NtS 213/1987 Recommendations on Noise Levels on Board Ships*

Chapter 1 General

1.1 Scope

1.1.1 The provisions of this Annex provide standards to prevent the occurence of potentially hazardous noise levels on board ships and to provide standards for an acceptable environment for seafarers.
1.1.2 Provisions are made for:
.l protecting the seafarer from the risk of noise-induced hearing loss under conditions where at present it is not feasible to limit the noise to a level which is not potentially harmful;
.2 measurement of noise levels and exposure; and
.3 limits on acceptable maximum noise levels for all spaces to which seafarers normally have access.

1.2 Purpose

1.2.1 The purpose of the provisions of this Annex is to limit noise levels and to reduce exposure to noise, in order to:
.1 provide for safe working conditions by giving consideration to the need for speech communication and for hearing audible alarms, and to an environment where clear-headed decisions can be made in control stations, navigation and radio spaces and manned machinery spaces;
.2 protect the seafarer from excessive noise levels which may give rise to a noise-induced hearing loss; and
.3 provide the seafarer with an acceptable degree of comfort in rest, recreation and other spaces and also provide conditions for recuperation from the effects of exposure to high noise levels.

1.3 Application

1.3.1 The provisions of this Annex apply to ships with seafarers on board in port condition or at sea, for which the construction contract has been entered into on or after 1 February 2000, provided that the provisions of this Annex only apply to ships of less than 1,600 tons gross tonnage, as far as reasonable and practicable, to the satisfaction of the Head of the Shipping Inspectorate.
1.3.2 The provisions of this Annex also apply to ships with seafarers on board in port condition or at sea, not being dynamically supported craft, pipe-laying barges, crane barges, dredging material, mobile offshore drilling units and ships not propelled by mechanical means:
a. of 1,600 tons gross tonnage and over for which the construction contract has been entered into in the period of 1 August 1987 up to 31 January 2000;
b. of less than 1,600 tons gross tonnage for which the construction contract has been entered into in the period of 1 August 1987 up to 31 January 2000, as far as reasonable and practicable, to the satisfaction of the Head of the Shipping Inspectorate;
c. of 1,600 tons gross tonnage and over for which the construction contract has been entered into before 1 August 1987, as far as the provisions relate to potentially hazardous noise levels and as far as reasonable and practicable, to the satisfaction of the Head of the Shipping Inspectorate.
1.3.3 For ships designed for and employed on voyages of short duration, or on other services involving short periods of operation of the ship, sections 4.2.3 and 4.2.4 may be applied only with the ship in port condition, provided that the periods under such conditions are adequate for seafarers' rest and recreation.
1.3.4 The provisions of this Annex do not apply to passenger cabins and other passenger spaces, not being work spaces.

1.4 Definitions

For the purpose of this Annex the following definitions apply:

1.4.1Accommodation spaces : cabins, offices, hospitals, mess rooms, recreation rooms (such as lounges, smoke rooms, cinemas, libraries and hobbies and games rooms) and open recreation areas to be used by seafarers.

1.4.2Auxiliary machinery : machinery other than main propelling machinery that is in service when the ship is in normal service, e.g. diesel engines, turbo-generators, hydraulic motors and pumps, compressors, boiler ventilation fans and gear pumps.

1.4.3A-weighted sound pressure level or noise level : the measured or calculated sound level, expressed in dB(A) according to the relevant rules established by the International Electronic Commission,

1.4.4Continuously manned spaces : spaces in which the continuous or prolonged presence of seafarers is necessary for normal operational periods.

1.4.5Crane barge : a vessel with permanently installed cranes designed principally for lifting operations.

1.4.6Duty stations : the spaces in which the main navigating equipment, the ship's radio or the emergency source of power are located or where the fire recording or fire control equipment is centralized and also those spaces used for galleys, main pantries, stores (except isolated pantries and lockers), mail and specie rooms, workshops other than those forming part of the machinery spaces and similar spaces.

