Jones et al. [J. Acoust. Soc. Am. 146, 2912 (2019)] compared an elevated (1.5 m) acoustical measurement configuration using a standard commercial windscreen with a ground-based configuration with a custom windscreen. That study showed that the ground-based measurement method yielded superior wind noise rejection, presumably due to the larger windscreen and lower wind speeds experienced near the ground. This study examines those findings in greater depth by attempting to decouple the effects of windscreens and microphone elevation using measurements at 1.5 m and near the ground with and without windscreens. Simultaneous wind speed measurements at 1.5 m and near the ground were also made for correlation purposes. For the elevated acoustical measurements, three different commercial windscreens were used to further examine impacts of the larger windscreen in the ground-based setup. Results show that the custom windscreen has a more significant noise-reduction impact than microphone elevation, and that the ground-based setup is again preferable for obtaining broadband outdoor acoustic measurements. [Work supported by a U.S. Army SBIR.]
This paper discusses analyses of a ground-based outdoor microphone system designed to be weather-robust. This system employs an inverted half-inch microphone placed one-quarter inch above a thin plastic convex circular plate and enclosed in a dome windscreen. The current iteration of the “compact outdoor unit for ground-based acoustical recordings,” nicknamed COUGARxt, is an improvement over its predecessor because of its thicker windscreen and its thinner plate made of a harder plastic material. One system characterization is anechoic chamber testing, where a sound source was placed at different elevation and azimuthal angles relative to the COUGARxt system to understand performance differences. Acoustical effects of plate orientation and the thicker windscreen are discussed. Another analysis consists of outdoor measurements in a windy but otherwise quiet environment. The COUGARxt system shows improved wind-noise rejection between 3 and 100 Hz, which could be important for improved detection of infrasound sources, including sonic booms and long-range launch vehicle noise.
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