Tidal Effect in Small-Scale Sound Propagation Experiment

2012 ◽  
Vol 51 ◽  
pp. 07GG08 ◽  
Author(s):  
Seiji Kamimura ◽  
Hanako Ogasawara ◽  
Kazuyoshi Mori ◽  
Toshiaki Nakamura
Keyword(s):  
Sound Propagation ◽  
Tidal Effect ◽  
Small Scale ◽  
Propagation Experiment

Tidal Effect in Small-Scale Sound Propagation Experiment

2012 ◽  
Vol 51 (7S) ◽  
pp. 07GG08
Author(s):  
Seiji Kamimura ◽  
Hanako Ogasawara ◽  
Kazuyoshi Mori ◽  
Toshiaki Nakamura
Keyword(s):  
Sound Propagation ◽  
Tidal Effect ◽  
Small Scale ◽  
Propagation Experiment

Analysis of Tidal Effect on Reciprocal Sound Propagation in Central Pacific Ocean

2008 ◽  
Vol 47 (5) ◽  
pp. 4349-4353 ◽  
Author(s):  
Hanako Ogasawara ◽  
Toshiaki Nakamura ◽  
Hidetoshi Fujimori ◽  
Hiroyuki Hachiya ◽  
Koichi Mizutani
Keyword(s):  
Pacific Ocean ◽  
Sound Propagation ◽  
Tidal Effect ◽  
Central Pacific ◽  
Central Pacific Ocean

scholarly journals Vertical and slanted sound propagation in the near-ground atmosphere : amplitude and phase fluctuations

2021 ◽  
Author(s):  
Matthew Kamrath ◽  
Vladimir Ostashev ◽  
D. Wilson ◽  
Michael White ◽  
Carl Hart ◽  
...  
Keyword(s):  
Large Scale ◽  
Sound Propagation ◽  
Microphone Arrays ◽  
Small Scale ◽  
Sound Sources ◽  
Phase Fluctuations ◽  
Turbulent Eddies ◽  
Low Altitude ◽  
Detection And Localization ◽  
Large Eddies

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.

Machine-Learning of Long-Range Sound Propagation Through Simulated Atmospheric Turbulence

2021 ◽  
Author(s):  
Carl R. Hart ◽  
D. Keith Wilson ◽  
Chris L. Pettit ◽  
Edward T. Nykaza
Keyword(s):  
Machine Learning ◽  
Long Range ◽  
Sound Propagation ◽  
Transmission Loss ◽  
Absolute Error ◽  
Surrogate Data ◽  
Machine Learning Algorithms ◽  
Single Realization ◽  
Time Requirements ◽  
Propagation Experiment

Conventional numerical methods can capture the inherent variability of long-range outdoor sound propagation. However, computational memory and time requirements are high. In contrast, machine-learning models provide very fast predictions. This comes by learning from experimental observations or surrogate data. Yet, it is unknown what type of surrogate data is most suitable for machine-learning. This study used a Crank-Nicholson parabolic equation (CNPE) for generating the surrogate data. The CNPE input data were sampled by the Latin hypercube technique. Two separate datasets comprised 5000 samples of model input. The first dataset consisted of transmission loss (TL) fields for single realizations of turbulence. The second dataset consisted of average TL fields for 64 realizations of turbulence. Three machine-learning algorithms were applied to each dataset, namely, ensemble decision trees, neural networks, and cluster-weighted models. Observational data come from a long-range (out to 8 km) sound propagation experiment. In comparison to the experimental observations, regression predictions have 5–7 dB in median absolute error. Surrogate data quality depends on an accurate characterization of refractive and scattering conditions. Predictions obtained through a single realization of turbulence agree better with the experimental observations.

scholarly journals Directional acoustic radiation in the strut display of male sage grouse Centrocercus urophasianus

1999 ◽  
Vol 202 (21) ◽  
pp. 2893-2909 ◽  
Author(s):  
M.S. Dantzker ◽  
G.B. Deane ◽  
J.W. Bradbury
Keyword(s):  
Sound Propagation ◽  
Acoustic Radiation ◽  
Microphone Array ◽  
Field Measurements ◽  
Centrocercus Urophasianus ◽  
Small Scale ◽  
Sage Grouse ◽  
Radiation Beam ◽  
Acoustic Localization ◽  
In The Wild

