Source level measurements of 1.8 lb and 1.1 oz underwater sound signals

J. M. Thorleifson; P. D. Boyle

doi:10.1121/1.2003498

A Reference Spectrum Model for Estimating Source Levels of Marine Shipping Based on Automated Identification System Data

Journal of Marine Science and Engineering ◽

10.3390/jmse9040369 ◽

2021 ◽

Vol 9 (4) ◽

pp. 369 ◽

Cited By ~ 1

Author(s):

Alexander MacGillivray ◽

Christ de Jong

Keyword(s):

Objective Assessment ◽

Noise Pollution ◽

Specific Reference ◽

Identification System ◽

Reference Spectrum ◽

Underwater Sound ◽

The North ◽

Joint Monitoring ◽

Source Level ◽

Spectrum Model

Underwater sound mapping is increasingly being used as a tool for monitoring and managing noise pollution from shipping in the marine environment. Sound maps typically rely on tracking data from the Automated Information System (AIS), but information available from AIS is limited and not easily related to vessel noise emissions. Thus, robust sound mapping tools not only require accurate models for estimating source levels for large numbers of marine vessels, but also an objective assessment of their uncertainties. As part of the Joint Monitoring Programme for Ambient Noise in the North Sea (JOMOPANS) project, a widely used reference spectrum model (RANDI 3.1) was validated against statistics of monopole ship source level measurements from the Vancouver Fraser Port Authority-led Enhancing Cetacean Habitat and Observation (ECHO) Program. These validation comparisons resulted in a new reference spectrum model (the JOMOPANS-ECHO source level model) that retains the power-law dependence on speed and length but incorporates class-specific reference speeds and new spectrum coefficients. The new reference spectrum model calculates the ship source level spectrum, in decidecade bands, as a function of frequency, speed, length, and AIS ship type. The statistical uncertainty (standard deviation of the deviation between model and measurement) in the predicted source level spectra of the new model is estimated to be 6 dB.

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Standards for measurement and reporting of underwater sound: Application to the source level of trailing suction hopper dredgers.

The Journal of the Acoustical Society of America ◽

10.1121/1.3588097 ◽

2011 ◽

Vol 129 (4) ◽

pp. 2461-2461

Author(s):

Christ A. F. de Jong ◽

Michael A. Ainslie ◽

Erwin W. Jansen ◽

Benoit A. J. Quesson

Keyword(s):

Underwater Sound ◽

Source Level

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Relationship of swim-bladder shape to the directionality pattern of underwater sound in the oyster toadfish

Canadian Journal of Zoology ◽

10.1139/z97-160 ◽

1998 ◽

Vol 76 (1) ◽

pp. 134-143 ◽

Cited By ~ 52

Author(s):

John F Barimo ◽

Michael L Fine

Keyword(s):

Sound Source ◽

Sound Pressure ◽

Sound Production ◽

Swim Bladder ◽

Underwater Sound ◽

York River ◽

Coefficients Of Variation ◽

Source Level ◽

Oyster Toadfish ◽

Relationship Of

The swim bladder of the oyster toadfish, Opsanus tau, has a distinctive heart shape with two anterior protrusions separated by a midline cleft. The lateral surfaces contain intrinsic muscles that meet at the caudal midline, but the rostromedial surface is muscle-free. We hypothesize that swim-bladder design represents a compromise between opposing tendencies toward (i) an omnidirectional sound source that would optimize a male's opportunity to attract females from any direction, and (ii) a directional sound source that would shield the nearby ears during sound production. To determine if the directionality of toadfish sound is consistent with this hypothesis, boatwhistle advertisement calls of individually identified males were recorded in the York River, Virginia, by means of two calibrated hydrophones and a waterproof recording system: one hydrophone was fixed 1 m in front of the fish and the second was roving. Boatwhistles in the horizontal plane propagated in a modified omnidirectional pattern that was bilaterally symmetrical. The mean sound pressure was 126 dB re: 1 µPa at 0°. The sound pressure level decreased by approximately 1 dB at ±45°, after which levels increased to 180°, averaging 3-6 dB greater behind (mean 130 dB) than directly in front of the fish. This pattern is consistent with the hypothesis that sound energy is reduced at the fish's ears. The source level and fundamental frequency of the boatwhistle were highly stereotyped, with coefficients of variation averaging less than 1%, and duration was more variable, with a coefficient of variation of 8%. Grunt levels overlapped but were slightly lower than boatwhistle values.

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