Proceedings of Meetings on Acoustics (original) (raw)

Criteria for noise annoyance evaluation on board ships

Marine and offshore regulations about onboard noise are quite stratified and tangled, being issued by a number of international and national bodies. At the same time, many of the requirements are actually expressed in non quantitative terms and neglect parameters like noise spectra, low frequency pulsations or sound reverberation, which deeply influence the “sound wellness”. Aim of this paper is therefore to improve present requirements by introducing more meaningful noise annoyance criteria. These new criteria should be at the same time able to better express the actual reactions to noise from crew and passengers and simple enough to be widely applied on board ships. Such enhanced criteria are derived from the noise rating methods provided to rate indoor background sound in the civil engineering context. The possibility to make use of these indicators in the naval field is analyzed and some recommendations for a proper application on ships are given.

Analysis of literature data on shipboard noise

2020

The objective of this work is to perform a statistical characterization of noise onboard ships from available data in the literature, classifying the spectral noise measurements by different spaces and ship typologies. Data analysis of experimental measurements in octave bands was developed, classifying the noise into 3 categories based on International Maritime Organization (IMO) recommendations: accommodation spaces, navigation spaces, and work spaces. Additionally, the following ship typologies were considered: military or commercial. Relevant aspects were searched, such as high noise levels and low frequency (LF) noise components associated with induced vibrations. The results of the analysis show an average dB(A) noise level of 69 dB(A) but with different frequency distribution depending on space typology, in which workplaces had a higher mean value and dispersion in comparison with accommodation and navigation spaces. Mitigation of noise in ships is a very important issue and efforts must be made to reduce LF noises and sound pressure levels in general in all onboard spaces. To achieve more comfort and safety, the normative framework should be updated and modernized to include more sophisticated noise indicators that consider quality aspects of the spectrum such as vibrations and tonal components.

Evaluation of Acoustic Comfort and Sound Energy Transmission in a Yacht

Energies

After being neglected for a long time, in the last years, ships have been recognized and studied as sound emitters. The sound energy they generate impacts the outside, but it can also affect the indoor quality of life if the environments are not properly designed. In fact, acoustic comfort plays a pivotal role, particularly in recreational crafts. In the present work, room acoustics and acoustic camera measurements were performed, inside a 50 m length overall yacht, chosen as a case study in order to evaluate the acoustic comfort. The Italian classification procedure UNI 11367:2010 for buildings was applied, and results have been compared to other international comfort classes. However, all of these are based on prescription for standard buildings, and the present work highlights that they do not account for the effective ship’s acoustic issues: sound energy transfer from impacts over ceilings and sound energy leakage. While attention of shipbuilders in acoustic comfort is shown in ...

Acoustic impact of ships: noise-related needs, quantification and justification

The evaluation of the acoustic impact of ships is a complex problem, involving not only different sources but also different kinds of receivers and transmission paths. The problem of health and comfort for crew and passengers on board has been considered since a few decades, leading to quite a structured and detailed framework of Norms and Requirements. On the other hand, only in recent years a growing attention has been devoted to air-borne noise emissions outside the ship, for which requirements are not present. Underwater noise emissions have, even more recently, gained attention for their potential interference with mammals' communications and with the sophisticated use such animals make of acoustic signals for interacting with their living environment. An aim of the present work is to review the state of the art in the three areas above identified outlining the differences in the specific fields as regards: the present knowledge of the phenomena involved; the accuracy of the models available for the description of noise propagation; the accuracy of the models available for the quantification of noise effects.

Crew noise exposure on board ships and comparative study of applicable standards

Ships and Offshore Structures, 2010

In recent years, transport activities have radically increased due to globalisation, growth in wealth and freedom of movement. The shipping industry has responded to increased needs by providing flexible operations using new types of ships, equipped with novel technologies, materials and propulsion systems. Furthermore, services have been extended to new geographical areas including locations in and around populated cities. Naturally such services, in addition to the benefits, create various types of problems including noise pollution. This issue has been addressed at the European as well as the IMO (International Maritime Organization) level with the introduction of new/revised standards and limitations on noise. These statutory standards are also applicable to ships for the well-being of crew, commuters, as well as residents living around ship passageways and harbours. This paper focuses on the welfare and performance of seagoing crew working in various locations in the ships. Noise measurements carried out onboard six chemical tankers are presented and examined within the context of the IMO regulation A468 (XII) as well as the EU Directive 2003/10/EC concerning noise. After discussing the basic aspects of noise exposure, the paper investigates the differences between the EU and IMO standards and their effect on crew.

