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Title: Vertical and slanted sound propagation in the near-ground atmosphere : amplitude and phase fluctuations
Authors: Kamrath, Matthew J.
Ostashev, Vladimir E.
Wilson, D. Keith
White, Michael J.
Hart, Carl R.
Finn, Anthony
Keywords: Sound--Detection
Boundary layer (Meteorology)
Microphone arrays
Drone aircraft
Publisher: Cold Regions Research and Engineering Laboratory (U.S.)
Construction Engineering Research Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Miscellaneous Paper (Engineer Research and Development Center (U.S.)) ; no. ERDC MP-21-2
Is Version Of: Kamrath, Matthew J., Vladimir E. Ostashev, D. Keith Wilson, Michael J. White, Carl R. Hart, and Anthony Finn. "Vertical and slanted sound propagation in the near-ground atmosphere: Amplitude and phase fluctuations." The Journal of the Acoustical Society of America 149, no. 3 (2021): 2055-2071.
Abstract: Sound propagation along vertical and slanted paths through the near-ground atmosphere impacts detection and localization of low-altitude sound sources, such as small unmanned aerial vehicles, from ground-based microphone arrays. This article experimentally investigates the amplitude and phase fluctuations of acoustic signals propagating along such paths. The experiment involved nine microphones on three horizontal booms mounted at different heights to a 135-m meteorological tower at the National Wind Technology Center (Boulder, CO). A ground-based loudspeaker was placed at the base of the tower for vertical propagation or 56m from the base of the tower for slanted propagation. Phasor scatterplots qualitatively characterize the amplitude and phase fluctuations of the received signals during different meteorological regimes. The measurements are also compared to a theory describing the log-amplitude and phase variances based on the spectrum of shear and buoyancy driven turbulence near the ground. Generally, the theory correctly predicts the measured log-amplitude variances, which are affected primarily by small-scale, isotropic turbulent eddies. However, the theory overpredicts the measured phase variances, which are affected primarily by large-scale, anisotropic, buoyantly driven eddies. Ground blocking of these large eddies likely explains the overprediction.
Description: Miscellaneous Paper
Gov't Doc #: ERDC MP-21-2
Rights: Approved for Public Release; Distribution is Unlimited
Appears in Collections:Miscellaneous Paper

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