Loudness scaling and masking in rats.

Two groups of Sprague-Dawley-derived rats (N?=?16) were trained on operant discriminations in which the discriminanda were 2 sound pressure levels of a 4-kHz tone. The discriminanda were chosen so that the loudness difference between stimuli was equivalent for each group when calculated from a power function with an exponent of .35. Half of each group learned the discrimination in quiet, and the other half learned it in a background of white noise. Within the quiet and the noise conditions, the asymptotic discriminability of stimuli separated by equal loudness differences was equivalent, and discriminability was lower in noise. This is consistent with both the human literature on masked loudness and a model of psychophysical scaling (R. Pierrel-Sorrentino and T. G. Raslear; see record 1981-20539-001) in which animals judge perceived differences between stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)