A COMPARISON OF TONAL NOISE REGULATIONS IN AUSTRALIA

Tonal noise, or tonality, as a component of environmental noise can be an important factor in the annoyance of people listening to that noise. Environmental noise with audible tonal components generally results in higher levels of annoyance than broadband noise at a similar level. To reflect this, specific assessment methodologies are applied to tonal noise in environmental noise regulations around Australia as well as internationally. Typically these assessment methodologies seek to determine whether a peak in a frequency spectrum exceeds a criterion level and, if so, what penalty should be added to the measured noise level such that it better reflects the likely annoyance.
While tonal regulations are in place throughout Australia, there is a significant variance in the level of tonality at which they require a penalty to be applied. The differences can be particularly significant for tonal frequencies lower than 200 Hz. In many cases, the level at which a penalty applies does not accurately reflect the findings of dose response studies into tonal noise. Additionally, the standard application of a flat 5 dB penalty in many cases, regardless of the amount by which the tonal component exceeds the criterion, makes the regulations relatively inflexible. This paper reviews tonal noise criteria applied throughout Australia and compares them to each other as well as to international criteria and the findings of dose response studies to tonal sources. The tonal assessment criteria are used to assess examples of tonal noise from some sources to review the difference in outcome between the regulations.