A procedure for making rapid audiometric assessments of animal subjects, based on the ability of weak stimuli to modify the strength of reflexes elicited by subsequently presented strong stimuli, is described. Pure-tone detection thresholds for rats and guinea pigs determined by this procedure are quite comparable to those determined by operant techniques, and are similarly sensitive to ototoxic insult. The procedure is also applicable to the assessment of suprathreshold sensory function, and offers advantages over commonly used procedures for assessing ototoxicity.