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Nov 1976

Volume 60, Issue S1, pp. S1-S125

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back to top Session Q. Noise III: Airborne Noise Control in Maritime Structures
Contributed Papers
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Noise on dredging ships and auxiliary vessels (A)

R. W. Heymann, F. Z. Sachs, and E. P. Fortino

J. Acoust. Soc. Am. Volume 60, Issue S1, pp. S36-S36 (1976); (1 page)

Online Publication Date: 11 Aug 2005

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High noise aboard dredges and auxiliary vessels is for the most part attributable to diesel engines. Diesels are used in dredges for propulsion, dredging pump operation, and electrical generation. High diesel noise is as a rule confined to the diesel compartments. Other potentially high‐noise sources are the ventilation system; and various mechanical equipment such as conventional and hydraulic pumps, motors, and compressors. Sources other than diesel and ventilation systems produce high noise only in their immediate vicinity. With personnel confined to dredges, hearing conservation criteria must account for 24‐hour‐per‐day exposure as well as an 8‐hour‐per‐day workspace exposure. Approaches for noise control depend on whether a ship is being retrofitted or newly designed. Costs are important. For new designs, isolation of diesels and personnel within separate compartments and judicious location of noise‐producing equipment with respect to quarters are effective control methods. For existing dredges, personnel boothes are an effective solution. Ventilation noise is reduced with conventional building industry approaches of duct linings and silencers. Sealed passenger compartments and acoustically treated engine compartments are utilized on launches and auxiliary vessels.
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Development of the Proposed Canadian Noise‐Level Regulations For Vessels Engaged in Towing (A)

K. D. Harford and C. W. Wakefield

J. Acoust. Soc. Am. Volume 60, Issue S1, pp. S36-S37 (1976); (2 pages)

Online Publication Date: 11 Aug 2005

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The paper will describe the towboat noise‐control experiments, noise‐level survey, and general rationale behind the Proposed Canadian Noise‐Level Regulations for Vessels Engaged in Towing (1975). The proposed regulations are based on what was determined to be the technically feasible noise levels for the large majority of British Columbia vessels at the time of the study with provisions for reduced levels for vessels constructed in the future when marine‐noise‐control practices will have advanced and become more widely adopted. The relative importance of airborne and structure‐borne noise transmission aboard towboats and the significance of this relation to the general philosophy of towboat noise control will be discussed.
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Recommended maximum noise and vibration levels on ships (A)

A Schwartz, P. Munch, and L. Naim

J. Acoust. Soc. Am. Volume 60, Issue S1, pp. S37-S37 (1976); (1 page)

Online Publication Date: 11 Aug 2005

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With the intention to incorporate it in a revised version of the “Regulations for the Prevention of Harmful Noise on Ships (1972)” a special “Notice to Shipowners and Shipbuilders” (SHN 4/76) was prepared by a technical committee and issued by the Ministry of Transport, Department of Shipping and Ports. The recommended maximum Noise Rating Levels (NR), for existing ships and for new ships, respectively, are navigating bridge and radio room 65/60, crew cabins 65/55, mess and recreation room 75/65, general machinery spaces 85/85, engine control room 75/70, and engine workshop 80/75. The maximum recommended acceleration m/sec2—overall values from 2 to 8000 Hz), for vertical and horizontal acceleration, respectively, are: crew cabins, mess and recreation rooms 0.4/0.2, general machinery spaces 2.0/1.0 and engine control room 0.6/0.3.
Invited Papers
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Airborne noise control in maritime structures—an overview (A)

D. L. Nelson and D. P. Lewis

J. Acoust. Soc. Am. Volume 60, Issue S1, pp. S37-S37 (1976); (1 page)

Online Publication Date: 11 Aug 2005

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Similarities and differences of shipboard airborne noise problems and problems of noise in buildings, industrial plants, and transportation systems are discussed. Various types of shipboard environments are considered: these include machinery spaces, living compartments, office, command/control rooms, and deck stations. Criteria reflecting the different operational requirements are presented. Some special problems unique to ships are unusual noise sources such as active sonar ping and cavitating propellers, close proximity of personnel to major machinery, and ship structure as a significant sound‐transmission path. Methods of noise control are subject to constraints not common to other branches of acoustics. These include space and weight limitations as related to craft performance, machinery operation, and maintenance. Materials and constructions used in land‐based applications may be inappropriate in the maritime environment, because of fire hazards and contamination by oils. fuels, or salt water. The range of current activities in shipboard airborne noise control is outlined and the major deficiencies in the state of the art are discussed.
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Analytic techniques for shipboard structure‐borne noise control (A)

D. Feit

J. Acoust. Soc. Am. Volume 60, Issue S1, pp. S37-S37 (1976); (1 page)

Online Publication Date: 11 Aug 2005

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Ships like many other modern forms of transportation have become noisier through the years. This is in no small part due to propulsion equipment working at higher horsepowers and pressures and oftentimes packaged more densely into lighter, more efficient structures which can unfortunately be acoustically more transparent. The primary path of sound transmission through ships is via structural waves which propagate throughout the ship's structure. These waves are first generated by the acoustic energy of the machinery source coupling with the adjacent structure or directly via vibrations generated by forces transmitted through the machinery bearings. The ship's structure then provides an efficient transmission medium for sound energy to propagate from one part of the ship to another. The present paper describes the analytical tools that are available to the shipboard noise‐control engineer to deal with the structure‐borne noise and vibration isolation design problems.
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Overview of recent research—summary of the 1976 International Symposium on Shipboard Acoustics (A)

