Visual influence of outdoor vegetation on loudness

Abstract

Loudness of sounds heard outdoors may be influenced by visual features of the listener's environment. Aylor and Marks [J. Acoust. Soc. Am. 59, 397–400 (1976)] found that estimated loudness magnitudes of noise diminished at visibility of sound sources in an outdoor environment improved. The present study sought to determine whether the visibility of vegetation and man‐made structures would exert any influence on estimated loudness magnitudes of tones presented to listeners through headphones under outdoor conditions. Data were collected within five sites that differed systematically in visible vegetation (trees, shrubs, etc.) ranging from a site with no visible man‐made structures (woods) to a site with no visible vegetation (city street). Equal numbers of male and female listeners generated loudness functions for each site. Trend analysis indicated that the obtained functions differed significantly across sites both in overall means (p < 0.01) and slopes (p < 0.01). None of the functions departed significantly from linearity in log‐log coordinates, i.e., power functions. Loudness magnitudes were largest in the completely wooded site and diminished as the proportion of visible vegetation in sites decreased. [Work supported by USDA USFS.]