Investigation of the mechanisms of low-frequency wind noise generation outdoors

Abstract

Simultaneous measurement of wind noise and the instantaneous wind speed were performed for bare and screened microphones outdoors. Analysis of these measurements demonstrates that the dominant source of pressure fluctuations at the microphone outdoors is the intrinsic turbulence in the flow. This is in contrast to the results of measurements performed in low-turbulence environments by Hosier and Donavan [Natl. Bur. Stand. Rpt. NBSIR79-1599 (Jan. 1979)] and by Strasberg [J. Acoust. Soc. Am. 83, 544–548 (1988)]. For low-turbulence conditions the fluctuating wake of the screen is the dominant noise source. This finding has important implications for windscreen design for outdoor measurements since the principles described by Hosier and Donavan apply only to low-turbulence conditions.