Withdrawn: Mechanical Noise Sources

Ross, Donald

doi:10.1016/b978-0-08-021182-4.50016-7

Cited by 17 publications

(27 citation statements)

References 24 publications

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“…The statistical approach of this study provided a framework to evaluate possible covariates for predicting underwater noise. Covariates differed depending on the frequency band analyzed; however, all models included speed and a measure of ship size, corroborating earlier studies that predicted higher noise levels from faster and larger ships71415. Our results expand on these previous findings by measuring noise from a modern ship-type, the container ship, measuring over a broader frequency range, and including additional covariates that describe the oceanographic setting.…”

Section: Discussionsupporting

confidence: 87%

“…Ships with tones had higher predicted noise levels in both the broad-band and high frequency octave bands (250 and 500 Hz). The cause of these tones is unknown, but may relate to propeller damage which may increase radiated noise, and potentially decrease efficiency of the propulsion system7. Identifying these ships and eliminating the cause of the tones would result in a significant reduction in noise.…”

Section: Discussionmentioning

confidence: 99%

“…At frequencies below 300 Hz, ambient noise levels are elevated by 15–20 dB when exposed to distant shipping456. Underwater ship noise is an incidental by-product from standard ship operations, mainly from propeller cavitation7. Concerns have been raised over the effects of these increased noise levels on marine life891011.…”

mentioning

confidence: 99%

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Relationship between container ship underwater noise levels and ship design, operational and oceanographic conditions

McKenna

Wiggins

Hildebrand

2013

Sci Rep

120

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Low-frequency ocean ambient noise is dominated by noise from commercial ships, yet understanding how individual ships contribute deserves further investigation. This study develops and evaluates statistical models of container ship noise in relation to design characteristics, operational conditions, and oceanographic settings. Five-hundred ship passages and nineteen covariates were used to build generalized additive models. Opportunistic acoustic measurements of ships transiting offshore California were collected using seafloor acoustic recorders. A 5–10 dB range in broadband source level was found for ships depending on the transit conditions. For a ship recorded multiple times traveling at different speeds, cumulative noise was lowest at 8 knots, 65% reduction in operational speed. Models with highest predictive power, in order of selection, included ship speed, size, and time of year. Uncertainty in source depth and propagation affected model fit. These results provide insight on the conditions that produce higher levels of underwater noise from container ships.

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Section: Discussionsupporting

confidence: 87%

Section: Discussionmentioning

confidence: 99%

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Relationship between container ship underwater noise levels and ship design, operational and oceanographic conditions

McKenna

Wiggins

Hildebrand

2013

Sci Rep

120

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“…where h is the depth of submergence in meters, N is the rotational speed of the propellor in RPM, and D is the propeller diameter in meters [100]. The relationship between the qualitative likelihood of cavitation and tip index is then given in table 3.1.…”

Section: Vehicle Noisementioning

confidence: 99%

Investigation of ocean acoustics using autonomous instrumentation to quantify the water-sediment boundary properties

Carey

Holmes

2006

The Journal of the Acoustical Society of America

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Several noise criteria methods commonly used in architectural acoustics have been quantitatively related to noise perception and task performance under a variety of ventilation systems-induced background noise conditions. Noise criteria, balanced noise criteria, room criteria, room criteria mark II, and A-weighted equivalent sound pressure level were examined. The first phase of the project included noise conditions controlled to be non-time-varying and nontonal, with neutral, rumbly, roaring, or hissy characteristics. An intermediate study examined exposure time length and types of performance tasks used. The final phase included noise conditions containing various levels of discrete tones from 120 to 595 Hz. Under each noise, subjects completed performance tasks and perception questionnaires. Results indicate task performance was significantly affected by perception of noise, but this relationship was not fully demonstrated by the criteria systems analyzed. The five criteria were generally well suited in describing subjective loudness perception, but some discrepancies in criteria spectral quality ratings and subjective perception existed. Finally, perception of annoyance changed based on the frequency and prominence of tones in noise, but these changes were not reflected in the criteria level or spectral quality ratings. Modifications to the existing criteria are recommended.

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“…Then the vibra-sound conversion formula becomes (1) 3. Vibra-sound conversion for the far-field By using the Helmholtz formula, which is shown as (3) where P(R) is a sound pressure at the receiving point R, k is a wave number, r is the distance from R to S and p is a sound pressure on S, the far-field sound pressure can be estimated from the sound pressure on the surface of the structure as2) (4) …”

Section: Introductionmentioning

confidence: 99%

Far-field radiated noise prediction using the cross-spectrum of surface vibration velocity.

Musha¹,

Sawatari

1995

J. Acoust. Soc. Jpn. (E), J Acoust Soc Jpn E

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Withdrawn: Mechanical Noise Sources

Cited by 17 publications

References 24 publications

Relationship between container ship underwater noise levels and ship design, operational and oceanographic conditions

Relationship between container ship underwater noise levels and ship design, operational and oceanographic conditions

Investigation of ocean acoustics using autonomous instrumentation to quantify the water-sediment boundary properties

Far-field radiated noise prediction using the cross-spectrum of surface vibration velocity.

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