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STANDARDS RESPECTING NOISE CONTROL AND HEARING PROTECTION IN CANADIAN TOWBOATS OVER 15 TONS, GROSS TONNAGE

1. AIM OF THE STANDARDS ^

1.1 The aim of these Standards is to limit maximum sound levels and to reduce exposure to noise in order to:

1. protect the crew from the risk of noise-induced hearing loss;
   
   
2. provide the crew with acceptable conditions for recuperation from the effects of exposure to high sound levels; and
   
   
3. provide for safe working conditions by giving consideration to the need for speech communication.

1.2 Where it is reasonable and practicable to do so, it is recommended that the sound levels be reduced to values lower than those specified in these Standards to further reduce the risk referred to in 1.1(a).

1.3 The limits set out in these Standards should be regarded as maximum acceptable levels. As more scientific information becomes available, consideration should be given to amending these Standards accordingly.

2. DEFINITIONS ^

2.1 In these Standards the following definitions shall apply:

"crew" includes the master, officers, seamen and apprentices of a ship;
"existing ship" means any ship that is not a new ship;

"new ship" means a ship whose construction was started on or after January 1, 1982, or which was registered in Canada on or after that date;

"ship" means every towboat over 15 tons, gross tonnage, not engaged in the salvage of logs;

"sleeping cabins" means the sleeping rooms required by the "Towboat Crew Accommodation Regulations";

"noise" means unwanted sound;

"noise-induced hearing loss" means a permanent hearing loss attributable to the effects of noise;

"sound level" means the A-weighted sound pressure level, as determined with a sound level meter or other suitable instrument;

"sound pressure level" in decibels (dB) is defined as 20 times the logarithm to the base ten of the ratio of a sound pressure to the reference pressure. For the purposes of these Standards, the reference pressure is 20 micropascals (or 2 x 10^-5 N/m²) and does not depend on frequency or time weighting;

"A-weighted sound pressure level" in decibels (dB or dB(A)) is 20 times the logarithm to the base ten of the ratio of sound pressure, weighted in accordance with the frequency weighting A, to the reference pressure;

"equivalent continuous sound levels in decibels" is defined as follows:

where

P_A(t) is the instantaneous A-weighted sound pressure in pascals (note that P_A is a function of time t, measured in seconds);

P_o is the reference sound pressure of 20 micropascals (or 2 x 10_-5 N/m²); and

T_m is the integration time interval in seconds.

(Note - The equivalent continuous sound level (L_Aeq) can be regarded as the steady A-weighted sound pressure level which, over the integration period T_m, would cause the same A-weighted sound energy to be received as that caused by the actual (fluctuating) A-weighted sound pressure P_A(t) existing during the integration period. Typical intergration periods are 1 minute, 10 minutes, 1 hour, 4 hours, 8 hours and 24 hours.)

3. APPLICATION ^

3.1 Subject to the provisions of 3.2, these Standards shall apply to new and existing ships over 15 tons, gross tonnage.

3.2 The maximum sound level specified in 4.3 shall apply to new ships only.

3.3 These Standards apply to ships in service, i.e., in port or at sea with crew on board.

4. ACCEPTABLE MAXIMUM SOUND LEVELS ^

1. 4.1 Any crew member entering any space of the ship where the sound level is 85 dB(A) or more shall use a hearing protector of appropriate quality (Class A, B or C as defined in CSA Standard Z94.2-1979), as follows:
2. in spaces where the level is not in excess of 95 dB(A), the protector shall be of Class A, B or C;
3. in spaces where the level exceeds 95 dB(A) but is not in excess of 100 dB(A), the protector shall be of Class A or B;
4. in spaces where the level exceeds 100 dB(A), the protector shall be of Class A.

4.2 For existing ships the equivalent continuous sound level in sleeping cabins shall not exceed 75 dB(A).

4.3 For new ships the equivalent continuous sound level in sleeping cabins shall not exceed 70 dB(A).

5. MEASUREMENT OF SOUND LEVEL ^

5.1 When a new ship is completed, or as soon as possible thereafter, measurements of sound level shall be taken under the operating conditions specified in 5.4 and be suitably recorded.

5.2 In existing ships, sufficient measurements of sound level shall be taken as soon as possible under the operating conditions specified in 5.4 and shall be suitably recorded.

5.3 In the case of new and existing ships, measurements of sound level shall be taken and recorded

1. whenever a major refit or conversion is undertaken, and
   
   
2. at each quadrennial or quinquennial inspection, as applicable to the ship, following the initial measurements.

5.4 The condition of the ship during the measurement of sound level shall be as follows:

1. ship in full working condition with engine controls set at full ahead;
   
   
2. all continuously operating auxiliary machinery functioning normally;
   
   
3. ventilation and air conditioning systems operating normally;
   
   
4. at least 75% oil fuel and water on board; and
   
   
5. all cabin doors, windows and sidelights closed during measurements in cabins.

5.5 During the measurement of sound level, as required in 5.4, the sea state, wind, rain, depth of water and other environmental conditions that may influence sound level readings shall be recorded.