1.4.7Dynamically supported craft : a craft which is operable on or above water and which has characteristics different from those of conventional displacement ships and which also complies with either of the following characteristics:
.1 the weight, or a significant part thereof, is balanced in one mode of operation by other than hydrostatic forces; and
.2 the craft is able to operate at speeds such that the function VgL is equal to or greater than 0,9,
where v = the maximum speed in m/s,
L = the water-line length in m
and g = the acceleration due to gravity in m/s2.

1.4.8Ear protector : a device worn to reduce the level of noise heard by the wearer.

1.4.9 Not included.

1.4.10Equivalent continuous sound level Leq (H) : a notional level which would in the course of a given time period (H) cause the same A-weighted sound energy to be received as that due to the actual sound over the period.
where T = measurement time
Pa(t) = A-weighted instantaneous sound pressure
Po = 20 x 10-6 pascal (reference level)

1.4.11 (Cancelled)

1.4.12Fluctuating noise : noise which is varying in level rising and falling. It may be taken to mean fluctuations in excess of the steady noise as defined in 1.4.31 and excludes impulse noise as defined in 1.4.14.

1.4.13Hearing loss : hearing loss is evaluated in relation to a reference auditory threshold defined conventionally in ISO Standard 389 (1975). The hearing loss corresponds to the difference between the auditory threshold of the subject being examined and the reference auditory threshold. ISO Standard 1999 (1975) takes an average loss of 25 dB calculated at frequencies 500, 1,000 and 2,000 Hz.

1.4.14Impulse noise : noise of less than one second's duration which occurs as an isolated event, or as one of a series of events with a repetition rate of less than 15 times per second.

1.4.15Integrating sound level meter : a sound level meter designed or adapted to measure the level of the mean squared time averaged A-weighted sound pressure.

1.4.16 ISO noise rating (NR) number : the number found by plotting the octave band spectrum on the NR curves given in ISO Standard R 1996-1971 and selecting the highest noise rating curve to which the spectrum is tangent.

1.4.17Machinery spaces : all spaces containing propulsion machinery, boilers, oil fuel units, steam and internal combustion engines, gas turbines, generators and major electrical machinery, oil filling stations, refrigerating, stabilizing, ventilation and air-conditioning machinery and similar spaces, and trunks to such spaces.

1.4.18Mobile offshore drilling unit : a vessel capable of engaging in drilling operations for the exploration for, or exploitation of, resources beneath the sea-bed, such as liquid or gaseous hydrocarbon, sulphur or salt.

1.4.19Navigating bride wings : those parts of the ship's navigating bridge extending towards the ship's sides.

1.4.20 Noise: all sound which can result in hearing impairment, or which can be harmful to health or be otherwise dangerous.

1.4.21Noise induced hearing loss : hearing loss, originating in the nerve cells within the cochlea, attributable to the effects of sound.

1.4.22Noise level : see A-weighted sound pressure level (1.4.3).

1.4.23Propulsion power : the maximum continuous power specified by the manufacturer of the propulsion machinery.

1.4.24Occasional exposures : those exposures typically occurring once per week, or less frequently.

1.4.25 Passengers: all persons on board other than:
1e. the master and members of the crew;
2e. other persons employed or engaged in any capacity on board a ship on the business of that ship;
3e. children which on the day of embarkation have not yet reached the age of one year.

1.4.26Pipe-laying barge : a vessel specifically constructed for, or used in conjunction with, operations associated with the laying of submarine pipelines.

1.4.27Port condition : the condition in which all machinery solely required for propulsion is stopped.

1.4.28Potentially hazardous noise levels : those levels at and above which persons exposed to them without protection are at risk of sustaining a noise induced hearing loss.

1.4.29 Sound: energy that is transmitted by pressure waves in air or other materials and is the objective cause of the sensation of hearing.

1.4.30Sound pressure level : a measure of sound level L, on a logarithmic scale given by:
L = 20 lg (p/po) dB
where p = rms value of measured sound pressure between 20 Hz and 20 kHz
po = 20 x -6 pascal (reference level)

1.4.31Steady noise : a sound where the level fluctuates through a total range of less than 5dB(A) as measured on the 'slow' response of a sound level meter in one minute.

