How does a piano work?
Category: Miscellaneous

- Image via Wikipedia
How does a piano make noise? Well, as much as I like to imagine that there are little piano-gnomes that live behind my sheetmusic, sometimes it’s better to face reality. And in reality, how a piano works has a lot to do with physics and mechanics, and less to do with mythical creatures.
While the piano is often grouped in with percussion instruments, it actually depends on strings to make noise. The pitch of a string (that is, the high or low quality) depends on a string’s length and tension. The longer and looser the string, the LOWER the pitch will be. The shorter and tighter the string, the HIGHER the pitch will be. This makes a lot of sense if you think about sound as a series of vibrations. Long and loose strings will vibrate more slowly, so the resulting FREQUENCY of the note will be LOW. Short and tight strings will vibrate more quickly, resulting in a higher frequency, and therefore a higher note.
So, if you took a look at the inside of your piano, you would find a series of strings – each corresponding to a key on the keyboard. A keyboard with 88 keys will have 88 corresponding strings. So now that we know about the existance of the strings, how does the piano use them to make noise? With other stringed instruments the noise-production process is more obvious: You strum the guitar, stroke a violin with a bow, and pluck a harp. But in the piano, you press a key, a bunch of magic happens, and a sound comes out.
This “magic” is actually a complicated mechanism that translates the downward stroke of the key (or action) into a hammer striking a string. Rather than me explaining this mechanism to you, take a look at it here. You’re glad I didn’t explain it to you now, aren’t you? This mechanism varies depending on whether you have an upright piano or a grand piano. This is because the upright piano strings are strung vertically, while the grand piano strings are strung horizontally.
So we’ve made it to the point where we have sound. A little bit of sound, but sound nonetheless. If the piano were only to consist of keys, hammer, strings, and nothing else, your fortissimo’s would sound a little… pianissimo. That, my friends, is why we have a soundboard. Because nothing is worse than having your fortissimo sound like a pianissimo. Trust me. To combat that problem a soundboard collects the vibrations from the strings, and retransmits the sound, kindof like the body of an acoustic guitar.
The last thing I’m going to mention is the damper. It is a felted block that rests against the strings to stop their vibration. Without the damper in place, a key that is pressed will ring out until it gradually fades away. The damper absorbs the vibrations of the string so that it only sounds for a short time. The damper pedal (rightmost pedal) actually lifts the damper block from the strings so that the strings can ring out. Try it! Play a short note without the pedal, and then play the same note with the pedal depressed. You’ll notice that the note played while the pedal was down will last longer than the note played while the pedal was up.
That’s the piano in a nutshell. Now that the physics lesson is over, I’m going to resume my piano-gnome fantasies.




Posted on May 25th, 2010 by sharlene
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