scholarly journals Calculation and auralization of the sound propagation characteristics based on the A-method in the ASJ Prediction Model 1998: Applications to the excess attenuation by ground surface and to the sound diffraction by barrier

2003 ◽  
Vol 24 (6) ◽  
pp. 394-397
Author(s):  
Teruo Iwase ◽  
Kazutoshi Fujimoto ◽  
Hiroto Yasuoka ◽  
Tetsuya Sakuma
Keyword(s):  
Prediction Model ◽  
Sound Propagation ◽  
Ground Surface ◽  
Propagation Characteristics ◽  
Sound Diffraction ◽  
Excess Attenuation

A study on variations in excess attenuation due to ground surface and meteorological conditions based on a long-term outdoor sound propagation experiment

2021 ◽  
Vol 263 (2) ◽  
pp. 4368-4375
Author(s):  
Takatoshi Yokota ◽  
Koichi Makino ◽  
Genki Iizumi ◽  
Takuya Tsutsumi
Keyword(s):  
Sound Propagation ◽  
Meteorological Data ◽  
Surface Condition ◽  
Ground Surface ◽  
Prediction Method ◽  
Meteorological Condition ◽  
Pulse Method ◽  
Meteorological Conditions ◽  
Ground Condition ◽  
Excess Attenuation

From the winter of 2018, outdoor sound propagation experiments (maximum horizontal range: 300 m) have been repeatedly conducted three times a day on weekdays at a glider airfield in Hokkaido, Japan. The ground condition of the experimental field is grass-covered in summer and snow-covered in winter. In each experiment, impulse responses have been measured by time-stretched pulse method and excess attenuation has been obtained at receiving points. Meteorological data at the field has been also measured. Based on the data of excess attenuation collected under various meteorological conditions over a long period, variation in sound propagation characteristics due to the differences in ground surface condition and meteorological condition has been investigated. The numerical analysis based on the GFPE method has been also carried out with changing the parameter of meteorological condition and ground surface condition. By comparing the results with the experimental data, the prediction method of the variations in excess attenuation has been also investigated.

A comparison of the ground excess attenuation model in Harmonoise with finite-difference time-domain solutions under grounds with mixed types

2021 ◽  
Vol 263 (1) ◽  
pp. 5584-5594
Author(s):  
Yusaku Koshiba ◽  
Takuya Oshima
Keyword(s):  
Finite Difference ◽  
Numerical Method ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Sound Propagation ◽  
Ground Surface ◽  
Flow Resistivity ◽  
Mixed Types ◽  
Difference Time ◽  
Excess Attenuation

Total noise exposure is calculated for the evaluation of health effects caused by environmental noise. For the calculation, computationally drawn noise maps are used. In the computation process, sound propagation over ground surface with mixed types should be calculated for better accuracy. One engineering model that allows such calculation is the ground excess attenuation model of the Harmonoise model. However, the applicability of the model to such complex grounds remains unclear. In this study, a 40m-length ground surface with a discontinuity in flow resistivity is defined. By moving the discontinuity position, sound propagation from a point source and a receiver at each end is calculated using the model and a numerical method. The numerical method is the finite-difference time-domain method with porous medium modeling that has been proven to be accurate. It is found from the numerical results that in higher frequencies the excess attenuations in terms of the discontinuity position have fluctuations. The fluctuations are found to correspond to the interference by diffraction path difference passing the discontinuity. In contrast, the model results exhibit smooth transition from an extremity of single flow resistivity surface to another. A simple model of such diffraction needs to be developed.

scholarly journals Sound diffraction on an elastic spheroidal shell

2021 ◽  
Vol 3 (397) ◽  
pp. 97-114
Author(s):  
A. Kleschev ◽  
Keyword(s):  
Group Velocity ◽  
Planar Waveguide ◽  
Sound Propagation ◽  
Spectral Characteristics ◽  
Sound Field ◽  
Signal Propagation ◽  
Elastic Bottom ◽  
Harmonic Signals ◽  
Scattered Fields ◽  
Sound Diffraction

Object and purpose of research. This paper obtains solutions and performs estimations of characteristics of sound reflection and scattering by ideal and elastic bodies of various shapes (analytical and non-analytical) near media interface, or underwater sonic channel, or in a planar waveguide with a solid elastic bottom. Materials and methods. The harmonic signals are investigated with the method of normal waves based on the phase velocity of signal propagation, and impulse signals related to the energy transfer are studied using the method of real and imaginary sources and scatterers based on the group velocity of propagation. Main results. The scattered sound field is calculated for ideal spheroids (elongated and compressed) at fluid – ideal medium interface. The spectrum of a scattered impulse signal is calculated for a body placed in a sonic channel. First reflected impulses are found for an ideal spheroid in a planar waveguide with anisotropic bottom. Conclusion. In the studies of diffraction characteristics of bodies at media interfaces it was found that the main contribution to scattered field is given by interference of scattered fields rather than interaction of scatterers (real or imaginary). It is shown that at long distances the spectral characteristics of the channel itself have a prevalent role. When impulse sound signals in the planar waveguide are used, it is necessary to apply the method of real and imaginary sources and scatterers based on the group velocity of sound propagation.

scholarly journals Infrasound propagation in the Arctic

2021 ◽  
Author(s):  
D. Wilson ◽  
Vladimir Ostashev ◽  
Michael Shaw ◽  
Michael Muhlestein ◽  
John Weatherly ◽  
...  
Keyword(s):  
Sound Propagation ◽  
Ground Surface ◽  
Polar Vortex ◽  
Basic Research ◽  
Arctic Region ◽  
Initial Step ◽  
The Arctic ◽  
Equation Modeling ◽  
Katabatic Wind ◽  
Long Distance

This report summarizes results of the basic research project “Infrasound Propagation in the Arctic.” The scientific objective of this project was to provide a baseline understanding of the characteristic horizontal propagation distances, frequency dependencies, and conditions leading to enhanced propagation of infrasound in the Arctic region. The approach emphasized theory and numerical modeling as an initial step toward improving understanding of the basic phenomenology, and thus lay the foundation for productive experiments in the future. The modeling approach combined mesoscale numerical weather forecasts from the Polar Weather Research and Forecasting model with advanced acoustic propagation calculations. The project produced significant advances with regard to parabolic equation modeling of sound propagation in a windy atmosphere. For the polar low, interesting interactions with the stratosphere were found, which could possibly be used to provide early warning of strong stratospheric warming events (i.e., the polar vortex). The katabatic wind resulted in a very strong low-level duct, which, when combined with a highly reflective icy ground surface, leads to efficient long-distance propagation. This information is useful in devising strategies for positioning sensors to monitor environmental phenomena and human activities.

Sign in / Sign up

Export Citation Format

Share Document