1.4.32Voyages of short duration : voyages where the ship is not generally underway for periods long enough for seafarers to require sleep, or long off-duty periods, during the voyages.

1.4.33Dredging material : any ship which because of its construction and design is solely intended for performance of or for the use for the benefit of contractor works of a hydraulic sort.

Chapter 2 Measurement

2.1 General

On completion of the construction of a ship, or as soon as practicable thereafter, measurement of noise levels in all spaces specified in Chapter 4 should take place under the operating conditions specified in 2.2 and 2.3 and should be suitably recorded as required by 4.3.

2.2 Operating conditions at sea

2.2.1 Measurement should be taken with the ship in the loaded or ballast condition.

2.2.2 The main propulsion machinery should be run at a service shaft speed of at least eighty percent. When the propulsion machinery has been valuated and set at a shaft speed lower than 80 percent of the propulsion power by the Head of the Shipping Inspectorate, the lower shaft speed should be developed. Controllable pitch and Voith-Schneider propellers, if any, should be in the normal seagoing position.

2.2.3 All auxiliary machinery, navigation instruments, radio and radar sets, etc., normally, or likely to be, in use at any one time should operate throughout the measurement period.

2.2.4 Measurements in spaces containing emergency diesel engine-driven generators, fire pumps or other emergency equipment that would normally be run only in emergency, or for test purposes, should be taken with the equipment operating. Adjoining spaces need not be measured with such equipment operating, however, unless it is likely that the equipment will be operated for periods other than those mentioned above.

2.2.5 Mechanical ventilation and air-conditioning equipment should be in normal operation, taking into account that the capacity should be in accordance with the design conditions.

2.2.6 Doors and windows should in general be closed but they should be open in spaces where this is the normal condition, for instance in the navigating bridge where the door on the lee side is normally open.

2.2.7 Spaces should be furnished with all necessary equipment. Measurements without soft furnishings may be made but no allowance should be made for their absence.

2.2.8 Ships fitted with bow thrusters, stabilizers, etc., may be subject to high noise levels when in operation. Measurements should be taken at positions around such machinery when in operation and in adjacent accommodation spaces and duty stations.

2.3 Operating conditions in port

2.3.1 Measurements as specified in 2.3.2, 2.3.3 and 2.3.4 should be taken with the ship in port condition.

2.3.2 Measurements should be taken with the ship's cargo handling equipment in operation, in those areas and accommodation spaces affected by its operation. Noise originating from sources external to the ship should be discounted as indicated in 2.4.3.

2.3.3 Where the ship is a vehicle carrier and noise during loading and discharging originates from vehicles, the noise levels in the cargo spaces and the duration of the exposure should be measured. This exposure should be considered in conjunction with Chapter 5.

2.3.4 It will be necessary to take measurements in machinery spaces with the auxiliary machinery operating in the port condition if the provisions of 5.3.1 in respect of ear protection are to be met in lieu of the provisions of 4.2.1.1 during maintenance, overhaul or similar port conditions.

2.4 Environmental conditions

2.4.1 The depth of water under the ship's keel and the presence of large reflecting surfaces in the ship's vicinity may affect the readings obtained, and should, therefore, be noted in the noise survey report.

2.4.2 The meteorological conditions such as wind and rain, as well as sea state, should be such that they do not influence the measurements. Wind force 4 and sea state 3 should not be exceeded. If this cannot be achieved, the actual conditions should be reported.

2.4.3 Care should be taken to see that noise from extraneous sound sources, such as people, construction and repair work, does not influence the noise level on board the ship at the positions of measurement. If necessary, readings may be corrected for steady state background noise according to the energy summation principle.

2.5 Safe measurement conditions

With the meter set to 'fast response' spot checks should be made at positions of high noise level to ensure the safety of a person taking measurements.

2.6 Measurement procedures

2.6.1 During noise level measurement, only seafarers necessary for the operation of the ship and persons taking the measurements should be present in the space concerned.

