Enhancement and Masking of Loudness by Environmental Factors

Abstract

The effect of sound, especially noise, on the behavior of people in various environments has been of long-standing interest to researchers. However, the reverse effect, that is, the influence of environmental features on the perception of sound, appears to have received comparatively little attention. One aspect of this problem is addressed in the present work, namely, the dependence of loudness on visually prominent characteristics of outdoor environments, such as vegetation. Three experiments were conducted to assess the effects of visibility of vegetation in outdoor sites on the loudness of neutral sounds (500 Hz tones) ranging between 50 and 80 dB. It was found that, when the ambient noise level was held approximately constant across sites, loudness increased as the percentage of visible vegetation increased. It is argued that expected noise levels are keyed to the extensiveness of visible vegetation and that discrepancies between actual and expected noise levels in outdoor environments result in enhancements of the loudness of the sounds heard there.