AS 1055:2018 pdf free.Acoustics—Description and measurement of environmental noise.
6.2 Measurement positions
6.2.1 General
The choice of the actual measurement positions depends on the purpose of the measurements, as specified in other parts of this Standard, or in other applicable Standards or as specified by the relevant regulatory authority.
The microphone shall be oriented so that it is most uniformly sensitive to the incident sound of the subject source (if there is one).
6.2.2 Outdoor ineasurenients
Where it is desired to minimize the influence of reflections, outdoor measurements shall, whenever possible, be carried out at least 3.5 m from any reflecting structure other than the ground. The preferred measurement height is 1.2 rn to 1.5 m above the ground.
6.2.3 Outdoor iizeasii rem en Is near buildings
Outdoor measurements near a building shall be carried out at places where the noise to which the building is exposed is of interest. Except when determining LA9O.T, an adjustment may be necessary where an approximation of the free field incident level is required. See Note 3.
NOTES:
1 The measurement positions should be I m from the facade and 1.2 m to 1.5 m above each floor level of interest. An adjustment may be necessary where an approximation of the free field incident level is required to account for the influence of facade reflections (see Note 2). Where measurements are made at different levels of a multi-storey building such as an apartment block, the location should be I m from the facade of the building separating the external area from the interior area.
2 Where measurements are made near a building the importance of certain transmission paths (for example, transmission through open or closed doors and windows) should be considered.
3 If measurements are performed I rn from the facade of a building and the sound is directly incident on that facade, an approximation of the free-field incident level may be obtained by subtracting 2.5 dB from the measured value. To characterize the effects of the walls of a building to be erected, the addition of 2.5 dB to the free-field values may be useful in order to estimate the sound pressure level near the walls. If measurements are made in the plane of the facade, subtracting 6 dB from the measured value to approximate the free-field sound level.
4 Measurements may be performed in the plane of a facade or roof of a structure utilizing a microphone whose protection grid or diaphragm is flush with the surface. Alternative techniques using pressure zone microphones placed against the relevant surface may be used.
6.2.4 Measurements inside buildings
Measurements inside buildings shall be carried out in those locations at which the noise is of interest.
NOTES:
I The measurement positions should be at least I m from the walls or other major reflecting surfaces, 1.2 m to 1.5 m above the floor, and about 1.5 in from windows. For general measurements within a room, at least three discrete locations should be used, evenly distributed in areas of the room where the sound level is required, unless the separation distance is less than I m.AS 1055 pdf download.