2.6.2 Sound pressure level readings should be taken in decibels using an A-weighting filter (in dB(A)) and if necessary also in octave bands between 31.5 and 8,000 Hz, in order to determine the ISO noise rating (NR) number, as required by Chapter 4.

2.6.3 The meter should be set to 'slow' response and the readings made only to the nearest decibel. A measuring time of at least 5 seconds should be allowed. If a meter fluctuates in level within a range of no more than 5 dB (A) maximum to minimum, an estimate of the level should be made by averaging the excursions of the needle by eye or otherwise.

2.6.4 If the range of fluctuations are in excess of 5 dB(A), or the sound is cyclic, irregular or intermittent in operation an integrating meter should be used set to A-weighting. Integration should be made over a period of at least 30 seconds.

2.6.5 Exposure measurement
In addition to the steady state and fluctuating noise level measurements, the noise exposure of seafarers may be measured as allowed by 4.1.2, if necessary.

2.7 Calibration

The sound level meter should be calibrated with the calibrator referred to in 3.2.2 directly before and after measurements are taken.

2.8 Measurement positions

2.8.1Points of measurement
If not otherwise stated, measurements should be performed with the microphone at a height of between 1.2 and 1.6 m from the deck. The distance between two measurement points should be at least 2 m, and in large spaces not containing machinery, measurements should be taken at intervals not greater than 7 m throughout the space including positions of maximum noise level. In large cargo holds no more than three measurements need be taken. In no case should measurements be taken closer than 0.5 m from the boundaries of a space. The microphone positions should be as specified in 2.8.2 to 2.8.8.

2.8.2Accommodation spaces
One measurement should be made in the middle of the space. The microphone should be moved slowly horizontally and/or vertically over a distance of 1 m and the mean reading recorded. Additional measurements should be performed at other points if appreciable differences, i.e. greater than 10 dB(A), in the level of sound inside the room occur, especially near the head positions of a sitting or lying person.

2.8.3Machinery spaces
2.8.3.1 Measurements should be made at the principal working and control stations of the seafarers in the machinery spaces and in the adjacent control rooms, if any, special attention being paid to telephone locations and to positions where voice communication and audible signals are important.
2.8.3.2 Readings should not normally be taken closer than 1 m from operating machinery, or from decks, bulkheads or other large surfaces, or from air inlets. Where this is possible, measurements should be taken at a position midway between the machinery and adjacent reflecting surface.
2.8.3.3 Measurements from machinery which constitutes a sound source should be taken at 1 m from the machinery. Measurement should me made at a height of 1.2 m to 1.6 m above the deck, platform or walkway as follows:

1. at a distance of 1 m from, and at intervals not greater than 3 m around, all sources such as:
   - main turbines or engines at each level;
   - main gearing;
   - exhaust-gas turbines;
   - separators;
   - generators and aggregates;
   - boiler firing platform;
   - forced and/or induced draught fans;
   - compressors; and
   - cargo pumps (including their driving motors or turbines). In order to avoid an unnessarily large and impractical number of measurements and recordings in the case of large engines and of machinery spaces where the measured sound pressure level in dB(A) at the intervals above does not vary significantly, it will not be necessary to record each position. Full measurement at representative positions and at the positions of maximum sound pressure level should, however, be made and recorded, subject to at least four measurements being recorded at each level;
2. at local control stations, e.g. the main manoeuvring or emergency manoeuvring stand on the main engine and the machinery control rooms;
3. at all other locations not specified in .1 and .2 which would normally be visited during routine inspection, adjustment and maintenance;
4. at points on all normally used access routes, unless covered by positions specified under .1, .2 or .3 at intervals not greater than 10 m;
5. in rooms within the machinery space, e.g. workshops. In order to restrict the number of measurements and recordings, the number of recordings can be reduced as in .1, subject to a total of at least four measurements (including those specified in this paragraph) being recorded at each machinery space level up to upper deck.

2.8.4 Duty stations
The noise level should be measured at all points where the work is carried out. Additional measurements should be performed in spaces containing duty stations if variations in noise level are thought to occur in the vicinity of the duty stations.

