Long-term, global-scale statistics of sound propagation

Abstract

The near-surface sound levels emitted due to a point source show a large variability caused by sound propagation through changing meteorological conditions. To assess this variability, this study uses a numerical model of sound propagation which accounts for ground reflection, atmospheric refraction, and turbulence effects. The atmospheric inputs to the model-including turbulence-are calculated from Numerical Weather Prediction data. The method is used to investigate the relative sound levels at a range of 1.5 km from a 40 Hz sound source. The outstanding diversity of sound propagation conditions is illustrated over the globe. Over the long term, the sound propagation climates at selected sites are found to be modulated by the dominant wind regimes, the seasonal and diurnal cycles. The explored sensitivities stress the need for a careful assessment of sound scattering by turbulence and absorption by the surface.

Sensitivity of shot detection and localization to environmental propagation

“…Atmospheric parameters can be obtained from Numerical Weather Systems (e.g. [10]. Ground parameters may be known from Geographic Information Systems.…”

Spatial-temporal coherence of acoustic signals propagating in a refractive, turbulent atmosphere

“…Equations (6), (8), (10), and (12) are the starting equations of our analysis. These equations, except for Eq.…”

“…[7][8][9] Closed-form equations for the statistical moments of arbitrary order of the sound-pressure field propagating above an impedance ground in a refractive, turbulent atmosphere were derived 10 and applied to the analysis of sound scattering into refractive shadow zones 11 and assessment of "acoustic climates." 12 The previously cited works primarily deal with monochromatic sound waves propagating through a turbulent atmosphere with spatial fluctuations in temperature and wind velocity. Experimental and theoretical studies of the frequency spectra of log-amplitude and phase fluctuations published prior to the 1980s are overviewed in Refs.…”