ASA S12.9-2016/PART 7 Quantities and Procedures for Description and Measurement of Environmental Sound, Part 7: Measurement of Low-frequency Noise and Infrasound Outdoors in the Presence of Wind and Indoors in Occupied Spaces
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Part 7 of the ANSI/ASA S12.9 series describes cautions and unique techniques for measuring lowfrequency noise (LFN) outdoors in the presence of wind. It is necessary to measure in wind for wind turbine projects and for countless other industrial power and facilities where environmental wind speed cannot be controlled or levels are specified under downwind conditions. The standard also describes a uniform and repeatable methodology for documenting LFN levels and spectra indoors in occupied spaces where modal considerations are important. The principal concern outdoors is wind-induced noise (WIN) created by wind sources alone. The best estimates for WIN versus wind speed are presented herein based on the literature and special testing conducted by the working group for this standard. The standard is intended to define methods for routinely observed or monitored measurements of infrasound and LFN (ILFN) with standard off-the-shelf instrumentation, commercially available or special windscreens, and microphones appropriate to the task at hand. Following the standard methods should promote uniform, repeatable, and comparable data from site to site.