Wind-induced pseudo-noise and leaf-rustle noise

Abstract

The purpose of this study is to describe, as quantitatively as possible, wind-induced noise in typical environments, where winds are not extreme and wind-sensitive noise sources such as trees are present. Ambient sound-level data measured in support of the Air Tour Management Plans (ATMP) of the National Park Service in conjunction with the Volpe Transportation Systems Center are used to form the baseline for wind-induced noise in situations where there is little, if any, leaf noise. Data that were collected in two relatively quiet areas serve to demonstrate the increase in wind-induced noise that results from leaf rustle. The data listed in Appendix A are our best estimate for wind-induced pseudo-noise as a function both of frequency in one-third octave bands and of wind speed for polyester, low-porosity 20 to 30 cm diameter windscreens. As such, the Appendix A data can be used to roughly eliminate wind-induced pseudo-noise from measurements made in residential or other non-wilderness situations. As a practical matter, at least at low to moderate wind speeds (2 to 5 m/s), such corrections for wind-induced pseudo-noise are unneeded, because these pseudo-noise levels are well below even a quiet ambient of leaf-rustle sound.