Geo-Acoustic Parameters Inversion from Vertical Coherence Characteristic of Ambient Noise

2013 ◽  
Vol 385-386 ◽  
pp. 567-570
Author(s):  
Chun Xia Meng ◽  
Gui Juan Li ◽  
Liang Zhang
Keyword(s):  
Shallow Water ◽  
Acoustic Field ◽  
Relative Stability ◽  
Ambient Noise ◽  
Frequency Range ◽  
Shallow Sea ◽  
Acoustic Parameters ◽  
Different Seasons ◽  
Noise Data ◽  
Parameters Inversion

In shallow sea the wave of ambient noise contains the information of environment acoustic field. In theory, vertical coherence, which is one of the numerous ambient noise field characters, can be used to invert geo-acoustic parameters because of its relative stability. The ambient noise data were collected in two different seasons using two vertical-laid hydrophones in shallow water. Then acoustic parameters of semi-infinite space seabed are inversed from the vertical coherence of measured ambient noise in the frequency range of 100Hz~3 kHz. The predicted vertical coherence curve of ambient noise, which is computed using inversed parameters, agrees with the measured curve by comparison. The experiment results show that geo-acoustic parameters can be inversed effectively by the vertical coherence of ambient noise.

Using Ambient Noise to Inverse Geo-Acoustic Parameters

2012 ◽  
Vol 588-589 ◽  
pp. 851-855
Author(s):  
Chun Xia Meng ◽  
Gui Juan Li ◽  
Liang Zhang
Keyword(s):  
Shallow Water ◽  
Ambient Noise ◽  
Theoretical Study ◽  
Ocean Surface ◽  
Ray Theory ◽  
Acoustic Parameters ◽  
Low Frequencies ◽  
Research Results ◽  
Noise Data ◽  
Stratified Ocean

This paper presents a theoretical study of the vertical coherence of ocean ambient noise as the source is the windy ocean surface on the ray theory. At low frequencies less than 2 kHz, the sensitivity of stratified fluid seabed to the vertical coherence of ambient noise in shallow water is analyzed under the condition of distance-irrespective stratified ocean. Using ambient noise data from Chinese north shallow water seabed geo-acoustics parameters are obtained, and the research results show that the inverted method is effective.

Short range sound propagation in shallow water and geo-acoustic parameters inversion

2012 ◽  
Vol 131 (4) ◽  
pp. 3280-3280
Author(s):  
Xuegang Zhang ◽  
Chunxia Meng ◽  
Haohao Hu ◽  
Jing Han
Keyword(s):  
Shallow Water ◽  
Short Range ◽  
Sound Propagation ◽  
Acoustic Parameters ◽  
Parameters Inversion

SIMULATION OF UNDERWATER ACOUSTICAL FIELD FLUCTUATIONS IN SHALLOW SEA WITH RANDOM INHOMOGENEITIES OF SOUND SPEED: DEPTH-DEPENDENT ENVIRONMENT

2014 ◽  
Vol 22 (01) ◽  
pp. 1440002 ◽  
Author(s):  
OLEG E. GULIN ◽  
IGOR O. YAROSHCHUK
Keyword(s):  
Shallow Water ◽  
Sound Speed ◽  
Scientific Literature ◽  
Water Layer ◽  
Statistical Simulation ◽  
Frequency Range ◽  
Shallow Sea ◽  
Field Fluctuations ◽  
Pekeris Waveguide ◽  
Speed Fluctuations

Statistical problems encountered in the study of the influence of random inhomogeneities in layered shallow water on the propagation of sound signal is considered. The study is carried out by the example of two-layer models of the sea — a stochastic Pekeris waveguide and a waveguide with a regular refraction in the water layer, which describes the presence of the thermocline. The results were obtained by statistical simulation without approximations and assumptions. In the middle frequency range for actual parameters of sound speed fluctuations in shallow sea with a loss penetrable bottom, the specific features of acoustic field statistical moments behavior have been discovered. They did not get adequate attention in the scientific literature.

Extracting modal structure from vertical array ambient noise data in shallow water

1995 ◽  
Vol 98 (5) ◽  
pp. 2971-2971 ◽  
Author(s):  
Paul Hursky ◽  
William A. Kuperman ◽  
William S. Hodgkiss
Keyword(s):  
Shallow Water ◽  
Ambient Noise ◽  
Vertical Array ◽  
Modal Structure ◽  
Noise Data

Effect of Guide’s Acoustic Parameters on Vertical Directivity of the Marine Ambient Noise

2014 ◽  
Vol 577 ◽  
pp. 1207-1210
Author(s):  
Chun Xia Meng ◽  
Hao Mu ◽  
Gui Juan Li
Keyword(s):  
Shallow Water ◽  
Sound Speed ◽  
Ambient Noise ◽  
Sound Propagation ◽  
Sea Water ◽  
Surface Boundary ◽  
Ray Theory ◽  
Directivity Characteristic ◽  
Acoustic Parameters ◽  
Equipment Performance

The vertical directivity characteristic of ambient noise is one inherent characteristic of the ocean in shallow water. And it includes the information of guide’s acoustic characteristic information. The marine guide is composed of sea water; seabed and surface boundary, there into, the acoustic parameters of seabed are hardly obtained exactly. In this paper, the model of vertical directivity for ambient noise is established. Based on the ray theory of sound propagation, the influence of guide’s acoustic parameters which include sound speed, density and attenuation coefficient on vertical directivity of marine ambient noise is simulated. The results are propitious to analysis and command the characteristics of ambient noise, and valuable to accelerate the exertion of acoustic equipment performance.

scholarly journals Theoretical Model of Acoustic Wave Propagation in Shallow Water

2017 ◽  
Vol 24 (2) ◽  
pp. 48-55 ◽  
Author(s):  
Eugeniusz Kozaczka ◽  
Grażyna Grelowska
Keyword(s):  
Shallow Water ◽  
Acoustic Field ◽  
Acoustic Waves ◽  
Sound Propagation ◽  
Low Frequency ◽  
Water Layer ◽  
Surface Shape ◽  
Shallow Sea ◽  
Multiple Reflections ◽  
Indirect Determination

Abstract The work is devoted to the propagation of low frequency waves in a shallow sea. As a source of acoustic waves, underwater disturbances generated by ships were adopted. A specific feature of the propagation of acoustic waves in shallow water is the proximity of boundaries of the limiting media characterised by different impedance properties, which affects the acoustic field coming from a source situated in the water layer “deformed” by different phenomena. The acoustic field distribution in the real shallow sea is affected not only by multiple reflections, but also by stochastic changes in the free surface shape, and statistical changes in the seabed shape and impedance. The paper discusses fundamental problems of modal sound propagation in the water layer over different types of bottom sediments. The basic task in this case was to determine the acoustic pressure level as a function of distance and depth. The results of the conducted investigation can be useful in indirect determination of the type of bottom.

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