We present evidence that the acoustic component of the strut display of male sage grouse Centrocercus urophasianus is highly directional and that the nature of this directionality is unique among measured vertebrates. Where vertebrate acoustic signals have been found to be directional, they are most intense anteriorly and are bilaterally symmetrical. Our results show that sage grouse acoustic radiation (beam) patterns are often asymmetric about the birds' anterior-posterior axis. The beam pattern of the ‘whistle’ note is actually strikingly bilobate with a deep null directly in front of the displaying bird. While the sage grouse display serves to attract potential mates, male sage grouse rarely face females head on when they call. The results of this study suggest that males may reach females with a high-intensity signal despite their preference for an oblique display posture relative to those females. We characterized these patterns using a novel technique that allowed us to map acoustic radiation patterns of unrestrained animals calling in the wild. Using an eight-microphone array, our technique integrates acoustic localization with synchronous pressure-field measurements while controlling for small-scale environmental variation in sound propagation.

The Potential of Ipê (Handroanthus SPP.) and Maçaranduba (Manilkara SPP.) Woods in the manufacture of bows for string instruments

IAWA Journal ◽  
2010 ◽  
Vol 31 (2) ◽  
pp. 149-160 ◽  
Author(s):  
Eduardo Luiz Longui ◽  
Takashi Yojo ◽  
Daniel Romeu Lombardi ◽  
Edenise Segala Alves
Keyword(s):  
Speed Of Sound ◽  
Elasticity Modulus ◽  
Sound Propagation ◽  
Modulus Of Rupture ◽  
Small Scale ◽  
Length Frequency ◽  
String Instruments ◽  
Acoustic Characteristics ◽  
Vessel Elements ◽  
Caesalpinia Echinata

While the wood Caesalpinia echinata (pernambuco wood) is traditionally used in the manufacture of bows for string instruments, wood of other genera such as Handroanthus (syn. Tabebuia) and Manilkara are also used in bow making, but still on a very small scale. This study aims to evaluate the anatomical, chemical, physical, mechanical, and acoustic characteristics of these two latter woods, establishing their potential for bow making. Length, frequency of vessel elements and rays, and the higher percentage of fibers influence the density, modulus of elasticity, modulus of rupture, and the speed of sound propagation, whereas the content of lignin influence the sticks’ stiffness. It appears that Handroanthus bows can provide quality equivalent to that of pernambuco wood. Despite its appropriate heartwood color and texture, Manilkara provides bows of inferior quality.

scholarly journals The investigation of sediment processes in rivers by means of the Acoustic Doppler Profiler

2014 ◽  
Vol 364 ◽  
pp. 368-373 ◽  
Author(s):  
M. Guerrero
Keyword(s):  
Sound Propagation ◽  
Numerical Models ◽  
Climate Change Impacts ◽  
Sediment Concentration ◽  
Small Scale ◽  
Po River ◽  
Pump Station ◽  
Navigation Channel ◽  
Acoustic Doppler Profiler ◽  
River Cross Section

Abstract. The measurement of sediment processes at the scale of a river cross-section is desirable for the evaluation of many issues related to river hydro-morphodynamics, such as the calibration and validation of numerical models for predicting the climate change impacts on water resources and efforts of maintenance of the navigation channel and other hydraulic works. Suspended- and bed-load have traditionally been measured by cumbersome techniques that are difficult to apply in large rivers. The acoustics for the investigation of small-scale sedimentological processes gained acceptance in the marine community because of its ability to simultaneously profile sediment concentration and size distribution, non-intrusively, and with high temporal and spatial resolution. The application of these methods in true riverine case studies presents additional difficulties, mainly related to water depths and stream currents that limit sound propagation into water and challenge the instruments deployment, especially during floods. This article introduces the motivations for using the ADCP for sediment processes investigation other than for flow discharge measurement, summarizes the developed methods and indicates future desirable improvements. In addition, an application on the Po River in Italy is presented, focusing on the calibration of the existing software by means of ADCP recordings. The calibrated model will assist in planning the dredging activities to maintain the navigation channel and the intake of a pump station for irrigation that is periodically obstructed with a sandbar.

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