Noise in the environment is made up of a wide range of different frequencies. The human ear responds more to frequencies between 500 Hz and 8 kHz and is less sensitive to low frequency or very high frequency noises. To allow noise measurements to take account of the response of the human ear to differing frequencies, frequency weightings are used. For the measurement of noise associated with events at Parklands, two frequency weightings (A-weighted and C-weighted) are used.
The figure below provides a graphical representation of the differences between the frequency weightings. It can be seen that the C-weighting is much flatter with only limited attenuation at the low frequencies. This weighting provides a better measure of the control of low frequency 'bass' music from the event sound system.
Certain weather conditions may increase or decrease noise levels observed at a given receptor location during an event. This is because certain weather conditions can focus sound-wave propagation paths at a particular area. Of particular importance to the propagation of noise from the event sound system are temperature, wind (including speed and direction) and the presence of temperature inversions.
For example, where winds are blowing towards a given receptor location (i.e. source to receptor winds) noise levels at the downwind location can increase. Similarly, where winds are blowing away from a particular receptor, noise levels propagating from the event would be lower at upwind receptors. These weather effects typically increase/decrease noise levels by 5 to 10 dB.
A range of meteorological factors are considered before each event held at North Byron Parklands (Parklands) which then feed into the comprehensive noise mitigation measures that are put in place. Unpredictable weather patterns can affect the distribution of noise, which can carry some noise to the surrounding community, particularly wind speed and direction and temperature inversions. As a matter of course, such weather patterns will continue to be examined leading up to an event.
The Bureau of Meteorology (BoM) Climate Outlook for Winter 2017 which covers the period of Splendour in the Grass 2017 points to a drier than average outlook over the southern half of mainland Australia. Outlooks are being influenced by warmer than average tropical Pacific sea surface temperatures and a cooler than average eastern Indian Ocean. With a reasonably neutral El Nino/La Nina index, trade winds across Australia are generally weaker and somewhat unpredictable in terms of strength and dominant wind directions. What these predictions generated from various weather models mean for likely noise distribution around Parklands during Splendour 2017 is difficult to accurately determine. Residents are encouraged to review BoM and other weather prediction services generally some 3-4 days before the commencement of the event (20th of July 2017) to determine wind direction and wind speeds.
Parklands adopt best practice acoustic management techniques to minimise the potential acoustic amenity impacts on the surrounding community. This is achieved by incorporation of a range of design and management measures into each event held at the venue.
Best practice acoustic management techniques incorporated into the design of the event include:
Prior to commencement of the event, the implementation of the control measures are audited and signed off by the independent noise consultants. Where further modifications to the noise attenuation measures are identified by the noise consultants prior to the event, they are implemented subject to consultation with event organisers as necessary to ensure that the implications for the security and safety (of event staff, performers and patrons), emergency personnel access, fire and traffic have been effectively considered.
The management measures adopted by festivals held at Parklands to limit the potential for unacceptable noise impacts on nearby sensitive receptors include both proactive and reactive measures.
Proactive noise management measures adopted include:
In addition, meteorological data collected by the on-site monitoring station is reviewed throughout the event to determine the requirement for further specific acoustic controls to accommodate the influence of weather conditions on the propagation of noise from the event. You can access Parklands Weather Station data here
Also throughout events, reactive management of noise emissions is provided through the use of event trigger levels. The trigger levels provide feedback to acoustic monitoring personnel and event stage managers where noise levels are approaching the noise limits at sensitive receptors. Warnings are triggered when short-term noise levels, measured at the mixing desk, exceed the event levels established during sound checks (or varied throughout the event due to variations in meteorological conditions). At any time where the short-term trigger levels are exceeded, the event stage manager implements strategies to reduce noise levels.
In addition, where attended noise monitoring identifies that noise from the event is exceeding the noise criteria, the acoustic consultant:
-Reviews the meteorological data recorded by the on-site monitoring station.
-Reviews front of house noise levels to determine whether they are consistent with the levels established for the event.
-Resolves conflicts between the actual and recommended front of house levels. Where required, the event stage manager(s) is contacted and request that noise levels be reduced with monitoring continuing at the location until event noise levels have reduced.