Assessment Point

Noise levels shall be determined by carrying out measurements at the assessment point. Where a measurement is to be carried out at a building, the assessment point shall normally be at a position 1 m from the exterior of the building facade but may be at any other point considered to be appropriate by the Authority. Where a measurement is to be made of noise being received at a place other than a building, the assessment point shall be at a position 1.2 m above the ground, at a particular point considered appropriate by the Authority.

Where the noise under investigation is transmitted to the NSR primarily either through the structural elements of the building; through openings other than those at the facade of the building; or through specially provided glazing at the facade of the building as considers appropriate for reducing the noise, the assessment point shall be at a particular internal location which the Authority considers appropriate having regard to the normal occupancy of the building.

Noise Units and Descriptors

Any noise measurement to determine the MNL shall be made in terms of the A-weighted equivalent continuous sound pressure level (Leq) measured with an integrating sound level meter. Such measurement shall be made over any 30 minute period or any shorter period when the Authority is satisfied that the noise under investigation is essentially steady over a 30 minute period, which shall be taken to be the STP.

Rounding of Noise Levels

With the exception of the CNL which should be calculated to the nearest whole dB(A), with values of 0.5 or more being rounded upwards, other measured or calculated noise levels shall be determined to the nearest 0.1 dB(A) or dB, with values of 0.05 or more being rounded upwards.

Weather Conditions

Noise measurements should be made in accordance with international acoustical standards and practices in relation to weather conditions.