Brüel & Kjær Sound & Vibration Measurement A/S

Case Study: Glastonbury Festival - Noise Monitoring At Glastonbury Festival

In 1970, an entrance fee of just 1.00 would have permitted you, and about another 1500 'free spirits' to enjoy a weekend of listening to the likes of Quintessence, Marc Bolan and T-Rex, while at the same time savouring the undoubted 'delights' of free raw milk!!

Almost three decades later, and at slightly greater expense, you and over 100,000 other people can now enjoy the delights and unique atmosphere of Europe's premier outdoor music event with over 250 acts performing on ten stages, as well as many other attractions ranging from cabaret, theatre, comedy and circus, to numerous children's activities. This is Glastonbury Festival, millennium style.

Glastonbury Festival is mainly recognised for its formidable line-up of contemporary, and often less contemporary bands which in 1999 included REM, The Manic Street Preachers, Blondie, Fat Boy Slim and the Chemical Brothers, and in 2000 included David Bowie, Moby, Travis, The Pet Shop Boys and Ocean Colour Scene. There are nevertheless many, many more attractions contained within this seven hundred acre green field site bounded by over five miles of double-layer security fencing, complete with watch towers! For those interested in logistics, other mind-boggling statistics include the presence of some 800 traders on site, over 1900 toilets and approximately 10 miles of pipework supplying mains water across the site.

Since 1970 Mendip District Council has had the, some would say, unenviable 'privilege' of both licensing and monitoring this unique public entertainment event. This process alone, which involves the drafting and monitoring of almost 200 Conditions, requires not only careful planning over a period of in excess of six months or more, but also the use of in excess of eighty staff, many of whom are recruited from outside the Mendip Council area.

Noise is but one of many aspects that the Council must seek to control by way of Conditions, (with currently 15 specific Conditions attached). However, it is undoubtedly one of the few areas which, if it all goes wrong, has the potential for causing the greatest disturbance to nearby village residents.

The question for the Council therefore is, how do you effectively control noise from ten open-air stages, countless additional attractions and some 800 market traders, many of whom have their own sound systems with combined sound power outputs of in excess of 30KW? Not to mention the general noise associated with the permitted 100,500 festival goers!!

Many years ago, long before the Noise Council's Code of Practice on Outdoor Music Events was even in its embryonic stages, the Festival was limited to an off-site noise Condition of 60dBLAeq (15 min.) measured at a nearby residential property. This Condition was specifically designed to control noise from the then 'Pyramid Stage' which was unfortunately destroyed in a fire shortly before the 1994 festival. The renamed Main Stage which replaced it was used for 5 festival events, then for the Millennium a new Pyramid Stage was constructed a phoenix rising from the ashes!

The logic, or even the 'hunch', behind the 60dBA limit has unfortunately been lost in the annals of time. However, the level has been found, over a long succession of events, to correlate very well with a basic 'no nuisance' criterion and therefore continues to be the yardstick on which the off-site Noise Conditions continue to be based.

As the event has grown, and consequently the number of stages from one to ten, there has been a need to expand the number of locations at which the 60dBA limit is applied in order to control noise from all sources. Whilst this has been achieved with little difficulty in practice, the reality of subsequently monitoring such a limit, at what is now four off-site locations over a period of three days, where the line-up of bands on each stage is such that music is almost continual between 10.00 a.m and 12.30 p.m. daily (midnight finish on Sunday), is somewhat more challenging.

The process of control therefore involves the deployment, both on-site and off-site, of teams of officers equipped with often temperamental radios, with the specific task of ensuring that off-site levels are not exceeded. This requires the on-site teams to establish a level (LAeq(1min)) at the mixer positions (or 'front of house') which correlates with non-exceedance of the off-site limit. Continual dialogue between the on- and off-site teams over the duration of the event thereafter should ensure satisfactory compliance.

However, this task becomes considerably more onerous when one considers that not only must the on-site teams negotiate the huge crowds moving around the site; but also, the off-site team, equipped with a suitable four-wheel drive vehicle, must similarly negotiate off-site congestion and confusing one way systems, the combination of which means that circumnavigating the site alone can typically take over an hour.

In the context of this it is perhaps not surprising that the monitoring of noise during the millennium event involved some 25 officers employed over 70 shifts.

For many years, the off-site noise monitoring locations have been equipped with Continuous Noise Analyzers programmed to monitor a range of statistical parameters averaged over fifteen minute periods. Whilst this has been generally acceptable, there are clear disadvantages to this method of monitoring, insomuch as they:

- require regular officer attendance in order to adequately monitor the event
- are not real-time measurements
- do not benefit from the capability to carry out real-time frequency analyses

In an attempt to overcome these problems, and to generally improve the efficiency and effectiveness of noise control, the Council liaised closely with Brüel & Kjær who had kindly offered to allow the Council to conduct a trial of a developing remote noise monitoring system, for the 1999 festival.

The system consisted of an outdoor microphone feeding acoustic and calibration signals to a 2260B Investigator linked to a GSM mobile telephone. A laptop computer running 7820 Evaluator software completed the system and was located at the temporary Environmental Health office positioned within the Festival site itself.

Real-time noise analyzer, 2260B Investigator, was set to measure and store a vast range of noise parameters, including 1/3-octave frequency analyses, at five minute intervals during the sound tests, and at 15 minute intervals at all other times.

In this way, the current and past results were available at any time by requesting Evaluator to call the monitoring station and download its latest measurements. This procedure resulted in many practical benefits to the Environmental Health Teams, including;

-instant access to results, without the need for often difficult and time-consuming journeys to remote monitoring locations
-the ability to give an immediate response to the Sound Engineer's requests to increase the volume!!! Indeed, where necessary, changes could be monitored immediately at the appropriate location and quick decisions made identification of extraneous noise within the ambient noise profile by referring to simultaneous frequency analyses
-the ability to interrogate the stored information during the post-event period, and during quiet periods of the Festival!!
-it was a completely independent noise monitoring system requiring no challenging connections, other than the site office land line telephones. It should however be noted that a strong GSM network signal is required, and that this is very much area dependent. Experience has indicated that for the Festival site, a fruity and orangey coloured GSM network supplier would appear to be the preferred option!!

Without doubt, the trialled remote noise monitoring system proved to be highly successful in permitting considerably more effective and efficient control of noise from the Main Stage. It permitted not only a quick assessment of complaints, but also facilitated a quick response to the Sound Engineers inevitable requests for increased amplification!!

Looking ahead, the potential for such a system is considerable, both at Glastonbury Festival and also for other applications. In particular, the following are highlighted as potential developments and/or uses:

- general-purpose short- to medium-term automatic monitoring of any noise-sensitive event (e.g., music festivals, pubs and clubs, motor sports, water sports etc.). Indeed it is likely that it will soon be used to monitor a new Noise Abatement Zone remember them?
- monitoring and control of low-frequency noise for music festivals immediate effects can be observed from the remote station and mixers adjusted accordingly
- recording of the audio signal at the remote station for subsequent replay or analysis
noise source location investigations by observing the (remote) effects of switching on and off potential sources in turn, or comparing frequency spectra

The introduction of relatively low-cost remote noise monitoring using general-purpose noise measuring instrumentation has opened up a whole new way of controlling environmental noise. These same techniques have already been used to help minimise the effects on Mendip District Council's residents in 1999, and again in 2000. In the future it is highly likely that remote noise monitoring of this kind will become a permanent part of the folklore of Glastonbury Festival events in the years to come.

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