Measurements of equal loudness and reaction times

Abstract

Kohfeld et al. [Percept. Psychophys. 29, 535–549 (1981)] suggested that reaction times may not be the same for equally loud stimuli. However, their equal-loudness contours showed unusually large level differences between the 1000-Hz standard and the 500- and 5000-Hz comparisons. To investigate the effect of the loudness-matching procedure used by Kohfeld et al., four listeners made equal-loudness judgments using three different methods: (1) a method of limits with the standard and comparison alternating between ears, similar to Kohfeld et al.'s procedure, (2) a method using three interweaved adaptive procedures with a 2I, 2AFC paradigm and monotic, random-order presentation of standard and comparison, and (3) the method of adjustment with monotic, alternating presentation of standard and comparison. Results from the first method resembled those of Kohfeld et al.: at 20, 40, and 60 phons, the 500- and 5000-Hz comparisons were set about 8 dB above the 1000-Hz standard. Results from the second and third methods agreed with each other, but were different from those obtained with the first method: at all three loudness levels, the comparisons were set only a few dB above the standard. Preliminary measurements indicate that reaction times to equally loud tones, as determined with the second and third methods, were approximately equal. [Work supported by NIH grant RR07143.]