Beats of Mistuned Consonances

Publisher Website
Google Scholar
Abstract
Two simultaneously sounding simple tones of M and N cps, respectively, with M:N slightly different from m:n (both small integral numbers) may give rise to a beat sensation with mN − nM beats per second. For the case m = 1, these beats are usually explained as resulting from harmonics created in the ear by distortion. Experiments indicated, however, that for m ≠ 1 secondary tones cannot be the main origin of these beats because the beat sensation does not disappear when bands of noise are introduced in the frequency ranges around possible harmonics and combination tones. Other experiments in which, for a constant lower toneM, the sound‐pressure level (SPL) of the higher toneN for most distinct beats was determined showed that this SPL decreases gradually for increasing frequency of N, irrespective of frequency ratio. Moreover, it was found that the beats for 200+601 cps manifest themselves in a weak tone sensation with a pitch shifting periodically in a sawtoothlike manner between about 610 and 730 cps. These experimental results suggest that, also for the case 1:n, the beats are not due to combination tones or aural harmonics but are related to periodic variations in the waveform of the overlapping vibration patterns along the basilar membrane, giving rise to corresponding variations in the time pattern of the nerve impulses.

This publication has 8 references indexed in Scilit: