A reexamination of the frequency discrimination of random‐amplitude tones, and a test of Henning’s modified energy‐detector model

A surprising result is reported by Henning [G. B. Henning, J. Acoust. Soc. Am. 39, 336–339 (1966)]: For frequencies lower than 4000 Hz, frequency discrimination was not impaired by the introduction of random differences in level between the two tones to be discriminated in a two‐interval forced‐choice (2IFC) task. This result is inconsistent with a model of detection and discrimination proposed by Henning [G. B. Henning, J. Acoust. Soc. Am. 42, 1325–1334 (1967)], one of a class of models in which the observer monitors the output of a single auditory filter, as well as with excitation‐pattern models of frequency discrimination. In the first experiment reported here, however, an impairment of frequency discrimination with random differences in level is found when a within‐subjects experimental design is used. In a second experiment, the role of pitch‐intensity relationships in an experimental situation similar to that of Henning (1966) is explored. Finally, in a third experiment, an independent test of this...