The case of the open-air opera festival causing noise problems was well publicised in the national press. In this article, Ken Ratcliffe (ISVR), Dr Ray Shack (ADS) and Stephen Turner (Stanger Science & Environment), the consultants involved, tell the story.
Introduction
Garsington is a village five miles southeast of the centre of Oxford. Since 1989 Mr & Mrs Ingrams, the owners of Garsington Manor have organised performances of opera on summer evenings ('the Opera Festivals'). The operas are performed in the courtyard which, it was found, had excellent acoustic qualities for the purpose; staging and seating, for an audience of about 400, being brought in each year for these events.
The number of performances has increased over the years. Complaints about noise only commenced after the1993 season in which there had been an increase in the number of events to fifteen performances and three dress rehearsals held over a period of about a month starting from about the second week in June.
The operas usually commence at 6.00 p.m. with an interval of about 90 minutes to allow the patrons to picnic in the gardens or have dinner in the great barn. The performances end at about 10.00 p.m. The music is unamplified and over the years the festival has built up a good reputation, achieving critical acclaim.
The Problem
The sound from the opera mainly affects those who live along the nearby road, Southend, the closest property, Home Close, being some 70m to the rear of the stage. The opera is clearly audible in the large front and side garden of this property with the singing and the brass instruments being particularly dominant. The situation is exacerbated on fine still evenings, but on less clement days the intrusion is far less.
Following the complaints in 1993, the opera company commissioned Dr Ray Shack of Acoustic Design Services to carry out a series of noise measurements at a number of locations including Home Close, during the 1994 season, Ms Monica Waud, the owner of Home Close, commissioned noise measurements to be made at her property that year, and measurements were also carried out by Mr David Saffin of South Oxfordshire District Council. Following the 1994 season, Mr Ingrams was prosecuted by the SODC for causing 'unreasonable disturbance'
The prosecution was upheld in the Magistrates Court but overturned on appeal. No limits had been set by SODC, but Ms Waud's advisers suggested, as a guide, the use of the Noise Council's Code of Practice on the Environmental Noise Control at Concerts and stated that in their view a music noise level (MNL) exceeding the LA90 by about 5 dB(A) must be considered unsatisfactory.
In addition to the evidence from those affected by the opera noise, evidence was heard from local residents in favour of the opera festival. In the end the appeal was won on the problem of converting what are effectively planning issues into a criminal offence. The judge considered the note in para. 3.3 of the Code of Practice: The nature of music events means that these guidelines are best used in the setting of limits prior to the event to be 'peculiarly apt'. The judge could not see the effect of the increase in the number of performances that had previously occurred and concluded that it was difficult to see anyone convicted of a criminal offence when his own conduct has been a mere repetition (in 1994) of that which had been regarded as lawful and formally unobjectionable in the previous year (in 1993).
1995
SODC granted temporary planning permission for 12 months in January 1995 allowing an increase to twenty performances plus three dress rehearsals but subject to the following noise condition:
No opera performance shall take place until sound attenuation measures have been implemented in accordance with a scheme which shall first have been submitted to and approved in writing with the Local Planning Authority. The scheme shall be submitted within two months from the date of this permission. The measures shall be retained for the duration of the opera festival and shall be designed to achieve a level not exceeding 2 dB(A) above the background level where the background level is the L90 level measured over a one hour period at the same time of day as the opera but when no performance (practice or other opera related activities) is taking place, and the measured level is the average of any 3 five-minute Leq levels taken whilst the opera is being performed measured 1 metre from the façade of any dwelling.
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Garsington Manor with the screens under erection.
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The noise attenuation measures included heavy acoustic curtains with supporting structures designed by Ray Shack. During that season, SODC commissioned Stephen Turner of Stanger Science & Environment to assist them. His report stated that there was a noise problem to be addressed, particularly at Home Close, but that the options for noise control were limited. Unlike pop concerts, there was no means of controlling the noise as it occurred through an amplification system as none existed. Furthermore, measuring the Music Noise Level was not easy given the variable nature of the source superimposed on a variable residual noise environment, which, at times, produced LAeq levels well above the MNL.
