Noise Control at an All-night Event at Turweston Aerodrome. Robert Peirce MIOA & Kevin Garthwaite AMIOA.

Introduction Since the Noise Council produced recommendations that music from night-time events should not be audible within noise sensitive properties with windows open in a typical manner for ventilation (1) the majority of one-off night-time events have adopted an inaudibility criterion within the licence conditions. At an all-night music event at the Turweston Aerodrome near Brackley, the Local Authority adopted a noise criterion which stated that noise levels shall not exceed LAeq,10min 45 dB as measured at a distance of 1m from any noise sensitive dwelling. This article reviews the noise criteria for night-time music events in the light of the results of the Turweston event. The Turweston site prior to the event. Rational Behind Conditions Set at Turweston The noise condition of LAeq,10min 45 dB, as measured at the façade of any noise sensitive dwelling, was based on the guidelines provided in the 1980 World Health Organisation report (2) which recommends an internal sleep disturbance criterion of less than 35 dB LAeq to preserve the restorative process of sleep. However it should be noted that these guidelines have been superseded by the WHO Criteria Document on Community Noise, 1995 (3) which states that where noise is continuous, the equivalent noise level should not exceed 30 dB(A) indoors, if negative effects on sleep are to be avoided. The LAeq, 10min 45 dB condition was derived from the internal sleep disturbance level of 35 LAeq plus 10 dB attenuation from an open window (based on research by the BRE which indicates that an open window provides around 10 – 15 dB attenuation). The Local Authority also felt that it would be appropriate to set a low frequency limit of 70 dB in either of the 63 and 125 Hz octave frequency bands which was taken from the Noise Council's guidance notes (1). The LAeq, 10min 45 dB criterion was adopted by the Local Authority in favour of the inaudibility criterion as it was considered to present a fairer balance between noise disturbance of nearby communities and the enjoyment of the event for around ten thousand members of the audience. A criterion based on the prevention of sleep disturbance was considered appropriate for a one-off event rather than complete inaudibility within noise sensitive dwellings. A typical all-night dance event. Inaudibility The objective for the Local Authority at the Turweston event was to set a noise condition at which the event could be held successfully whilst still allowing local residents to enjoy a reasonable night's sleep. In setting the condition it was borne in mind that this was a one-off event and the Council would be unlikely to grant a licence for a similar event at this location more than once per year. The Local Authority asked itself the question, is inaudibility a reasonable condition? It was considered that the priority was to ensure that residents were able to sleep whilst accepting that most reasonable people would tolerate a small degree of noise for a one-off event. It was the view of the Local Authority that inaudibility also presents monitoring and enforcement problems. The EHO would have to visit every complainant and listen to the noise within properties which would take a great deal of time and might ultimately lead to delays in getting the noise reduced. The EHO would probably have difficulty in finding some of the properties in small rural villages with their unmarked lanes and tracks. Indeed the process of driving around quiet lanes and walking up and down long driveways to find properties, could cause a measure of disturbance in itself. The Local Authority also observed that inaudibility was not considered appropriate for inclusion by those who drafted the new Noise Act 1996 which takes an internally measured 35 dB(A) as an upper limit to intrusive neighbourhood noise. There is a view that inaudibility as a licence condition can encourage complaints from residents who may have fears about such an event which are unconnected with noise. As a result pressure might be put on an officer by some complainants to reduce noise levels below that which the officer would normally consider to be reasonable. Experience shows that a minority of local people who are strongly against such events (it is widely held that raves have a poor media image) may well seek to have an inaudibility criterion imposed by the Local Authority to register their feelings about the event rather that being genuinely disturbed by the noise. Finally, inaudibility is of course subjective, and this raises issues over enforcement. Clearly background noise levels in a dwelling create a problem as do personal variations in hearing acuity. The Turweston Event It is likely that most readers have little or no experience of all night raves. At this particular event there were 6 marquees, each with separate sound systems which ranged in power from 5 to 20 kW. Other significant noise sources at the site included