Duration of increment, magnitude estimation adaptation and a proposed loudness function

In a previous experiment on the effects of loudness adaptation on magnitude estimation (M.E.), monaural loudness adaptation was demonstrated above 30 db SL (Weiler et al, Brit. J. Audiol., 1981, 15, 210-204). Adaptation was measured by a modified method of M.E. above the loudness limit proposed by Fishkin et al (J. Ac. Soc. Am., 1977, S61). The adapting signal, a continuous pure tone, did not produce statistically significant differences in loudness M.E. for the majority of listeners. The study of Weiler et al had results similar to those of Fishkin et el, but raised questions about the comparison signal increment, since when a 20-db comparison signal was superimposed, for 5 sec out of every 30, to an ongoing signal of 60 db SPL, the subsequent judgments demonstrated an immediate and cumulative adaptation effect. The present study investigated duration effects of the comparison signal on loudness adaptation through M.E. procedures. Normal-hearing Ss (N: 10, mdn age: 24 yrs) served. The first of 3 conditions (5-sec duration of a 20-db comparison signal) showed a sizable change in M.E. for loudness, and was significantly different from conditions using 1- or 0.5-sec durations, demonstrating that a reduction in the duration of the comparison signal significantly lessened the loudness adaptation effect of the adapting signal. A discussion of the results in comparison to other studies was provided.