Text: The vibration ratio or vibration fraction of an interval, is the ratio of the vibration numbers of the two sounds forming that interval. The vibration ratios of the principal music intervals have been exactly verified by Helmholtz's modification of the Double Syren. It may be shown, by means of this instrument, that the vibration numbers of the three tones of a Major Triad, in its normal position - G, E, C are as 4:5:6. Starting from this experimental foundation, the vibration numbers of all the tones of the modern scale can readily be calculated on any basis; and from these results, the vibration ratio of any interval used in modern music may be obtained. Vibration ratios must never be added or subtracted. To find the vibration ratio of the difference of two intervals, divide the vibration ratio of the greater interval by that of the smaller. To find the vibration ratio of any interval increased by an octave, multiply by 2/1; thus the vibration ratio of a Major Tenth is: 5/4 x 2/1 = 10/4 = 5/2.

See Also: INTERVAL

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