The effect of temporal patterns of sound energy on the loudness of intensity increment sounds.

Abstract

This paper is on the perception of transient sounds whose sound energy has a global inbalance on the temporal dimension. From previous studies, the loudness of such sounds can be approximated by their mean energy level. Systematic deviations from this approximation were examined here. Intensity increment sounds consisting of two sound-pressure levels were used in all the experiments. In the first experiment, the stimulus sounds were of an equal duration (800 ms) and a nearly equal mean energy level (73.4 dBA). The loudness of these sounds was measured by magnitude estimation without assigned modulus. As a result, the sounds were louder when the level of the onset portion was higher or when the level difference within the sounds was smaller. No positive effects of the maximum level appeared. In the second experiment, the total duration of the stimulus sounds was varied from 400 ms to 1600 ms, and sounds including considerably long increments were also used. The conclusion of the first experiment was supported except when the increment duration or the whole duration was long. Finally, the loudness differences within increment sounds were estimated. Subjective ‘loudness differences’ were judged directly by the subjects and decided mostly by the level difference within the sounds. In conclusion, effects caused by the following physical variables were found: (1) onset level and (2) level difference within the sounds.