 tons of pressure caused by the string’s tension (30 tons for a grand piano). To be able to handle that type of pressure, the frame is pretty heavy weighing up to 100 kilos. With upright pianos weighing between 170 to 270 kilos, the frame takes up a huge chunk of the weight.
Caring for your piano
As you can see, there is many parts in the piano that work together to create sound from a simple touch. It is also easy to see why pianos are so expensive, thus it is very important to care for your piano with regularly visits from your piano technician and placing it in the best location in your house (up against an exterior wall away from sunshine, drafts, heaters/fireplaces and on a rug if the piano is placed on the tiles).
STRINGS
A piano’s sound is created by the strings vibrating. The majority of the keys have three strings which gives it its full, rich sound. Imagine a guitar plucking a note then adding two more guitars plucking that same note. At some point in the bass each note only has 2 and then eventually 1 because the strings become thicker. You can see the difference in thickness when comparing them to the higher strings. It is the same on any instrument with strings – the thicker the string, the lower the sound. You might also notice that you cannot see the highest strings under the keyboard as high strings are not only thinner, but shorter. At the top of each string is its tuning peg. This is where your piano technician will use a tuning tool to tighten the strings, putting the piano back ‘in tune’.