On the relations among temporal integration for loudness, loudness discrimination, and the form of the loudness function. (A)

Temporal integration for loudness was measured as a function of level from 2 to 60 dB SL using 2-, 10-, 50-, and 250-ms tones at 5 kHz. The adaptive 2I,2AFC procedure converged at the level required to make the variable stimulus just louder than the fixed stimulus. Thus the data yield estimates of the levels required to make tones of different durations equally loud and of the just noticeable differences for loudness level.

Results for four listeners with normal hearing show that the amount of temporal integration, defined as the level difference between equally loud short and long tones, varies markedly with level and is largest at moderate levels. The effect of level increases as the duration of the short stimulus decreases and is largest for comparisons between the 2- and 250-ms tones.

The loudness-level jnds are also largest at moderate levels and, contrary to traditional jnds for the level of two equal-duration tones, they do not appear to depend on duration. The level dependence of temporal integration and the loudness jnds are consistent with a loudness function [log(loudness) versus SPL] that is flatter at moderate levels than at low and high levels. [Work supported by NIH-NIDCD R01DC02241 and the Technical University of Denmark.]