Just-noticeable differences of frequency for masked tones.

Frequency discrimination was measured as a function of level for tones of 500, 1000, 2000, 3000, and 4000 Hz. The tones were masked by a wide-band noise whose level was set to maintain constant E/No. Frequency discrimination was found to improve with level for tones of 500 and 1000 Hz while it grew worse for tones of 3000 and 4000 Hz. The data for 500 and 1000 Hz are accounted for by the periodicity-type neural timing model of Green and Luce ["Counting and Timing Mechanisms in Auditory Discrimination and Reaction Time," in Contemporary Developments in Mathematical Psychology, edited by D. H. Krantz, R. C. Atkinson, R. D. Luce, and P. Suppres (Freeman, San Francisco, 1974). Vol. 2]. The data for 3000 and 4000 Hz are explained by the modified energy detection model of Henning [J. Acoust. Soc. Am. 42, 1325-1334 (1967b)].