Hearing Fractions
- instruments vibrate the harmonic series -

What does a violin string look like when it vibrates to make sound?  How about a column of air inside a trumpet?

In this video, Phil's daughter, Sarah, shows how instruments vibrate in fractions called the harmonic series.  You will see and hear these harmonics on a string (i.e., violin), and an open-end tube (i.e., her trumpet).  She even includes a popular bugle call, or a melody, made up entirely of these notes.

Press play on the video below.  Notice how the string plays a low pitch, while it vibrates slowly as one whole. Keep listening as it divides into two halves, three thirds, four fourths, etc.  What happens to the pitch when the vibrations get shorter?  Does the pitch sound lower or higher?  What happens to the speed of the vibrations as they get shorter?  Do they get slower or faster?  Keep watching to see if a column of air inside a tube works the same way.

When you hear an instrument play music, you're hearing fractions!

 

 

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