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HYDROACOUSTICS
ANNUAL JOURNAL |
START | NEW VOL 20 | SEARCH | STATISTICS | PAS - GDANSK DIVISION |
pp. 57-62, vol. 17, 2014 Ignacy Gloza Polish Naval Academy, Gdynia, Poland Krystian Buszman Polish Naval Academy, Gdynia, Poland Key words: sailing vessel; ship identification Abstract: The subject matter of this research is underwater noise generated by sailing vessels in
shallow seas. The classical method for measurement of underwater noise involves measuring
effective acoustic pressure and fits for purposes in the free far field of the source. Despite its
popularity, the method does have some significant limitations. Investigations of underwater
noise generated by moving vessels in shallow seas are almost solely confined to the near field.
In addition, this has a high level of interference and numerous wave reflections. This is why,
as well as using the acoustic pressure measurement method, a complementary method for
measuring acoustic wave intensity is used increasingly often.
The measurements were taken using an underwater measurement module equipped with
a set of detectors. Submerged at 20m, the object moved along a designated trajectory at a
preset speed (as determined by the parameters of the ship’s machinery). Because all of the
on-board equipment generates ship-specific noise, additional measurements were taken of the
vibrations generated by selected ship’s machines to identify those sources.
If known, the distribution of the acoustic field from vessels helps to identify the
characteristic frequencies generated by the ship’s equipment and machinery.
The paper includes a comparison of acoustic wave intensity and acoustic pressure
measurements taken under the same ambient conditions and over the same period.
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