NOISE AND VIBRATIONS ON BOARD CRUISE SHIPS: ARE NEW STANDARDS EFFECTIVE

Standards on noise and vibration assessment are continously updated to be at the same time effective and reasonably applicable to ships. In order for the Rules to be of practical use it is imperative that they identify a procedure characterized by a series of prerequisites, that are easily identification of the exciting sources and repeatability of measurements. For defining more reliable assessment standards, a better understanding of the mechanism which governs the comfort perception is also necessary. In fact, passengers determine their acceptance of a cruise ship on the basis of considerations relating essentially on their perception of comfort, and among all the different factors relating to comfort, noise and vibrations are the main topics. In this framework, this paper is focussed on the technical aspects of the ISO 6954 regulation and discusses the criteria on which it is based with the aim of promoting further improvements of the Rule.

Evaluating the consequences of the new standards on noise conditions in ships

Polymer Journal, 2015

Noise is one of the main parameters to be considered to achieve a healthy indoor ambience in ferries. Therefore, the noise standards need to be more specialized and specifically based on real sampled data and case studies. In the present research, the noise levels in a ship, under different working conditions, were sampled and compared with those specified in the new and old standards. An initial study showed two main noise sources- clients and main engine- that influence other indoor environments, reducing the quality of life on board. The real-time data revealed that the maximum noise level limits set by the International Maritime Organization (IMO) in the older Resolution A.468 (XII) was mostly respected, except in areas where maintenance of the noise level was difficult, owing to the continuous influx of people, especially at the time of boarding and disembarking of the passengers and at the food self-service areas. In this sense, under the new Resolution MSC.337 (91), the maxim...

Implications and Prevention of Noise Hazards on Board Ships

Defence Life Science Journal

Seafarers are exposed to intense noise due to running of powerful gas turbines present in the engine room and in other compartments due to the operation of various sub systems that adversely affect their hearing acuity and proficiency. A large body of persons is employed in the Shipping industry and it is of paramount importance to preserve and promote health in the work place. Hence, this particular study was undertaken with a view to precisely quantify the noise levels associated with the operation of turbine engines and examine the impact of exposure on hearing sensitivity of the individuals. The preventive measures that can control the adverse effects like the use of ear defenders, and, supplementation of carbogen, a mixture of 5% CO2 and 95% O2 were examined

Analysis of noise on board a ship during navigation and manoeuvres

In the present study, full-scale noise levels measurements on board a Ro-Pax ferry have been carried out in various compartments of the ship, both in stationary conditions (navigation) and during manoeuvres. Noise levels have been surveyed in various categories of spaces located in all decks accessible to both passengers and crew, with the purpose of giving a complete and effective picture of the acoustic climate on board. The measured noise levels have been compared with current and proposed limits for working and living spaces, obtaining a clear identification of the most critical spaces on board the ship both in respect to acoustic comfort and noise exposure of crew during working hours. In cabins, different operating conditions for air conditioning have been tested, to analyse the specific contribution to annoyance of the ventilation noise, which turned out to be in many cases determinant. Transient conditions during manoeuvres entering and leaving harbours have been analysed by spectral time histories in cabins and public spaces close to the main propulsion plant and to bow thrusters. These situations correspond to considerably high levels, which may limit significantly operation during night time.

Normative framework for ship noise: Present and situation and future trends

Noise Control Engineering Journal, 2012

The paper addresses the present regulatory framework regarding ship noise 5 emissions both towards the internal spaces onboard and the external environ-6 ment (in air and in water). A different level of development has been reached 7 in the various areas for the definition of the needs for the noise control and 8 for their implementation in a normative framework. This is due in part to the 9 different point in time in which the different aspects were recognised to be 10 relevant and therefore studied, assessed and regulated. The analysis of existing 11 regulations is the basis for considering the present situation, on-going develop-12 ments and possible future trends as regards the evaluation of ship noise impact 13 on the various types of environment. The situation of the requirements developed 14 for the maritime field appears to be in line with other fields of engineering as 15 regards the definition of noise limits for the working environment, while the 16 definition of comfort of living on board seems to be somehow lacking behind 17 other fields, with possibility of taking advantage of their experience. Well estab-18 lished assessment procedures for external radiation in air appear to be not yet 19 available and in this case a need for specific developments arises. Finally, 20 for underwater noise emissions, there is availability of relatively well developed 21 requirements, that however are not adequately correlated to the quantification 22 42 harbours, while underwater noise affects the ocean envi-43 ronment and the marine fauna. Recent studies suggest 44 that a large percentage of people living in urban areas 45 close to harbours R1 1 and a number of marine species, at 46 different evolutionary levels R2 2 , suffer from ship noise 47 emissions. Underwater noise emissions are clearly typi-48 cal of ships and pose specific questions, given the differ-49 ent transmission medium and the different kind of 50 receivers, but the other aspects of the assessment of 51 the ship noise impact, too, have peculiar characteristics 52 in comparison with other vehicles, related to the dimen-53 sions and complexity of the ship structure, to the variety 54 of sources and operational conditions on board, to the 55 relative positions of sources and people affected and to 56 the generally higher time duration of exposures (for 57 internal noise). 58