Combination Tones and Other Related Auditory Phenomena

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1908. Excerpt: ... SECTION 3. Later Experiments On Interruption Tones. We saw that the earlier studies of the periodically variable tones were made by physicists, and that they had come to a rather general conclusion that if a tone n is interrupted periodically m times in a certain period of time, other tones, corresponding to n--m and n--m should arise as actual pendular vibrations in the air; and that in some cases these tones had actually been located as to their pitch by the aid of resonators, though the question of objectivity had not been explicitly considered. Several investigators had also noticed a tone corresponding to m, though the results of the mathematical determinations did not show such a vibration. The tone m, moreover, had apparently never been resonated objectively. In 1887 H. Dennert1 took up the problem where Koenig had left it. Dennert's own description of method and results follows: ' On a disk with three circles which were each divided into 96 equal parts, ' he so constructed holes of equal diameter 'that on the first circle 4 parts that were perforated regularly alternated with 4 unperforated ones; on the second circle 3 perforated parts, with 3 unperforated ones; on the third 2 perforated, with 2 unperforated parts. Therefore on the first circle were twelve groups of 4 holes with 4 blank spaces between each group, in the second 16 groups of 3 holes with 3 blank spaces between each group, and on the third 24 groups of 2 holes with 2 blank spaces between each group. Now if the circles were blown upon through a tube during the rotation of the disk, one heard, with slow rotation, beats which, with more rapid rotation, merged into tones. The beats of the third circle first went into a tone, then those of the second, and lastly those of the first. In ever...