5.6 Measurements of sound level in accordance with 5.4 and 5.5 shall be entered on a form, as shown in Appendix A of these Standards, which shall be retained on board the ship.

5.7 The measured sound levels shall be A-weighted sound pressure levels taken with:

1. a Type (Category P), Type 1 (Category N), Type 2 (Category P) or Type 2 (Category N) instrument as specified in the standard for Integrating-Averaging Sound Level Meters now in preparation in Working Group 11, Technical Committee No. 29, Sub-Committee 29C of the International Electrotechnical Commission, or other equivalent standard; or
   
   
2. a Type 1, Type 1 I, Type 2 or Type 2 I instrument as specified in International Electrotechnical Commission Publication 651; Sound Level Meters (First Edition, 1979), American National Standard: Specification for Sound Level Meters (Revision of ANSI S1.4-1971) now in preparation in ANSI Working Group S1-45 of the Acoustical Society of America, or other equivalent standard.
   
   When the instrument is an integrating-averaging sound level meter the equivalent continuous sound level (L_Aeq) shall be measured with an integration time interval chosen to give a reading fully representative of the sound level in the space.
   
   When the fluctuations in sound level are no greater than 6 dB, the sound level may be measured with a sound level meter with S time weighting (i.e., "slow" response). A measuring period of at least ten seconds shall be allowed for each reading, and an estimate of level made by averaging the excursions of the meter needle by eye. When the fluctuations in level are between 4 and 6 dB, the estimated average level shall be increased by 1 dB.
   
   In the event of disagreement, reference measurements shall be made with a Type 1 (Category P) integrating-averaging sound level meter or a Type 1I sound level meter.
   
   Notes: (i) Pending the publication of the IEC standard for integrating-averaging sound level meters referred to in 5.7(a), such instruments shall comply with the draft document dated July 1981.
   
   (ii) Pending the publication of the revision of ANSI S1.4-1971 referred to in 5.7(b), the draft document ANSI S1.4-198X may be used.

5.8 In cabins and spaces of similar size, sound level measurements shall normally be taken in the centre of the room at normal ear height (1.2 to 1.5 m). The microphone shall be moved horizontally and/or vertically over a distance of approximately 1 metre (i.e., swung on 0.5 m radius) to provide spatial averaging during the measurement.

In larger spaces, where sound levels may vary considerably within the space, readings shall be taken at intervals not greater than 3 m throughout the space, including positions of maximum sound level.

5.9 Sound levels need not be recorded for normally unoccupied spaces and deck areas that are remote from sources of noise and where a rough check shows that the sound levels are well below 85 dB(A).

5.10 Unless specifically required, the measurements shall not normally be taken closer than 1 metre from decks, bulkheads or other major surfaces.

5.11 In machinery spaces, readings shall not normally be taken at distances less than 1 metre from operating machinery, decks, bulkheads or other major surfaces, inlets and exhausts. Where this is not possible, measurements shall be taken at a position mid-way between the machine and the adjacent reflecting surface. Measurements of noise from inlet and exhaust openings shall be taken at positions located 30° to the direction of flow to avoid influencing the readings by low frequency turbulence in the gas stream. Measurements shall be made at a height 1.2 to 1.5 m above the deck, platform or walkway as follows:

1. in single screw engine rooms, one measurement forward and one measuremnt aft of the main engine; and
   
   
2. in twin screw engine rooms, the measurement shall be taken at a position midway between the engines.

5.12 The batteries and calibration of the measuring instrument shall be checked immediately before and after each period of use. During measurements of sound level, only those persons necessary for the operation of the ship and those persons taking the measurements shall be present in the space concerned, which shall be furnished to the normal seagoing standard.

6. HEARING TESTING PROGRAM ^

6.1 Every crew member of a ship to which these Standards apply shall undergo an annual hearing test and the results shall be recorded. Testing programs, acceptable to the Director, Ship Safety Branch, shall be established. Such programs shall be under the supervision of a certified audiologist or a medical practitioner duly qualified in the hearing field, who shall also have the responsibility for interpreting the test results.

APPENDIX A ^

Name of Ship:

Official Number:

Port of Registry:

Owner:

Registered Length:

Gross Tonnage:

Engine Make and Rating:

Main Engine Revolutions at Time of Test:

Were the engine controls set full ahead?

Fuel and water on board (at least 75% of total capacity)

Was all continuous operating auxiliary
machinery functioning normally?

Were ventilation and air conditioning
systems operating normally?

Were all doors, windows and sidelights
of the space closed?

Depth of water under the ship at time of test:

Sea State:

Wind:

Rain:

Other environmental conditions that
may influence readings:

SOUND LEVEL MEASUREMENTS ^

Make, type and serial number of sound level meter:

Duration of measurement (integration period):

Was the measuring instrument calibrated
immediately before and after the
recording of measurements?

Sound level measurements taken by:

Sound level measurements witnessed by:

Date of Test:

Additional Comments or Remarks:

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