Festivals — Managing off-site noise

Posted on / 19 Apr 2019

The news that a new festival is coming to your neck of the woods can be greeted with great enthusiasm (if you’re a festivalgoer), or great trepidation (if you aren’t)! This could even be for the same reason – pounding bass and screaming guitar solos running through until the wee small hours… The savvy festival production team knows that in order to keep their event permission for the next year, keeping the neighbours on-side is paramount. This could be as simple as some free tickets, or more complicated – a calibrated noise measurement system logging audio levels at front of house, with a volunteer steward performing perimeter measurements to make sure that things aren’t getting out of hand.

However, sometimes you might have an event in a noise-sensitive area. Perhaps there’s an antiques centre next door, or a roost of nesting seabirds around the corner. Maybe the people in the nearby houses just don’t like loud noises! Gaining permission to stage an event in such an area can be challenging, with reasonable (and sometimes unreasonable!) conditions being placed on the festival. These would typically take the form of decibel limits at a given position (or several), usually coupled with a ‘dead stop’ curfew for noise emission. There may also be some assurances required from the PA company, that the equipment they’re providing will send more acoustic energy into the audience than leaks out into the surrounding area.

We at Puxley Limited have something of an advantage over other companies providing similar sound reinforcement – because of our equipment choice and staff training, we’re able to deploy systems where almost all of the acoustic energy is focussed entirely onto the audience – meaning that comparatively little spill is heard off-site. However, sometimes it’s necessary to provide information on this dispersion to an official body. While we already have simulation software which can tell us exactly what a loudspeaker system is doing within the festival side (i.e, where the audience are), but working out what the levels will be at any point off-site has been nearly impossible to predict; it’s obviously not cost-effective to take an entire festival system out for one day to get some measurements before the event begins, and thus we have all been at an impasse.

Now though, there is another solution – NoizCalc. NoizCalc is a piece of acoustic simulation software designed for use with d&b audiotechnik loudspeaker systems, which lets you program in the location of your event, along with details of the sound system provided. It then performs some very clever mathematics, and presents at the end of this process a 2D top-down heatmap showing anticipated audio levels at any point in the area surrounding your event. This sounds more complicated than it is! Below is an example dispersion for a festival that we provide audio production services for at Abbotsbury Subtropical Gardens.

This is, at its core, a heatmap of audio levels – redder colours are louder, and bluer ones are quieter, as per the scale to the right. This map takes into account nearby forested areas, buildings, different types of terrain (grass, roads, dirt, etc), even the elevation of ground! This map has been calculated using the ISO 9613-2: 1996 measurement standard; in short, a ‘worst case’ scenario – on the day, it’s likely that things will be even more controlled than they are shown to be in the simulation. We can use different audio spectra to calculate this heatmap – obviously a folk music event will be quieter and sound different spectrally when compared to an outdoor thrash metal show!

Previously, while documents like this have been available, the cost associated with acquiring them has been considerable, requiring an acoustic consultant to take measurements of the festival surroundings, along with requiring detailed information on the noise sources present at the show. Now, we can create these detailed plots for you in-house, letting you put together a package which can ensure the continued running of your event.