Ear traffic control

By Deborah Diaz

The worst that could happen would be an operatic version of air-guitar. Dead air and 20,000 ears at North Harbour Stadium waiting to hear something. It would be something like Aida without the spectacle, and La Traviata's soundmen will not let it happen.

They are scientists in black t-shirts. They understand that opera depends on architecture and the laws of physics. There is the shape of the throat and mouth. There are acoustics. Every note, whether it leaves the lips or a speaker, travels at roughly 305 metres a second.

Inside a stadium, soundmen can turn down the volume of the orchestra by dropping it into a pit. The domed ceilings of concert halls allow sound to bounce up to the cheap seats of the gods.

Outside at North Harbour, the human voice cannot climb above the orchestra to the stand's crest. You need microphones, amplifiers, kilometres of cable and 2000 watts.

This is not opera at its purest but for the soundmen who will control every note in the stadium on February 25, opera outdoors is a particular artform.

"The stands are the best place to be, not the stage," says Paul Jeffery of Oceania Audio.

"That was a fundamental problem we faced outdoors on a set of this scale. The performers themselves are standing in very confused sound."

Imagine it. The soprano sings a note, then hears it as it comes over the speaker. It travels into the stands and bounces back in a fraction of a second — "hello, hello, hello".

Oceania, headed by Jeffery and Greg Peacocke faced that problem when they tackled Carmen last year. The company has been around since the 1970s and now has 30 employees and an office in Australia. They did Auckland's Big Day Out, This is It, Kiri at Gisborne and so many millennium events "we all got a few more grey hairs".

Putting opera outdoors is one of the biggest challenges they have faced. To let 10,000 punters hear one concert in a stadium, sound designer Simon Venning has had to create virtual worlds of sound. To get performers out of the confusion, they seal them off.

Each of the 11 principal singers has a flesh-coloured, Madonna-style microphone under their wigs and costumes connected by wires to a radio transmitter worn on a belt. Their voices are collected by the soundmen, who add it to the mix the audience hears.

For safety — "you cannot lose a principal" — each singer wears two mics and transmitters. The soundmen can switch between the two channels during the concert, depending on which is delivering the best sound.

The principal singers hear only what the soundmen send to their earpieces by a radio receiver, again worn on the belt. Each performer can have an individual mix for each song.

The 26-strong chorus have their own frequencies, though not the luxury of a personalised soundtrack. Instead, they have to watch the conductor like a hawk for their cues on television monitors hidden in the set. Their back-up is a 20-strong chorus off-stage, which the soundmen can also ease in and out of the mix.

"From our point of view, it makes no difference where they are," says Jeffery. The orchestra, too, is wired-in from a room inside the stadium, pumped out via 50-odd mics and cable.

Stage management staff are on walkie talkies, taking up another two frequencies, and light and sound operators have a separate communications system.

This is a lot of traffic — more than 100 radio frequencies for parts of one opera.

"That's why they ask people to turn off their cellphones. The phones are constantly searching for an open cell, and if they pick up on one of the frequencies you get errrrrrr-chhhh! Arrr-eeeech! Cccssshhhhh," says Jeffery.

Ear traffic control is perched high in the stands. Each is about the size of a double bed, has about 2000 knobs and is worth $130,000. Surprisingly, they can be driven by only seven or eight technicians during the event, though it takes more than a week to set up.

Jeffery says fine-tuning is done on the hoof.

"It's so expensive to get everything and everyone together that there is very limited run-through. We have 30 minutes to balance the orchestra. You don't get a second go at it."

This is just what soundmen do. Science and contingency plans stand between them and dead air.

But electrons can't be controlled entirely by knobs, as was proved last year during Carmen when the taffeta costumes created static electricity that put crackle over the air.

"Nature wound up working in our favour. The moist night-air came in and dampened things down."

Just miking up can be an art. Each person's chemical make-up, moods and sweat can affect the radio waves.

"On the day, it can come down to experience and intuition."


• La Traviata, North Shore Stadium, February 25.