The consultants of Vanguardia, which specialises in acoustics, sound system design and noise control consultancy, have been involved in the prestige project since its inception. The team, headed by Jim Griffiths, was brought in by owners AEG Worldwide to ensure The 02 would set a new world standard for stadium acoustics.
The team's task was threefold - completely acoustically insulating The 02 to minimise any noise spill into the environment, specifying an internal acoustic design to control reverberation time (RT) to a remarkable two seconds in the mid frequencies, and specifying the installed sound system for the main arena and provide advice for the smaller club-type venue within the complex.
The new systems were put to the test on 30 May when rental company ML Executives flew a full line array PA system at the stage end of the arena. The Vanguardia team carried out extensive acoustic measurements which confirmed the primary goals of sub-two second RT and minimal external noise spill.
Jim Griffiths says: "AEG were absolutely clear from the outset that the 02 would be designed first and foremost as a live music venue, and wanted the best acoustics of any large sized arena bar none. It was also essential to contain noise spill to ensure their events be granted licences without encountering objections.
"My first decision was to design the arena to be fairly acoustically dead, with a consistent reverb time right across the audio spectrum. That meant particular attention to low frequencies, which are always more problematic to contain than mid to higher frequencies. The RT increases slightly at low frequencies and reduces slightly at the high frequencies which provides an optimum acoustic environment. From the measurements we've been taking it's looking good and very close to the optimum situation."
After extensive acoustic modelling, all large areas of interior surface from the roof to the walls were acoustically treated, the biggest single measures being a heavyweight acoustic roof liner which reduces RT from 125Hz upwards, sound absorbing panels on reflective surfaces ñ including the backs of VIP boxes ñ and a series of bass traps around the perimeter to contain 40-80Hz frequencies.
"Because of the mass you need for effective sound insulation of the low frequency bass, a feature of modern music," says Griffiths, "our consultants predicted the roof would require 65kg per sq.m to achieve the necessary level of low frequency reduction, instead of the more standard 35-40kg, and that's what they went with. I worked closely with the structural engineers and roofing contractors to ensure the weight loadings were correctly distributed. Because it's fully acoustically absorptive, it's more like playing out in the open air, with minimal reflections - great for both musicians and audiences."
Vanguardia's Mark Murphy comments: "I was heavily involved with the project and designed the internal acoustics with the diffused sound field in mind - making sure there is good clarity for every seat, and we had input on the seat design itself to minimise reflections."
Griffiths adds, "The arena will work acoustically in any stage configuration; the usual stage position would either be at the south end - where the loading bays are - or in the round. We also considered the implications of having an open, 360-degree stage at one end, like a U2 stage, so people can look at the stage from behind. For sporting events, the full 360 degree bowl can be used with the benefit of the dine and view restaurant."
Vanguardia also provided advice for the venue's other audio system installed in the 3000 capacity In
