Loudness Adaptation: Use of the Double Staircase Method and Heterophonic Balances

Abstract

Twelve normal-hearing listeners were adapted monaurally with a 4-kHz pure tone of 60 dB SPL for 5 min following 3 min of preadapting loudness balances. The control ear was simultaneously stimulated every 3 sec with a 0.25-, 1-, or 4-kHz comparison tone of 1- or 2-sec duration. The listener was instructed to compare the loudness of each comparison signal with that of the adapting signal. Comparison signal intensities were controlled by the listener through two recording attenuators with the comparison signal randomly switched to one or the other attenuator. The magnitude of adaptation was calculated at 20-sec intervals. Average adaptation was found to be significantly different with the three comparison signal frequencies used. The greatest amount of measured adaptation occurred with the 4-kHz comparison signal and the least amount with the 0.25 kHz signal. Comparison signal duty cycles of 13 and 23 yielded no difference in the magnitude of measured adaptation.