Miguel C. Junger

J. Acoust. Soc. Am. Volume 60, Issue S1, pp. S37-S37 (1976); (1 page)

Online Publication Date: 11 Aug 2005

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Recent Legislation in Europe on permissible noise levels in commercial shipping has heightened concern and increased research efforts to solve noise‐control problems. Technisch Physische Dienst TNO‐TH, Delft, Netherlands, has organized an international symposium of invited speakers on this topic in order to encourage dissemnation of new research results. In this summary of the conference by this participant, some of the more significant research results will be discussed. Results will be selected with regard to their expected significance for influencing the design of new commercial ships or modifications of existing ships.
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Correlation of predicted versus measured sound levels in naval surface ships (A)

Samuel Feldman

J. Acoust. Soc. Am. Volume 60, Issue S1, pp. S38-S38 (1976); (1 page)

Online Publication Date: 11 Aug 2005

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The U. S. Navy and U. S. Coast Guard have jointly sponsored the development of an airborne noise prediction procedure for military surface ships, which was published in a report entitled “Handbook for Shipboard Airborne Noise Control” dated 13 February 1974. This paper is based on a study aimed at verifying the “Handbook” prediction procedure by comparison with full‐scale, shipboard measurements. The U. S. Navy Spruance Class Destroyer (DD 963) offered an excellent opportunity for making such comparison. During the design phase, predictive calculations of sound pressure levels were made for all manned spaces. During the trials period airborne noise measurements were made in these spaces. The paper compares predicted versus measured sound levels in a limited number of spaces and also examines the source sound power level prediction formulae against measured power levels for various types of machinery. On the basis of this one ship sampling, reasonably good correlation was demonstrated between the predicted and measured sound pressure levels.
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Noise control in boats and small ships (A)

J. I. Smullin

J. Acoust. Soc. Am. Volume 60, Issue S1, pp. S38-S38 (1976); (1 page)

Online Publication Date: 11 Aug 2005

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Noise‐control problems in boats and small ships are shown to differ from those of other ship classes due to geometrical scaling laws for person occupied spaces, and by high power to displacement ratios common to them. For the fastest boats, noise sources from propeller cavitation, flow, and spray noise have pronounced importance. Obstacles to noise‐reduction techniques outlined are sensitivity of boat performance to weight, expected seaway induced acceleration loads, and corrosive effects of salt environment. Criteria for noise control are presented based on ship function: pleasure/work and continuous running/intermittent operation. Examples illustrating the general problem include measured machinery foundation impedance and vibration mount effectiveness, measured transfer functions for structure‐borne noise. Examples of noise‐control techniques include measured results with lightweight joiner‐work partitions, isolation of interior trim from hull shell, and successful use of structural damping materials.
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Noise‐control design problems of air cushion vehicles (ACV) and surface effect ships (SES) (A)

M. E. Dvornak

J. Acoust. Soc. Am. Volume 60, Issue S1, pp. S38-S38 (1976); (1 page)

Online Publication Date: 11 Aug 2005

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A description of SES and ACV design features which make these craft/ships unique from conventional displacement type ships are presented. The uniqueness of the SES/ACV designs are shown to present new problems relative to ship acoustical design. The impact of the SES/ACV design features on the source‐receiver acoustic environment are defined as well as the airborne and structure‐borne noise paths between the noise sources and receivers. Examples of test measurements made on SES/ACV type craft are presented to show the contribution of the various noise sources to the total noise at a particular location. The primary noise problem on SES/ACV type craft are shown to be predominately in the low‐frequency region. The noise criteria utilized in the design of SES/ACV's are also examined. Noise‐control design approaches which address the various noise sources on SES/ACV's are presented relative to meeting the established noise criteria. Lastly, SES/ACV noise‐control design approaches are compared to those utilized for land‐based applications.
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Noise exposure and control on fixed marine structures (A)

S. H. Judd

J. Acoust. Soc. Am. Volume 60, Issue S1, pp. S38-S38 (1976); (1 page)

Online Publication Date: 11 Aug 2005

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Machinery noise sources on drilling and producing platforms include engines, turbines, gears, generators, pumps, and compressors. Noise transmission is both structure borne and airborne. Exposure evaluation requires consideration of work shifts ranging up to 12 hours per day, seven days in a row, as contrasted to the typical on‐shore 40‐hour work week. Exposure time is not limited to the work shift for those who must live on the structure. The design problem is to avoid or eliminate excessive noise levels. If this is not feasible, noise levels are minimized both as to intensity and the physical area affected by use of quiet machinery. Enclosure and/or other acoustical treatment is then used to bring exposure within acceptable limits. Off‐duty areas and crew quarters are placed in the quietest available location, and isolated from structure‐borne and airborne noise. Examples of noise sources and control measures are illustrated by case histories.
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