Low-frequency sound absorption in air

Zuckerwar, Allan J.; Meredith, Roger W.

doi:10.1121/1.2021392

Cited by 5 publications

(4 citation statements)

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“…Previous studies have reported weather conditions, ambient noise, and other factors can influence the attenuation and detection of bird songs (Harris , Morton , Zuckerwar and Meredith , Larom et al , Catchpole and Slater ). Our results affirm weather conditions (i.e., temperature, wind speed and direction, relative humidity) are important factors.…”

Section: Discussionmentioning

confidence: 99%

Modeling audible detection of prairie grouse booming informs survey design

Holt

Butler

2018

J Wildl Manag

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Many wildlife surveys, especially surveys of birds, are reliant upon audible detection of individuals. Many factors can affect call frequency and sound attenuation, which influence audible detection. Prairie grouse surveys are conducted during lekking and courtship (i.e., booming) to take advantage of frequent vocalization, resulting in greater detectability. Some researchers assume booming can be detected >1.6 km away. To test this assumption and determine factors affecting attenuation and detectability of booming, we established artificial lesser prairie‐chicken (Tympanuchus pallidicinctus) leks. We conducted sound detection trials at these leks using playback of recordings of male lesser prairie‐chickens calibrated to appropriate sound intensity. We modeled detectability using generalized linear mixed‐effects models with distance from lek and weather conditions as covariates. Our model suggested the odds of detecting lesser prairie‐chicken booming decreased 96.8% with each 1‐km increase in distance. Detectability decreased with increased wind speed and temperature, increased with relative humidity, and was influenced by wind direction. We use this model to predict probability of missing leks for line‐transects or point counts. For example, a survey of 1.6‐km‐wide transects during average weather (17.0°C and 60% relative humidity) with 12 km/hour winds would have a 25.6% (95% CI = 3.0–77.2%) to 77.6% (95% CI = 27.3–97.6%) chance, depending on wind direction, of detecting booming lesser prairie‐chickens within the surveyed strip. If point counts with a 0.8‐km radius were conducted under the same conditions, detectability would range from 17.7% (95% CI = 1.7–70.3%) to 70.3% (95% CI = 18.5–96.7%) depending on wind direction. To improve the overall chances of detecting lesser prairie‐chicken booming to ≥80%, surveys would have to be repeated 3 to 4 times. Our model describes the audibility of lesser prairie‐chicken booming and can be used to optimize tradeoffs among survey logistics (e.g., number of surveys needed, point spacing, wind speed thresholds) and detectability. © 2018 The Authors. Journal of Wildlife Management Published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.

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Section: Discussionmentioning

confidence: 99%

Modeling audible detection of prairie grouse booming informs survey design

Holt

Butler

2018

J Wildl Manag

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“…The conversion of attenuation coefficients to other units such as dB/m and Np/m is described in a monograph by Knudsen, 29 though their notation is not consistent in the literature. 30 Typical values in air 31 and sea water 32 in standard conditions at low frequencies are given in Table 2. It can be seen that the attenuation induced by numerical damping in the BEM is of the same order of magnitude as attenuation in air in the considered frequency range.…”

Section: Quantification Of Numercial Damping In the Acoustic Bem For mentioning

confidence: 99%

Quantification of Numerical Damping in the Acoustic Boundary Element Method for Two-Dimensional Duct Problems

Baydoun

Marburg

2018

J. Theor. Comp. Acout.

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Spurious numerical damping in the collocation boundary element method is considered for plane sound waves in two-dimensional ducts subjected to rigid and absorbing boundary conditions. Its extent is quantified in both conditions based on a damping model with exponential decay, and meshes of linear and quadratic continuous elements are studied. An exponential increase of numerical damping with respect to frequency is found and the results suggest an upper bound for given element-to-wavelength ratios. The quantification of numerical damping is required for evaluation of meshes covering a large number of waves, and real damping phenomena can be prevented from overestimation.

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“…The viscous and thermal effects on fluid motion in a pipe of radius r result in an absorption coefficient of (Kinsler, 1982) where η and η e are the true and effective coefficients of shear viscosity, γ is the ratio of specific heats, κ is the thermal conductivity of the fluid, and C p is the specific heat at constant pressure. The absorption coefficient has been studied extensively resulting in models that consider the effects of humidity, temperature, pressure, and other complicating assumptions; see for example Rodarte, et al (2000), Zuckerwar and Meredith (1985), Page and Mee (1984), and Tijdeman (1975). The additional complications were not deemed necessary, as the damping in the cavity will be adjusted at a later date once experimental data is available.…”

Section: Fluid Dampingmentioning

confidence: 99%

Optimization of a piezoelectric acoustical compressor

Dickens¹,

Baz

2005

SPIE Proceedings

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A one-dimensional, axisymmetric, linear finite element model describing a fluid interacting with a piezoelectric actuator is developed. This system is used to generate finite amplitude standing waves in an acoustic cavity with rigid walls. The model includes the effects of viscous and thermal damping of the fluid at the boundary of the cavity, and material damping in the piezoelectric actuator. Two types of piezoelectric actuators are considered, a stacked layer actuator, and a bending bimorph actuator. The resulting finite element equations are used to determine the optimum shape for the acoustic cavity that results in the highest pressure for the least input power. Optimal chambers were found that could generate ± 19 psi at 1700 Hz for 50 watts of power using air as a working fluid and ± 70 psi at 950 Hz for 42 watts of power using R-134A as a working fluid. The optimization results were verified against the commercial finite element code ANSYS and published experimental data.

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Low-frequency sound absorption in air

Cited by 5 publications

References 0 publications

Modeling audible detection of prairie grouse booming informs survey design

Modeling audible detection of prairie grouse booming informs survey design

Quantification of Numerical Damping in the Acoustic Boundary Element Method for Two-Dimensional Duct Problems

Optimization of a piezoelectric acoustical compressor

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