Kœnig's Experiments in Acoustics ¹

Abstract

II. IN a preceding article it was recounted how Kcenig has applied the principle of the wave-siren to prove by direct experiment the influence which phase has upon the quality of a sound. The view taken by Kœnig that this difference may be completely explained by observing the difference in the form of the resultant waves was also briefly set forth. Two large diagrams were given which illustrated the matter very completely. A set of odd members only was taken from a harmonic series in which the amplitudes decreased in inverse ratio to the order of the harmonic; the series having for the ratios of its frequencies the numbers 1:3:5:7:9, with the respective amplitudes 1:$\frac{1}{3}$:$\frac{1}{5}$:$\frac{1}{7}$:$\frac{1}{9}$. These were compounded together, firstly without any difference of phase, and secondly with a difference of phase of ¼ the wave-length. The resultant in one case showed well-rounded sinuosities, and in the other angular zigzags. In the first case the whole of the components had at their origin zero amplitudes, in the second they all, at the origin, had their individual amplitudes at maximum values. Kœnig found the result, when the curves were actually tried upon his wave-siren, to be that though the constituent tones in the two cases were identical in pitch and amplitude the resultant sound from the zig-zag curve was harsh and strident compared with that produced by the rounded sinuosities; thus clearly proving an influence due to difference of phase only.