An Australian framework of environmental noise objectives has been developed, by the
EPA to provide a basis for consistency, equity and effectiveness in the application of
noise control measures.
Noise Quality Objectives
1. Noise from any single source does no intrude greatly above the prevailing background
noise
2. The background noise level does not exceed the level appropriate for the particular
locality and land use.
For these purposes Noise Control measures to be applied to a source of potentially
offensive noise may be determined relative to the existing background noise levels at the
receptor. Alternatively, absolute levels may be set by the State EPA. In
either case, the background noise level appropriate to the predominant land use of the
area should be borne in mind.
Level of Intrusive Noise
Social surveys have indicated that noise from any particular source will be audible to
many people in the community when that noise exceeds the background level by more than
5dB(A). The noise may have characteristics which are pleasant or unpleasant to the
listener.
Thus, when considering the environmental consequence of noise from a specific source,
any increase above the background sound pressure level, which exceeds 5dB(A) may be
offensive. This increase is determined as the difference between the L10
value at the receptor with the intrusive noise occurring and the L90
value determined in its absence.
Acceptable Background Noise Level
Our perception of noise and its level of offensiveness depends greatly on the broader
situation within which it occurs. Noise which might intrude into a library, sleeping
place or Casula solitude, and so be found offensive, could pass unnoticed by a sports
crowd or in a market place. the concept of background +5dB(A) derives from this
consideration.
A general schedule of recommended background noise levels (assessed as L90
in dB(A) units) has been compiled from international, national and local experience
and is shown on the next page.
Acknowledgment: EPA (NSW) - Environmental
Noise Control Manual and Australian Standard 2107 - 1987 Recommended Design Sound Levels