2.8.5Normally unoccupied spaces
2.8.5.1 In addition to the spaces referred to in 2.8.2 to 2.8.4, measurements should be made in all locations with unusually high noise levels where seafarers may be exposed, even for relatively short periods, and at intermittently used machinery locations, for example cargo discharge pumps.
2.8.5.2 In order to restrict the number of measurements and recordings, noise levels need not be measured for normally unoccupied spaces, holds, deck areas and other spaces which are remote from sources of noise and where a preliminary survey shows that the noise levels are well below the limit specified in Chapter 4.

2.8.6Open deck
Measurements should be taken in any areas provided for the purpose of recreation and additionally where a preliminary survey indicates that the limits specified in 5.3.1 may be exceeded.

2.8.7Intake and exhaust openings
When measuring noise levels at the intake and exhaust of engines and near ventilation, air-conditiong and cooler systems, the microphone should, where possible, be placed outside the gas stream at a distance of 1 m from the edge of the intake or exhaust opening and at a 30° angle away from the direction of the gas stream and as far as possible from reflecting surfaces.

2.8.8Navigating bridge wings
Measurements should be taken on both navigating bridge wings but should only be taken when the navigating bridge wing to be measured is on the lee side of the ship.

Chapter 3 Measuring equipment

3.1 Equipment specifications

3.1.1Sound level meters
Measurement of sound pressure levels should be carried out using precision grade sound level meters, industrial grade sound level meters, and integrating sound level meters subject to the requirements of paragraph 3.1.4. Such meters should be manufactured to the IEC Publication 651 (1979)*, type 0, 1 or 2 standards.

3.1.2Octave filter set
When used alone, or in conjuction with a sound level meter, as appropriate, an octave filter set should conform to IEC Publication 225 (1966)**.

3.1.3 Microphones
Microphones should be of the random incidence type and should meet the standards of IEC Publication 179 (1973), the IEC Publication 651 (1979), class 1 or 2.

3.1.4Selection of equipment
The main difference between the grades is in the tolerance band which is allowed on the A-weighting filter networks. The tolerances allowed are wider at low and high frequencies than at mid-frequencies. In consequence, for sound emitted by typical medium sized machines the accuracy of measurement with a precision grade meter is about 1 dB(A) and with an industrial grade meter about 3 dB(A). The industrial grade meter will tend to give lower readings than the precision grade. It is recommended that where noise levels are likely to be close to the limits prescribed, precision grade instruments should be used, and in any cases of dispute readings should be taken with a precision grade instrument.

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* Recommendation for sound level meters.
** Octave, half octave and third octave band-pass filters intended for the analysis of sounds and vibrations.

3.2 Use of equipment

3.2.1Measuring fluctuating noise
When measuring fluctuating noise an integrating sound level meter should be used.

3.2.2 Calibration
A suitable calibrator, approved by the manufacturer of the particular sound level meter, should be used. Calibrators for use with precision grade sound level meters should be accurate to within about 0.3 dB(A), and for use with industrial grade meters accurate to within about 0.5 dB(A).

3.2.3Check of measuring instrument and calibrator
The sound level measuring instrument and calibrator should be returned to the manufacturer or other competent organization capable of providing a calibration check by a laboratory recognized by the Head of the Shipping Inspectoarte at intervals not exceeding two years.

3.2.4Microphone wind screen
A microphone wind screen should be used when taking readings outside, e.g. on navigating bridge wings or on deck, and below deck where there is any substantial air movement. The wind screen should not affect the measurement level of similar sounds by more than 0.5 dB(A) in 'no wind' conditions.

3.2.5Measuring equipment for use in gas dangerous spaces
Measuring equipment should not be used in areas where flammable gas/air mixtures may be present, unless such equipment has been certified intrinsically safe for such purposes.

3.2.6Industrial grade instruments
In any situations where an industrial grade meter is used a factor of 3 dB(A) should be added to the readings to allow for the reduced accuracy of this type of instrument.

