Science and music / [by Sir James Jeans].

  • Jeans, James, 1877-1946.
Date:
1947
Catalogue details

Licence: In copyright

Credit: Science and music / [by Sir James Jeans]. Source: Wellcome Collection.

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    instance, if the force repeats itself 100 times a second, the simple harmonic constituents of the force will repeat them¬ selves 100, 200, 300, etc., times a second. If the structure has free vibrations of frequencies 100, 200, 300, etc., these will be set vibrating strongly by reso¬ nance, while any vibrations of other frequencies that the structure may possess will not be set going in any appre¬ ciable strength. In other words, a disturbing force only excites by resonance the “natural harmonics55 of a tone of the same period as itself. This, as we shall see later, is a result of great importance to music in general. Amongst other things, it explains why the stretched string has such outstanding musical qualities; the reason is simply that its free vibrations coincide exactly in frequency with the natural harmonics of its fundamental tone, so that when the fundamental tone is set going, the harmonics are set going as well. Timbre and the Harmonic Analysis of Sound By timbre is meant the distinguishing or characteristic quality of a sound; it is by their timbre that we recognise an instrument, a voice or the quality of an organ-stop, regard¬ less of the pitch or intensity of the note it is sounding. The investigations of Helmholtz proved that the timbre of a sound is determined by the proportions in which the various natural harmonics are heard in it. It is obvious that something of this kind must be true. We know, for instance, that the more we hear of the higher harmonics in any sound, the farther we get away from the dull quality of the tuning-fork, which is characterised by a