Twelfth Root Of Two Article Index for
Twelfth
Website Links For
Twelfth
 

Information About

Twelfth Root Of Two




The smallest interval in the equal tempered chromatic scale is a semitone, which is numerically equal to a multiplication with:

\sqrt {Link without Title} {2} or approximately 1.05946309436.

Since a musical interval is a ratio of frequencies, and the equal tempered chromatic scale is a way of dividing the Octave (which has a ratio of 2:1) into twelve equal parts, the semitone must be that ratio which when multiplied by itself twelve times will be equal to two. Therefore it is the positive real solution for x in the equation x^{12} = 2, or the twelfth root of two.


HISTORY


The twelfth root of two was first calculated accurately by Prince Chu Tsai-Yu of the Ming Dynasty . In 1596, he published a work, ''Lu Lu Ching I'' ("A clear explanation of that which concerns the ''lu'' ( Musical Pipes )"), which gave pipe lengths for 12-tone equal temperament "with absolute correctness to nine places". The calculation must have involved starting with the number 2 followed by at least 108 zeros, taking the square root twice, and then the cube root.

Prince Chu noticed the difference between his ideal mathematically-tuned ''lu'' and traditional pipes, which used a form of Pythagorean Tuning .


SEE ALSO



REFERENCES

  • From http://www.physlink.com/Education/AskExperts/ae165.cfm:

  • :"Mathematically, ... each successive pitch is related to the previous pitch by a factor of the twelfth root of 2. That is, the ratio between the frequencies of any two successive pitches in either standard is 1.05946309436."

  • Partch, Harry. ''Genesis of a Music''. Da Capo Press, 1974. ISBN 0-306-80106-X