Chapter 4 Maximum acceptable sound pressure levels

4.1 General

4.1.1 The limits specified in this chapter should be regarded as maximum levels and not as desirable levels. Where reasonably practicable, it is desirable for the noise level to be lower than the maximum levels specified.

4.1.2 The limit specified for any work space may be assessed by steady, fluctuating, equivalent continuous or effective sound level measurement for the space. Where the equivalent continuous or effective sound level is used, it should include all the measurement locations required in Chapter 2. Where the 24 hour equivalent continuous or effective sound level is used as the basis for compliance with the provisions, the limit for this level given in Chapter 5 should apply.

4.1.3 Personnel entering spaces with noise levels greater than 85 dB(A) should be required to wear ear protectors (see Chapter 5). The limit of 110 dB(A) given in 4.2.1.2 assumes that ear protectors giving protection meeting the requirements for ear muffs in Chapter 7 are worn.

4.1.4 Limits are specified in terms of A-weighted sound pressure levels (see 1.4.3).

4.1.5 In accommodation spaces where the dB(A) limits are exceeded and where there is a subjectively annoying low frequency sound or obvious tonal components the ISO noise rating (NR) number should also be determined. The limits specified may be considered as satisfied if the ISO noise rating (NR) number does not numerically exceed the specified A-weighted value minus 5.

4.1.6 In machinery spaces specified in 4.2.1.2, in which the operation of any equipment or machinery or part of machinery results in an emission of subjectively high frequency sound and in which the sound level of 105 dB(A) is exceeded, the ISO noise rating (NR) number should be determined. When NR 105 is exceeded the acceptability of this level should be determined by the Head of the Shipping Inspectorate.

4.2 Noise level limits

Limits for noise levels are specified for various spaces as follows:

4.2.1	Work spaces (see 5.1)	dB(A)
.1	Machinery spaces (continuously manned)*	90
.2	Machinery spaces (not continuously manned)*	110
.3	Machinery control rooms	75
.4	Workshops	85
.5	Non-specified work spaces*	90
4.2.2	Navigation spaces	dB(A)
.1	Navigating bridge and chartrooms	65
.2	Listening post, including navigating bridge wings and windows**	70
.3	Radio rooms (with radio equipment operating but not producing audio signals)	60
.4	Radar rooms	65
4.2.3	Accommodation spaces	dB(A)
.1	Cabins and hospitals	60
.2	Mess rooms	65
.3	Recreation rooms	65
.4	Open recreation areas	75
.5	Offices	65
4.2.4	Service spaces	dB(A)
.1	Galleys, without food processing equipment	75
.2	Serveries and pantries	75
4.2.5	Normally unoccupied spaces*	dB(A)
	Spaces not specified (see 5.1)	90

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* Ear protectors should be worn when the noise level is above 85 dB(A) (see 4.1.3).
** Reference is made to resolution A.343(IX) which also applies.

4.3 Survey report

4.3.1 A noise survey report should be made for each ship. The report should comprise information on the noise levels in the various spaces on board. The report should show the reading at each specified measuring point. The points should be marked on a general arrangement plan, or on accommodation drawings attached to the report, or should otherwise be identified.

4.3.2 A model format is preferably used for the survey report*.

4.3.3 The following particulars should be mentioned in the noise survey report:

1. hull number, name, gross tonnage, main dimensions and type of ship;
2. the leading particulars of the ship's machinery;
3. names of the builder and owner of the ship;
4. date and time of the measurements;
5. the type of voyage, the meteorological conditions, sea state and the ship's position during the measurements;
6. the underkeel clearance during the measurements;
7. the main operating conditions as required by 2.2 and 2.3, including those items on the main machinery line which were operating and the operating condition;
8. the name and address of those carrying out the measurements;
9. the make, type and serial number of instrumentation used; vdetails and date of calibration of instruments;
10. a list of the main noise abatement measures applied aboard the ship;
11. other particulars of interest, including exceptions to the standard laid down in these provisions.

