scholarly journals High-Speed Vessel Noises in West Hong Kong Waters and Their Contributions Relative to Indo-Pacific Humpback Dolphins (Sousa chinensis)

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Paul Q. Sims ◽  
Samuel K. Hung ◽  
Bernd Würsig
Keyword(s):  
Hong Kong ◽  
High Speed ◽  
Ambient Noise ◽  
Sound Pressure ◽  
Behavioral Changes ◽  
Noise Levels ◽  
Acoustic Disturbance ◽  
Sousa Chinensis ◽  
Hong Kong Waters ◽  
Low Traffic

The waters of West Hong Kong are home to a population of Indo-Pacific humpback dolphins (Sousa chinensis) that use a variety of sounds to communicate. This area is also dominated by intense vessel traffic that is believed to be behaviorally and acoustically disruptive to dolphins. While behavioral changes have been documented, acoustic disturbance has yet to be shown. We compared the relative sound contributions of various high-speed vessels to nearby ambient noise and dolphin social sounds. Ambient noise levels were also compared between areas of high and low traffic. We found large differences in sound pressure levels between high traffic and no traffic areas, suggesting that vessels are the main contributors to these discrepancies. Vessel sounds were well within the audible range of dolphins, with sounds from 315–45,000 Hz. Additionally, vessel sounds at distances ≥100 m exceeded those of dolphin sounds at closer distances. Our results reaffirm earlier studies that vessels have large sound contributions to dolphin habitats, and we suspect that they may be inducing masking effects of dolphin sounds at close distances. Further research on dolphin behavior and acoustics in relation to vessels is needed to clarify impacts.

Crassicauda sp. in an Indo-Pacific humpback dolphin (Sousa chinensis)

2020 ◽  
Vol 8 (3) ◽  
pp. e000865
Author(s):  
Nathalie France Mauroo ◽  
Philip S L Beh ◽  
Eileen Harris ◽  
San Y Chan ◽  
David I Gibson
Keyword(s):  
Hong Kong ◽  
Mammary Gland ◽  
South China Sea ◽  
Histological Examination ◽  
South China ◽  
First Record ◽  
Postmortem Examination ◽  
Sousa Chinensis ◽  
New Geographical Record ◽  
Hong Kong Waters

A female Indo-Pacific humpback dolphin (Sousa chinensis) stranded in Hong Kong waters presented on postmortem examination with a single nematode with a diameter of 0.1 cm in the mammary gland, as well as mild multifocal chronic mastitis on histological examination. The parasitic material was recognised as a species of Crassicauda. To our knowledge, this is the first record of a species of Crassicauda occurring in an Indo-Pacific humpback dolphin and also represents a new geographical record for this genus in the South China Sea.

Feeding Habits of Indo-Pacific Humpback Dolphins (Sousa chinensis) Stranded in Hong Kong

2004 ◽  
Vol 30 (1) ◽  
pp. 179-188 ◽  
Author(s):  
Nélio B. Barros ◽  
Thomas A. Jefferson ◽  
E.C.M. Parsons
Keyword(s):  
Hong Kong ◽  
Feeding Habits ◽  
Sousa Chinensis

scholarly journals Measurement of Underwater Acoustic Energy Radiated by Single Raindrops

Sensors ◽  
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.

scholarly journals A New Approach to Assess the Quality of Small High-Speed Centrifugal Fans Using Noise Measurement

1999 ◽  
Vol 5 (2) ◽  
pp. 147-153 ◽  
Author(s):  
Dingjun Cui ◽  
Ian A. Craighead
Keyword(s):  
Signal Processing ◽  
Quality Assessment ◽  
Condition Monitoring ◽  
High Speed ◽  
Noise Levels ◽  
New Approach ◽  
Commercial Market ◽  
Centrifugal Fans ◽  
Special Approach

The requirements for a special approach for the quality assessment of small high-speed centrifugal fans are outlined and a new parameter designating the noise levels from the product in comprehensive form will be discussed and described as a criterion for such quality assessment.By applying techniques of signal processing and condition monitoring, the sources of the vibration and noise in different sections of the product can be identified, then the noise from each source from different components can be determined. Using this criterion, more aspects of the quality of the products can be assessed and suggestions to improve the quality of the products can be made. Finally, the assessment of a number ofvacuum cleaner motor/fan units available in the commercial market will be presented and compared with conventional specifications. It will be shown that the new parameter provides a more useful indication of appliance quality.

scholarly journals Distribution of cadmium, chromium, copper, lead and zinc in marine sediments in Hong Kong waters

2007 ◽  
Vol 52 (1) ◽  
pp. 173-173
Author(s):  
S. C. Choi ◽  
Onyx W. H. Wai ◽  
W. H. Lo ◽  
X. D. Li ◽  
C. W. Tsang
Keyword(s):  
Hong Kong ◽  
Marine Sediments ◽  
Lead And Zinc ◽  
Hong Kong Waters ◽  
Copper Lead

Influence of Wind-produced Noise on Orientation in the Sole (Solea solea)

1994 ◽  
Vol 51 (6) ◽  
pp. 1258-1264 ◽  
Author(s):  
J. P. Lagardère ◽  
M. L. Bégout ◽  
J. Y. Lafaye ◽  
J. P. Villotte
Keyword(s):  
Spatial Distribution ◽  
Ambient Noise ◽  
Sound Intensity ◽  
Weather Conditions ◽  
Fish Populations ◽  
Positioning System ◽  
Noise Levels ◽  
Orientation Behaviour ◽  
Solea Solea ◽  
Swimming Trajectories

Sole (Solea solea), telemetered in an enclosure using an acoustic positioning system, changed their swimming trajectories and orientation behaviour as a function of wind strength and direction. Monitoring of the spatial variation in both wind-generated currents and noise spectra in the enclosure indicates that these behavioural changes correspond to patterns in the spatial distribution of noise and to sound intensity. Thus, our observations indicate that sole perceives and reacts to horizontal variability in ambient noise levels. Such behaviour may be important in determining movements of fish populations at sea during poor weather conditions.

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