Offshore Marine Ambient Noise Measurement Study Based on Laser Interferometer Hydrophone

Sound pressure is an important parameter of marine background noise monitoring. A laser interferometric hydrophone is designed based on Michelson interferometry. By tracking compensation method, immunity from interference of the hydrophone is improved. Error analysis shows that the vibrating membrane is the main source of the sound pressure error, which can be eliminated to a certain extent by a vibrating membrane materials selection. Offshore data show that hydrophone pressure measurement of high precision, and with a good frequency response. By comparison with the theoretical model to some extent also verified the accuracy of data. In coastal waters, wind noise and ship radiate noise is the main noise source of marine ambient noise. Here, marine ambient noise spectrum of three wind speed were calculated, and with Kundsen curves were compared. Results show that measured data and Kundsen curve fitting is better. In addition, the measurement of vessel radiation noise is mainly concentrated in frequency range of 350~500Hz.

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Vector Ocean Ambient Noise Spectrum Simulation Based on Parabolic Equation Model in Shallow Water

Journal of Computational Acoustics ◽

10.1142/s0218396x17500345 ◽

2017 ◽

Vol 25 (02) ◽

pp. 1750034

Author(s):

Liufang Fu ◽

Peng Li ◽

Xinhua Zhang ◽

Shuqing Ma ◽

Chengzhi Gao

Keyword(s):

Parabolic Equation ◽

South China Sea ◽

Particle Velocity ◽

South China ◽

Ambient Noise ◽

Sound Pressure ◽

Noise Spectrum ◽

China Sea ◽

Simulation Results ◽

Horizontal Particle

Ocean ambient noise spectrum is one of the most important characteristics of ambient noise. An ocean vector ambient noise field model was built up based on parabolic equation in this paper. Then the spectra of sound pressure, horizontal particle velocity and vertical particle velocity were calculated applying the model considering noise sources well distributed on the surface with typical summer sound speed profile in South China Sea. The simulation results showed that spectra of sound pressure, horizontal particle velocity and vertical particle velocity were obviously not varied with depth. Then, the simulated results were compared with the experiment results at the receiving depth of a trail in South China Sea in July 2012. Compared with the experimental results, the simulation results are consistent well with the experimental one of sound pressure and horizontal particle velocity in the trend. But the simulation values at low frequency band below 500[Formula: see text]Hz, are not consistent with the experimental one very well, in the band the simulation results are lower than the experimental by about 3–5[Formula: see text]dB. But the simulation result of vertical particle velocity was not consistent with the experimental one, illustrating that the precision of the model might not be enough in the vertical direction.

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Study on Surface Radiation Noise of a Diesel Engine Based on FEM

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.774-776.17 ◽

2013 ◽

Vol 774-776 ◽

pp. 17-20 ◽

Cited By ~ 1

Author(s):

Ye Miao Zhao ◽

Xiao Hui Cao ◽

Chen Hai Guo ◽

Qing Zhen Ma

Keyword(s):

Diesel Engine ◽

Noise Reduction ◽

Sound Pressure ◽

Combustion Engine ◽

Element Model ◽

Noise Spectrum ◽

Surface Radiation ◽

Vibration Velocity ◽

Finite Element Software ◽

Radiation Noise

To evaluate the noise of a diesel engine and provide the basis for the next step for noise reduction, a boundary element model of the diesel engine has been built and finite element software is used to analyze the noise of the engine. Surface vibration velocity distribution, radiation noise spectrum, sound pressure distribution and total noise level are calculated. The calculation results obtained show that the most representative three points of the peak of SPL (sound pressure level) are 500Hz, 1200Hz and 1950Hz; total SPL is 108.99dB; the main sources of the noise of the diesel engine are oil pan, gear chamber cover and flywheel housing, these three parts should be prior; the noise of the lower part and left and right part (the gear chamber cover side and flywheel housing side) of the engine is greater than the upper part and front and rear part; improving the suspension mechanism of the internal combustion engine, optimizing the oil sump, flywheel housing and gear chamber cover and strengthening the rigidity of the skirt of the engine body can be used as the primary means of noise reduction.

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Stream ambient noise, spectrum and propagation of sounds in the goby Padogobius martensii: Sound pressure and particle velocity

The Journal of the Acoustical Society of America ◽

10.1121/1.2783113 ◽

2007 ◽

Vol 122 (5) ◽

pp. 2881 ◽

Cited By ~ 32

Author(s):

Marco Lugli ◽

Michael L. Fine

Keyword(s):

Particle Velocity ◽

Ambient Noise ◽

Sound Pressure ◽

Noise Spectrum

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AMBIENT NOISE: PROBLEM AND STUDY IN THE FRAMEWORK OF UAV AEROACOUSTICS

Akustika ◽

10.36336/akustika20214116 ◽

2021 ◽

pp. 16-21

Author(s):

Petr Moshkov

Keyword(s):

Unmanned Aerial Vehicle ◽

Background Noise ◽

Ambient Noise ◽

Spectral Characteristics ◽

Wind Noise ◽

Community Noise ◽

Noise Masker ◽

Aerial Vehicle

The role of ambient noise in the problem of community noise of propeller-driven unmanned aerial vehicle is considered. The results of the author's measurements of the spectral characteristics of the background in open terrain, in the mountains, near the sea and the highway are presented. An expression is proposed for calculating the spectrum of background noise in open terrain (wind noise). It is shown that the ambient noise can be an effective noise masker of propeller-driven UAV in the low and medium frequencies.

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Measurement of Underwater Acoustic Energy Radiated by Single Raindrops

Sensors ◽

10.3390/s21082687 ◽

2021 ◽

Vol 21 (8) ◽

pp. 2687

Author(s):

Shu Liu ◽

Qi Li ◽

Dajing Shang ◽

Rui Tang ◽

Qingming Zhang

Keyword(s):

Ambient Noise ◽

Sound Pressure ◽

Tap Water ◽

Acoustic Energy ◽

Underwater Sound ◽

Underwater Noise ◽

Energy Characteristics ◽

Sound Energy ◽

Dipole Radiation ◽

Series Of Experiments

Underwater noise produced by rainfall is an important component of underwater ambient noise. For example, the existence of rainfall noise causes strong disturbances to sonar performance. The underwater noise produced by a single raindrop is the basis of rainfall noise. Therefore, it is necessary to study the associated underwater noise when drops strike the water surface. Previous research focused primarily on the sound pressure and frequency spectrum of underwater noise from single raindrops, but the study on its sound energy is insufficient. The purpose of this paper is to propose a method for predicting the acoustic energy generated by raindrops of any diameter. Here, a formula was derived to calculate the underwater sound energy radiated by single raindrops based on a dipole radiation pattern. A series of experiments were conducted to measure the underwater sound energy in a 15 m × 9 m × 6 m reverberation tank filled with tap water. The analysis of the acoustic energy characteristics and conversion efficiency from kinetic to acoustic energy helped develop the model to predict the average underwater sound energy radiated by single raindrops. Using this model, the total underwater sound energy of all raindrops during a rainfall event can be predicted based on the drop size distribution.

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