1996
A planning appeal was heard before an inspector in April 1996 in connection with the conditions attached to the permission granted for the 1995 opera season and, in particular, the noise condition. Noise evidence was prepared by Mr Saffin and Mr Turner for SODC, and by Ken Ratcliffe of ISVR Consultancy Services who had been commissioned by the Opera Company. The consultants agreed that with no specific guidance available the Noise Council Code should be used as a basis for assessment. With the number of events being 23 in the year, it was agreed that the criterion should be MNL = Background + 10 dB(A), lying roughly half way between 12 events (permitting Background – 15 in Table 1 in the code) and 30 events (permitting Background + 5 in Note 5 to Table 1 of the Code, albeit for indoor venues). It was also agreed that the guidance given in Note 4 to Table 1 of the Noise Council Code applied. This states that: For those venues where more than three events per calendar year are expected, the frequency and scheduling of the events will affect the level of disturbance. In particular, additional disturbance can arise if events occur on more than three consecutive days without a reduction in permitted MNL.
As the 23 events occurred over a period of a little more than one month, it was agreed that the criterion should reduce to MNL = Background + 5.
Stephen Turner further argued that in his view much of the disturbance arose from the variable nature of the opera noise. Such variation is not taken into account in the Noise Council Code which is primarily concerned with amplified music which has a much smaller dynamic range. Consequently, he argued that there was justification to reduce the criterion to a zero increase.
The Consultants also agreed that for the purposes of this assessment the maximum MNL of Home Close was 42.5 dB(A) but there was no agreement over the background noise level (the average LA90 over the four hour period of the performance) to use. The Opera company, based on previous limited measurements by SODC, said 37.5 dB(A), whereas SODC, following subsequent measurements, said that it averaged 35 dB(A) but could be as low as 31 – 32 dB(A). Using the Background + 5 dB(A) criterion, the Opera Company figures showed compliance, whereas SODC showed an excess, with on some nights that excess being as much as 10 – 11 dB(A).
Mitigation
The Inspector adjourned the hearing so that he could witness the 1996 season for which a further temporary planning permission had been granted. The Opera Company were aware that the attenuation measures needed to be improved from the 1995 season and the acoustic screening was extended and suspended on ?yacht? masts complete with winch mechanisms for raising and lowering the curtains. The detailed implementation of the design involving the lacing of the curtains to ensure adequate overlaps was found to be crucial. Strong winds tended to open gaps unless the lacing was carried out exactly according to the design.
In addition to further measurements of the opera noise being made during that season, tests were made of the barrier effectiveness and attenuation of 3 – 6 dB(A) was achieved at Home Close.
During the 1996 season the Opera Company sought planning permission for a seven year period. This was required primarily to enable the Company to plan ahead more effectively rather than relying on the assumption that the annual temporary consent would be granted. Consequently, when the Planning Inquiry reconvened in October that year it was to hear the case for the longer term planning permission.
The Inspector again heard evidence from a wide range of people including local residents supporting and opposing the event and some eminent people from the world of opera attesting to its artistic and cultural merit.
Inspector's Conclusions
In terms of the acoustic issues, the Inspector concluded:
The MNL at Home Close was agreed as a design target to be 42.5 dB(A),
The MNL should not exceed the background noise level by more than 5 dB(A),
There was no agreement over the background level since Garsington Opera assumed an average of 37.5 dB(A), whilst SODC assumed 35 dB(A), but possibly as low as 31 – 32 dB(A).
There may be occasions when the background noise at Home Close is indeed between 30 and 35 dB(A) but conversely, as he witnessed, there may be occasions when the noise from music and singing from the opera is so low as to be virtually inaudible,
Improvements to the acoustic screen would provide additional attenuation of between 1 and 2 dB(A),
The typical current MNL was about 40 dB(A),
The sound from the opera would be likely to be intrusive if a resident wished to sit quietly in the front garden of Home Close while an opera was being performed,
Passing vehicles and motorcycles usually drowned out the sound from the opera,
That intrusion from noise would occur from time to time in the nearest properties were permission to be granted,
Account must be taken of how frequently the noise would be generated and how disturbing it would be, and the enjoyment of the participants should be balanced against nuisance to other people.