a fairground and noise from the audience, especially when thousands of people used trumpets or horns simultaneously. It was observed that the noise from the marquees was dominated by low frequency rave music, often with the Master of Ceremonies ?shouting encouragement? over the music. Location This particular event was licensed between 1900 to 0700 hours on a Saturday night in August 1997 and it was the first time that this venue had been used to hold such an all-night music event. Turweston airfield is an ex-World War 2 airfield situated on the north west edge of rural Buckinghamshire and is currently used as a flying school. The nearest villages of Turweston and Whitfield in neighbouring Northamptonshire are located approximately 1.5 km and 1.25 km respectively from the event and can be considered as affluent rural villages, where experience suggests that noise complaints are likely. The nearest large town is Brackley which is located 2 km away. Measured Internal and External Noise Levels To keep the noise levels to within the LAeq,10min 45 dB criterion at the nearest properties the internal noise levels within each marquee were generally controlled to a level of between 96 to 98 dB(A). Further control was also required to reduce the impact of both the speech component and the low frequency component of the noise throughout the night. If noise levels were found to increase at the nearest properties then immediate reductions were implemented in the marquees. Depending on external observations, either the overall noise levels (a blanked reduction for each marquee) or individual noise sources (when these could be identified) were reduced. This enabled the LAeq,10min 45 dB noise condition to be met throughout the night. At 0500 the noise levels rose at the nearest village by approximately 5 dB(A) and temperature inversion effects were thought to have been partly responsible for this; accordingly the music noise levels in the marquees were reduced to between 90 – 93 dB(A) at that time. The weather conditions on the night of the event were warm and calm with no significant wind component, a fact that assisted in the control of the noise. Noise Complaints The council set up a telephone hotline at their control centre at the event and this was widely publicised through the local parish councils and in the media. On the night a total of 19 households phoned to make complaints about noise from the event which began at 1900 and ran through until 0700 the following morning. Between 1900 and 0030 only one complaint was received from a property in Whitfield where the noise level had risen to about 48 dB(A). The level was reduced to around 43 dB(A) and the complainant telephoned back to say that he was satisfied with the reduced level. No further complaints were received until 0030 when in the space of one 45 minute period about 15 complaints were received from the Turweston/Brackley area. The Local Authority measured levels of about 50 dB(A) at Turweston village and the complaints ceased after the music noise levels were reduced to below 45 dB(A). Three additional complaints were received at other times but the assessment of the patrolling officers was that of 'over sensitivity by the complainant'. At one of these locations a façade level of 34 dB(A) was measured and at another the officers could not make a valid measurement above the level of traffic noise on a nearby main road. On talking to these residents it became evident that their objections to the event were not wholly noise-related and included light pollution from the fun fair rides and a concern for local wildlife. At around 0400 a complaint was received from Whitfield and the façade levels were found to have risen to around 48 dB(A) which was taken to have derived principally from a change in atmospheric conditions. Throughout the event there appeared to be a correlation between the level of complaints and the short periods when 45 dB(A) was temporarily exceeded. Conclusions The wider consensus among the officers and consultants involved was that the environmental noise levels were controlled successfully at the all-night dance event at Turweston Aerodrome through the use of an objective noise criterion in the licence conditions rather than inaudibility. The onset of noise complaints closely matches transgressions of the LAeq,10min 45 dB noise condition which indicates that an absolute noise level can be used to effectively control the noise from all-night dance/music events. It seems quite likely that the imposition of an inaudibility criterion at Turweston would have prevented an otherwise successful all-night event from taking place. Bibliography (1) Code of Practice on Environmental Noise Control at Concerts, The Noise Council, (1995). (2) Environmental Health Criteria 12, Noise, WHO, (1980). (3) Criteria Document on Community Noise, WHO, (1995). Robert Peirce MIOA is a Senior Consultant with Symonds Travers Morgan and Kevin Garthwaite AMIOA is an Environmental Health Officer with Aylesbury Vale District Council.