On the sensations of tone as a physiological basis for the theory of music / by Hermann L.F. Helmholtz ; translated, thoroughly revised and corrected, rendered conformable to the 4th (and last) German edition of 1877, with numerous additional notes and a new additional appendix bringing down information to 1885, and especially adapted to the use of musical students, by Alexander J. Ellis.

  • Hermann von Helmholtz
Date:
1895
Catalogue details

Licence: Public Domain Mark

Credit: On the sensations of tone as a physiological basis for the theory of music / by Hermann L.F. Helmholtz ; translated, thoroughly revised and corrected, rendered conformable to the 4th (and last) German edition of 1877, with numerous additional notes and a new additional appendix bringing down information to 1885, and especially adapted to the use of musical students, by Alexander J. Ellis. Source: Wellcome Collection.

    34/604 (page 10)
    FORCE, PITCH, AND QUALITY. PART 1. The process which goes on in thc atmosphoric ocean about us, is of a precisely similar nature. For the stonc substitutc a sounding body, which shakes the air; for the chip of wood substitute the human ear, on which impinge the waves of air excited by the shock, setting its movable parts in Vibration. The waves of air proceeding from a sounding body, transport the tremor to thc human ear exactly in the same way as the water transports the tremor produeed by the stone to the floating chip. In this way also it is easy to see how a body which itself makes periodical oscillations, will necessärily set the particles of air in periodical motion. A falling stone gives the surface of the water a single shock. Now replace the stone by a regulär series of drops falling from a vessel with a small orifice. Every separate drop will excite a ring of wave, each ring of wave will advance over the surface of the water precisely like its predecessor, and will bc in the same way followed by its snccessors. In this manner a regulär series of concentric rings will be formed and propagated over the surface of the water. The number of drops which fall into the water in a second will be the number of waves which reach our floating chip in a second, and the number of times that this chip will therefore bob up and down in a second, thus executing a periodical motion, the period of which is equal to the interval of time between the falling of consecutive drops. In the same way for the atmosphere, a periodically oscillating sonorous body produces a similar periodical motion, first in the mass of air, and then in the drumskin of our ear, and the period of these vibrations must be the same as that of the Vibration in the sonorous body. Having thus spoken of the principal division of sound into Noise and Musical Tones, and then described the-general motion of the air for these tones, we pass on to the peculiarities which distinguish such tones one from the other. We are acquainted with three points of difference in musical tones, confining our attention in the first place to such tones as are isolatedly produeed by our usual musical instruments, and excluding the simultaneous sounding of the tones of different instruments. Musical tones are distinguished:— 1. By their force, 2. By their pitch, 3. By their quality. It is unnecessary to explain what we mean by the force and pitch of a tone. By the quality of a tone we mean that peculiarity which distinguishes the musical tone of a violin from that of a flute or that of a clarinet, or that of the human voice, wlien all these instruments produce the same note at the same pitch. We have now to explain what peculiarities of the motion of sound corresporid to these three principal differences between musical tones. First, We easily recognise that the force, of a musical tone increases and dimi- nishes with the extent or so-called amplitude of the oscillations of the particles of ^ the sounding body. When we strike a string, its vibrations are at first sufficiently large for us to see tliem, and its corrosponding tone is loudest. The visible vibrations become small er and smaller, and at the same time the loudness diminishes. The same observation can bc made on strings excited by a violin bow, and on the reeds of rced-pipes, and on many other sonorous bodies. The same conclusion results from the diminution of the loudness of a tone when we increasc our distance from the sounding body in thc open air, although the pitch qnd (piality remain unaltered ; for it is only the amplitude of the oscillations of the particles of air which diminishes as their distance from the sounding body increases. Hence loudness must depend on this amplitude,' and none other of the properties of sound do so.* ■ ‘ . * Mechanically the force of the oscillations no mcasure can be found for the intensity of for tones of different pitch is measured by the Sensation of sound, that is for the loudness their vis 'mva, that is, by the sqiiarc of thc of sound which will hold all pitches. L. ee greatest velocity attained by the oscillating the addition to a footnote on p. lod, re ernng particles. But the' ear has different degrees of especially to this passage.—Translator.] sensibility for tones of different pitch, so that