Rudman's city: Smells have gone, but now the Civic is leaking sound

By BRIAN RUDMAN

The mysterious smells that haunted the revamped Civic Theatre when it reopened for business have long gone. But in their place are two more serious - and expensive - problems.

One is the oversprung floor in the stalls which councillor Kay McKelvie says bounced "like a mini-trampoline" when her more energetic neighbours joined in the action at the recent Buddy Holly show.

The other is the failure of the sound-proofing between the main auditorium and the Wintergarden entertainment complex underneath.

It is a problem which could cost $750,000 to fix. Who will pick up that tab is still a moot point since acousticians, designers, builders and council officials continue to puzzle over what has gone wrong.

Or more to the point, why it has gone wrong, because show patrons such as Peter Stephens, of Glen Eden, are only too aware what had gone wrong.

Mr Stephens was one of several irate patrons at last Saturday's performance of Mikado who would have happily marched hall management off to the Lord High Executioner for a dose of punishment to fit the crime - in this case strapping them ear-down atop a big bass woofer.

The Gilbert and Sullivan devotees were blasted out of the world of Tit Willow and Nanki-Poo by the steady throb of the bass-heavy dance band at the none too "private" function below.

Mr Stephens says Civic staff expressed surprise when he and others cornered them afterwards. They shouldn't have been. It is their job to manage a serious sound leakage problem that the city council and The Edge have aware of since March last year.

What is causing additional concern is the gut feeling that the problem is getting worse.

The council's Civic project manager, Terry Mansfield, ruefully recalls the euphoric mood in November 1999 when the $42 million theatre refit was christened with the controversial Louis Vuitton bash.

Towards the end of the evening the music in the Wintergarden - the main party room - was so loud you couldn't think or speak. Mr Mansfield, acoustics consultant Chris Day and project manager Malcolm Sabourin retreated upstairs into the auditorium, closed the doors and were greeted with blessed silence. They looked at each other and congratulated themselves on having done even better than planned.

Mr Mansfield says that subjectively, there's been nothing louder in the Wintergarden since. Yet noise leakage is now a growing problem. Unfortunately, no scientific readings were done around opening day. But now, in the low-frequency area that bass sounds inhabit, the acoustic shielding is up to 10 decibels below design specifications.

Tests have been done on door seals, the old brick walls and various cavities to try to find the culprit without real success. The investigations are now concentrating on the two slabs of concrete - both the thickness of an Auckland telephone book - suspended as acoustic baffles between the two performing venues.

The top one of these is sandwiched between steel beams below and the wooden framing above which supports the main auditorium stall seating (see graphic). More than 1000 holes have been punched in this top concrete layer through which run steel rods called hangers which support both the concrete slab below and below that, the plaster ceiling of the Wintergarden. The rods are isolated from contact with the concrete by rubber mountings. This is designed to prevent sound transfer.

The hypothesis is that something has gone wrong - either in the design or the installation - and the rods are, in some cases at least, making contact with the concrete. Preliminary tests seem to confirm this. The contact could be within the hole through which the rod runs in the top slab.

Sections of the stalls floor are to be lifted for further tests. If the diagnosis proves correct, the complete stalls floor area will have to be lifted and each hole drilled larger, a process taking at least two months.

In the meantime, The Edge management is supposed to have a damage-control system in place restricting the levels of sound travelling either way when the venues are simultaneously occupied.

On Saturday, Edge chief executive Greg Innes says, the system temporarily failed. He blames the band, which he says defied instructions to play softly until the Mikado was over.

The plugs were pulled on it after 10 minutes and upset Mikado patrons have been offered free tickets to tonight's show.

Meanwhile the vibrating floor - it has a bounce of 8mm - is, I'm assured, safe, even if Mrs McKelvie had visions of the collapsing Israeli reception centre in mind when it happened. However, because the problem is "causing a discomfort perception to patrons" - to use the wonderful jargon of the official report - $50,000 is to be spent on two vibration-deadening pillars which will run from the Wintergarden bar area through to the stalls floor above.

The experts promise they won't carry extraneous sound as well.