The panel array acts as a baffle, quickly causing decay of the reverberation from excited children in Goulburn’s public pool

Determined to beat Nature’s law that says kids must out-yell each other in public swimming pools, Goulburn Mulwarree Council has used Pyrotek Soundguard’s soundproofing know-how to deal with the high noise level and reverberation in their aquatic centre.

Designed by Collingridge & Associates Architects and assigned to Pyrotek and its approved applicator, Gifcon, to implement, the solution was to hang acoustically absorptive panels from the ceiling of the pool hall in an array designed to literally “baffle” the noise.

“More accurately, the enemy is reverberation,” says Pyrotek’s Soundguard technical representative, Bruce Hermes. “The uniform sound field built up by noise bouncing from reflecting surfaces in an enclosed space decays only to the extent that sound energy is absorbed by those surfaces.

“The building’s interior surfaces bat noise back from one to the other like a ball between tennis players in a long rally, extending the reverb time intolerably. And reverberation at certain frequencies can be more than a nuisance; it can be a health hazard.”

It was this realisation that prompted the council to budget for capital works to address the problem and for the council’s facilities engineer, Andrew Galland to approach Sydney architect, Collingridge & Associates, whose investigations led to collaboration with Pyrotek Soundguard in the solution of the problem.

“We estimated a reverberation time of 6-7 seconds,” Bob Collingridge reports. “The frequency of the noise from overly excited children we put at 1-2 Hz, which is considered potentially harmful to human hearing.”

The architects proposed the use of panels suspended over the pool as a means of introducing into the space the additional surface area of sound-absorbing material needed to reduce reverberation time down to one second or less. It also had to be aesthetically acceptable.

The choice of material was made after consultations with Pyrotek Soundguard, who recommended their Sorbertex 3D P46W.

This comprises a core of very fine polyester filament with an acoustic membrane on both faces to absorb sound energy impacting from either side. It is light weight, so can be hung in the largest sheets available of 2400 by 1200 mm. It is plain but attractive in all white. Polyester is 100 per cent recyclable and is hypoallergenic. And it is unaffected by the moisture and chloride ions prevalent in the pool environment.

Architects and the council also relied on Pyrotek Soundguard and its installer, Gifcon, to come up with the method of suspending the specified 31 rows of panels hung three abreast above the pool on wires; also of dealing with some quite tricky aspects of the installation itself.

The pool was drained for the installation so that Gifcon could work off scaffolds. Unlike erecting scaffolding in an ordinary hall with a flat floor, the job here was complicated by the slopes of a pool’s bottom, requiring scaffolding to be taken down and rebuilt as the installation progressed up the length of the pool.

Reporting on the outcome, Andrew Galland says “There has been a notable improvement. We are happy with the result. Reverberation is far lower than before.”

Bob Collingridge’s verdict is: “The resulting improvement in aural comfort for those at work in the centre is considerable.”

And speaking for those who have daily experienced both the “before” and “after”, David Gustafson, the Centre’s supervisor, claims: “Before, when the pool was packed, we would have to shut our doors on the noise to hold a phone conversation. Now, it’s 100 per cent better.”