4.3.4 A copy of the survey report should be kept on board the ship.

Chapter 5 Noise exposure limits

5.1 General

The noise level limits as set out in Chapter 4 are designed to ensure that, if they are complied with, seafarers will not be exposed to an Leq (24) exceeding 80 dB(A), i.e. within each day or 24 hour period the equivalent continuous noise exposure would not exceed 80 dB(A). In spaces with sound pressure levels exceeding 85 dB(A), it will be necessary to use suitable ear protection, or to apply time limits for exposure, as set out in this chapter, to ensure that an equivalent level of protection is maintained.

5.2 Hearing conservation and use of ear protectors

In order to comply with the exposure criteria of this chapter, the use of ear protectors complying with Chapter 7 is permitted. In some instances when ear protectors are required for compliance with this Annex, a hearing conservation programme and other measures may be implemented by the Head of the Shipping Inspectorate.

5.3 Limits of exposure of seafarers to high noise levels

Seafarers should not be exposed to noise in excess of the levels and durations shown in figure 5.1 and described in 5.3.1 to 5.3.5.

5.3.1 Maximum exposure without protection (zone E, fig. 5.1)
Seafarers without ear protection should not be exposed to noise levels exceeding 85 dB(A). When seafarers remain for more than 8 hours in spaces with a high noise level, a Leq (24) of 80 dB(A) should not be exceeded. Consequently, for at least a third of each 24 hours each seafarer should be subject to an environment with a noise level not exceeding 75 dB(A).

5.3.2 Maximum exposure with protection (zone A, fig. 5.1)
No seafarer even wearing ear protectors should be exposed to levels exceeding 120 dB(A) or to a Leq (24 exceeding 105 dB(A).

5.3.3 Daily exposure (zone D, fig. 5.1)
If seafarers routinely work (daily exposure) in spaces with noise levels within zone D ear protectors should be worn and a hearing conservation programme may be considered.

5.3.4 Occasional exposure (zone B, fig. 5.1)
Only occasional exposures should be allowed in zone B and both ear muffs and ear plugs should be used unless the exposure duration is restricted to not more than 10 minutes when only ear muffs or plugs are required.

5.3.5 Occasional exposure (zone C, fig. 5.1)
In zone C only occasional exposures should be allowed and ear muffs or plugs should be required.

5.4 24 hour equivalent continuous sound level limit

As an alternative to compliance with the provisions of 5.3 (fig. 5.1), no unprotected seafarer should be exposed to a 24 hour equivalent continuous sound level greater than 80 dB(A). Each individual's daily exposure duration in spaces requiring the use of ear protectors should not exceed 4 hours continuously or 8 hours in total.In those cases, where to the satisfaction of the Head of the Shipping Inspectorate is determined that exposures are intermittent, no unprotected seafarer should be exposed to an equivalent effective sound level Leq (24) = 85 dB(A).

5.5 Hearing conservation programme

5.5.1 The Head of the Shipping Inspectorate may provide a hearing conservation programme for seafarers exposed to the noise levels referred to in 5.3.3 in order to train them in the hazards of noise and use of ear protection, and to monitor hearing acuity.
Some elements of a hearing conservation programme are as follows:

1. periodic audiometric tests, to the satisfaction of the Head of the Shipping Inspectorate;
2. instruction of exposed persons on the hazards of high and long duration noise exposures and on the proper use of ear protectors;
3. maintenance of audiometric test records; and
4. periodic analysis of records and hearing acuity of individuals with high hearing loss.

An optional element of a hearing conservation programme is to control the 24 hour equivalent continuous or effective sound level to which individuals working in high noise level spaces are exposed. Such control requires calculation of the 24 hour equivalent continuous or effective sound level based upon the measurement of exposure durations for steady noise levels in accordance with 2.6.5 or the equivalent continuous sound level measurement for fluctuating noise in accordance with 2.6.4. If this 24 hour level does not meet the limits, the duration of exposure should be controlled or ear protectors used at appropriate times to bring the individual's exposure within the limit.

