The Ear as a Frequency Analyzer

Ohm's acoustical law, as formulated by von Helmholtz, states that the human ear is able to analyze a periodic sound wave into its sinusoidal components. As far as the writer knows, there does not exist any systematic study about the limits of this law. In this paper, the results of some experiments on the number of distinguishable partials of multitone signals with harmonic as well as inharmonic components are communicated. The frequency of the lowest partial was varied between 44 and 2000 cps. The results are in agreement with the critical-band concept, indicating that the partials of a complex sound can be “heard out” only if their frequency separation exceeds the critical bandwidth. This fact supports the supposition that the critical bands correspond with the widths of the stimulating pattern of simple tones on the basilar membrane. The masking pattern of a complex tone of 500 cps, determined over the frequency range between 300 and 4000 cps, points in the same direction. An investigation of the minimum frequency separation required to distinguish the pitches of two-tone stimuli resulted in somewhat smaller values than the critical bandwidth, especially in the low-frequency range.