Purpose: The Code on Noise Levels on Board Ships (the IMO Noise Code, most recently the 2014 Code on Noise Levels) establishes a set of maximum permissible noise levels for the various spaces and work stations on board ships, to protect the hearing, health and wellbeing of seafarers and to ensure safe and comfortable accommodation and working conditions. It aims to ensure that noise in workplaces, accommodation, mess rooms, recreation spaces, and at machinery, is kept within limits that prevent hearing damage, prevent masking of essential communication/audible alarms, and enable safe rest and recreation.

Significance:

• Protects seafarers' health (preventing occupational noise-induced hearing loss) and improves safety (so that alarms, shouted warnings and orders can be heard).
• Promotes comfortable accommodation and privacy/rest, which prevents fatigue and improves performance and morale, in line with the MLC requirement for decent accommodation.
• Requires the shipowner to design/operate the vessel to achieve the limits and to measure/envelope performance; provides guidance on design, installation (silencers, resilient mounts, insulation) and on the operation (e.g. noise surveys, protection).

The primary noise level limits (Code, 2014; and previously the 1981 code) applicable for a ship at sea (new ships) include: accommodation spaces (cabins, mess rooms, recreation) not exceeding about 60 dB(A) (sleeping months 60, offices/work spaces 65), machinery spaces (engine room control room) working area typically 90 dB(A) maximum, with motor room and some work positions not exceeding 110-115 dB(A)? - The 1984 Code: accommodation 60 dB(A), galley 70, engine room control/workshop 75, machinery spaces 90, and an absolute maximum of 110-120 at work stations? The newer 2014 Code: noise not exceeding 110 dB(A) at any place on watch? I will give: accommodation spaces 60 dB(A), dining and recreation 65, work stations/in workshops 70-90 dB(A), machinery spaces 90 dB(A) except control rooms not above that, with a maximum of 110 dB(A) at the work station and ear protection above 85. It also set that no person should be regularly exposed to noise exceeding 80 dB(A) over 8 hours? - I will note the key figure: accommodation max 60 dB(A); engine room/machinery working spaces max 90 dB(A); control room max 75? and a peak not above 110-115; and that above 85 dB(A) hearing protection must be used. I will present representative limits carefully, noting they vary with the edition and the ship type; the essential point is that accommodation must be quiet (<=60 dB(A)) and machinery spaces limited (<=90 dB(A)) with hearing protection and quieter design.

Note: The Noise Code covers ships of 1,600 GT and above engaged in international voyages; it is amended, refreshed (2014) and there is a "Code on noise levels" which provides limits for ship types (passenger/cargo) and spaces.

Noise Survey Report: A document (required by the Code, and MLC-related) that records the measurement of the noise levels at the stated work stations, accommodation and other spaces on board a ship, taken after the ship is built or has significant noise-relevant modifications. Its purpose is to verify that the ship meets the required noise limits. Contents: the measuring equipment used, the survey locations and points, the measured dB(A) values, sea conditions/ship load, the date/position, whether the ship complies, and sign-offs by the competent/approved surveyor. It supports the "noise compliance" data kept onboard and is used to establish whether noise mitigation is needed.

Noise Attenuation Plan: A document that identifies the measures to be taken to reduce noise where levels exceed the limit or could cause harm - i.e., an engineering/organisational plan to attenuate noise (e.g., fitting silencers, resilient mountings, acoustic insulation of accommodation, enclosing noisy machinery, using quieter equipment, and personal hearing protection). Contents: the identified exceedances, the proposed engineering and administrative measures, responsibilities, and implementation schedule.

Role during inspections/audits: The Noise Survey Report provides objective evidence that the ship meets the statutory/MLC noise requirements; the Noise Attenuation Plan demonstrates the approach to correcting any non-compliance. Port State Control officers and flag/RO auditors check that the survey report is on board and valid, that the ship's accommodation and work spaces are within the limits, that any attenuation plan is being implemented, and that hearing protection is provided where needed; this protects crew health and prevents the ship being fined/detained for noise deficiencies and supports the MLC compliance.