Equal Temperament

You may know the famous Greek mathematician Pythagoras as the fellow that put forth the basic principles of geometry. He was also very interested in the science of music, among many other things. He knew, thousands of years ago, that a musical tone is created when something vibrates - a string, for example. He knew that if the same string vibrates two (2) times as fast (twice the frequency), the pitch of the note will be exactly an octave higher. He also knew that if the string vibrates three (3) times as fast (three times the frequency), the pitch will be an octave plus a fifth higher. He determined these things from experiments that he performed with strings. So he concluded that if the string vibrates one and a half (1½) times faster, the pitch will be just exactly a musical fifth higher.

Pythagoras was a very clever fellow, and he knew about The Circle of Fifths all those years ago. Being a good mathematician, he also realized that multiplying the frequency of a given starting note by 2 seven times will not produce exactly the same result as multiplying the same starting frequency by 1½ twelve times. He calculated that the frequency reached by ascending a perfect fifth twelve times is about 1% higher than the frequency reached by ascending seven octaves from the same starting note.
If you are a whiz at arithmetic, try working out the exact numbers.

Back in the eighteenth century piano tuners learned to tune the fifths on a piano (or on a harpsichord back in those days) about 1% small so that everything comes out just about right. This tuning trick is called Equal Temperament, because it allows the instrument to play equally well (and an equally tiny bit out of tune) in every key. The famous Baroque composer Johann Sebastian Bach loved this capability, and set about writing music in every possible key to take advantage of it. One very well-known set that you may be familiar with is usually called "The Well Tempered Clavier" in English. Bach's original German title is "Das Wohltemperierte Klavier".



Copyright © 2010 Cranbury Music
All rights reserved