Modulation of loudness by environmental visual information

Abstract

Loudness of sounds heard in outdoor settings is reportedly subject to visual influences, viz., the visibility of sound sources [D. E. Aylor and L. E. Marks, J. Acoust. Soc. Am. 59, 397–400 (1976)] and the visibility of vegetation [B. E. Mulligan et al., J. Acoust. Soc. Am. Suppl. 1 67, S22 (1980)]. The latter finding, however, was considered to be questionable due to the possibility of differential masking by ambient noise in the outdoor sites investigated. To assess this possibility, a second experiment was conducted at the original five sites with equalized ambient noise levels. As in the first experiment, observers estimated loudness magnitudes of 500 Hz tones presented through headphones. Evidence of masking was apparent at all sites, but loudness again was found to increase as a function of the proportion of visual vegetation. This finding does not appear to be attributable to differential masking. A third experiment conducted in the laboratory relied upon photographic projections of the same sites a...