Chapter 6 Acoustic isolation between accommodation spaces

6.1 General

Consideration should be given to the acoustic insulation between accommodation spaces in order to make rest and recreation possible even if activities are going on in adjacent spaces, e.g. music, talking, cargo-handling, etc.

6.2 Sound insulation index

6.2.1 The airborne sound insulation properties for bulkheads and decks within the accommodation should comply with the following airborne sound insulation index (Rw) according to ISO Standard R 717/1-1982*.

Cabin to cabin: Rw = 30
Messrooms, recreation rooms to cabins and hospitals: Rw = 45

6.2.2 The airborne sound insulation properties should be determined by laboratory tests in accordance with ISO Standard R 14O/III** to the satisfaction of the Head of the Shipping Inspectorate.

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* ISO R717 Rating of sound insulation in buildings and building elements. Part 1: Airborne sound insulation in buildings and of interior building elements.
** ISO R140/III Laboratory measurements of airborne sound insulation and building elements.

6.3 Erection of materials

Care should be taken in the erection of materials and in the construction of accommodation spaces to ensure to the greatest practicable extent that the attenuation values specified in 6.2 are not significantly impaired.

Chapter 7 Ear protection and warning information

7.1 General

When the application of means for controlling sound at source does not reduce the noise level in any space to that specified in 4.1.3, seafarers who are required to enter such spaces should be supplied with effective ear protection on an individual basis. The provision of ear protectors should not be considered to be a substitute for effective noise control.

7.2 Recommendation for ear protectors

7.2.1 Ear protectors should provide at least the attenuation listed in table 7.1. The attenuation to be compared with that in the table should be the result of the average value of the ear protector attenuation minus the standard deviation measured in accordance with ISO Standard (DIS 4869) or a similar standard acceptable to the Head of the Shipping Inspectorate. 7.2.2 For the purpose of developing the criteria specified in Chapter 4 and section 5.3, ear protectors have been assumed to provide approximately the following insertion loss:

1. ear plugs: - 20 dB(A)
2. ear muffs: - 30 dB(A)
3. ear plugs and ear muffs: - 35 dB(A)

Therefore, care should be exercised when using ear plugs in very high noise areas (i.e. over 100 dB(A)) unless the attenuation of the plug used sufficiently exceeds the values of table 7.1 or appropriate attenuations at individual frequencies are known.

7.3 Selection and use of ear protectors

Seafarers should be instructed in the proper use of ear protectors.

7.4 Warning notices

Where the noise level in machinery spaces (or other spaces) is greater than 85 dB(A), entrances to such spaces should carry a warning notice comprising symbol and supplementary sign as presribed by the Head of the Shipping Inspectorate. If only a minor portion of the space has such noise levels the particular location(s) or equipment should be identified at eye level, visible from each direction of access.

7.5 Miscellaneous equipment

Where hand tools, galley and other portable equipment produce noise levels above 85 dB(A) in normal working conditions warning information should be provided.

Chapter 8 Prognosis

A prognosis of the noise levels of the spaces described in Chapter 4 should be drawn up.
This prognosis, together with the corresponding calculations and a summary of the acoustic measures to be taken, should be submitted to the Head of the Shipping Inspectorate on time, but at the latest in such a phase of the construction that drastic acoustic measures can still be taken.

• Informatietype: Informatie voor uitvoering
• Documentsoort: Bekendmaking aan de sector
• Toegangsrechten: Extern
• Identificatie: PUC_1156_14
• Versie: 1
• Datum beschikbaarheid: 05-07-2006
• Geldigheid van: 11-06-1987
• Wijzigingsdatum: 24-11-2016
• Titel: NtS 213/1987 Recommendations on Noise Levels on Board Ships*
• Organisatie: Inspectie Leefomgeving en Transport
• Taal: Engels
• Onderwerp: Veiligheid / Safety
• Hoofdtaak: Koopvaardij / Merchant Shipping
• Thema: Zeevaart / Seagoing ships / Mandatory Regulations / National Instruments (Mandatory) / Bekendmakingen aan de Scheepvaart / Notices to Shipping / Notices to Shipping