The Inspector found for the Opera Company and the Secretary of State agreed with the decision in early 1997.
1997
It has already been mentioned that one of the major differences in terms of noise control between these events and usual pop concerts is that there is no control over the source noise level. The MNL heard at the receiver is dependent in part on the source level which for these events depends on the nature and the orchestration of the work being performed. Furthermore, even after the Inquiry there was still uncertainty over the actual value of the background noise level. Consequently, during 1997, SODC through Stanger Science and Environmental carried out a series of measurements to determine this issue.
Whilst the LA90 measurements were being made it became clear that the performances of an opera by Richard Struass seemed more intrusive than any previous opera. This was due to the orchestration which involved some intense brass passages. Consequently, measurements were made to determine the MNL due to the Strauss opera and whether or not the criterion of MNL = Background + 5 dB(A) was being exceeded on the nights it was performed.
The weather during that part of the summer was relatively inclement and only on two nights were SODC certain that an exceedance had occurred. The measurements also indicated that the MNL had risen to 44 dB(A) for some 15 minute periods during the performances. This was higher than the previously assumed design target upon which the Inspector had based in decision at the Planning Inquiry. Because of the lack of control that they had over the source level and hence there being no certainty that such problems would not persist, SODC issued a Summons on the opera company, alleging that noise such as to cause an unreasonable disturbance to persons in the neighbourhood had been caused on two nights. The case was heard in the Magistrates Court at the beginning of 1998.
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View towards the auditorium area from Home Close. Screening not yet in place.
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Magistrates Hearing
SODC called four local residents to give evidence on their behalf followed by two environmental health officers and finally two of their consultants from Stanger Science and Environment, Stephen Turner and Jane Evans. The Opera Company called three local residents to give evidence on their behalf, followed by Mr Ingrams and Ken Ratcliffe.
A demonstration of the sounds recorded by Stanger on an 01 dB's 'Symphonie' system was played to the Court. The intention was to give the Magistrates some indication of the relative sound of the opera compared to the other sounds within the noise environment. Although this form of support to evidence is unusual and can be questioned, no significant objection to its use was made by the Defendant. As agreed between both parties, it was made clear to the Magistrates that the sounds they would hear would not replicate the actual sounds as heard outdoors by the local objectors, but would provide an indication of what is heard.
The on-going problem of being able to measure directly the MNL arose again, and because the alleged levels had inevitably to be derived, the defence were able to query the validity. In general, because of the relatively inclement weather, the average background level that year was 37 dB(A), as had been previously asserted by the opera company. Consequently, the magistrate took the view what exceedance might have occurred was the result of the vagaries of the weather rather than by the actions of the opera company. Consequently, the case was dismissed.
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Screens erected.
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SODC subsequently took the view that they had done all they could. Ultimately, it was felt by some to be an unsatisfactory conclusion because for a few people in Garsington, the Opera festival does cause some disturbance and does intrude on the use of their gardens at a time of year when the hours of daylight are longest. Conversely, the absolute levels from the opera are not high, the opera does not really cause intrusion on dull days and the opera festival is over by mid-July.
Conclusion
This case raised a number of issues:
1. The benefit of the consultants for the various parties working together as far as possible was demonstrated. They met on more than one occasion and determined areas of agreement and disagreement. A document was produced for the inquiry setting out these matters. This seemed to be welcomed by the Inspector as it enabled him to focus on areas of dispute.
2. Simply because it was not possible to measure directly the level of intrusive noise did not mean that there was not a problem. Conversely, it is clear that it is not appropriate to set noise conditions in the form of limits which cannot be directly tested. Some other form of control is required (e.g. agreement over barriers, hours of operation etc).
3. The age-old problem of desiring to use a single figure LA90 to describe the background level when a fairly wide range actually occurs always presents difficulties. In this case, the Inspector/Magistrates were made fully aware of the variability and hence were able to make an informed judgement.
Ken Ratcliffe FIOA is at ISVR, University of Southampton, Dr Ray Shack FIOA is with Acoustic Design Services and Stephen Turner FIOA is with Stanger Science & Environment, ISVR and Stanger Science & Environment are members of the Association of Noise Consultants.
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