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Acoustic trick at scenic lookout leaves us baffled

Published on

George Mathewson

We’ve answered some unusual reader questions in ‘What’s Up With That?’ this year.

On this one, however, we failed.

The water plant operated by the Lambton Area Water Supply System features a circular observation deck on a hill overlooking Lake Huron where it enters the St. Clair River.

In the centre of this amphitheatre, which is popular with ship-watchers and skateboarders, is a knee-high circle of cemented stone. And if a person stands on this dais and speaks, a strange thing happens.

Your voice will sound as though it’s being electronically amplified, producing a weird, reverberating echo.

So what’s up with that?

The phenomenon is some kind of acoustical trick. But who designed it, and for what purpose?

Susan MacFarlane is manager of the LAWSS water plant.

She said photographs suggest the observation deck was built around the same time as the plant, in 1973.

But she had no explanation for the sonic enigma, although she was aware of it.

‘They say that if you stand in the middle of the lookout and speak you can hear an echo, but I’ve actually never done it,” she said.

“But, now, I have to go try it,” she added with a laugh.

Dillon Consulting Limited designed the water plant for the Ontario government, its original operator.

Harry Grund is a semi-retired Dillon project manager who knows the plant well and is currently working on its waterline-twinning project.

“It’s the first time I’ve heard of it,” he said from London.

“I don’t recall (the lookout) being part of the original plant design and it may have been an add-on by another consultant.”

After referencing Google Earth, Grund said the sound feature was probably built into the amphitheatre.

“I’m no acoustical engineer,” he said. ““But it seems to me the way it’s laid out, given the harmonics of sound, that the buildings themselves would allow that to happen. It’s probably not a coincidence.”

People familiar with the sound trick have their own ideas. Some believe it’s caused by sound bouncing off the curved walls. Others say the echo has something to do with the fact the lookout sits atop a giant underground water reservoir.

Susan DesJardine tried it out herself recently after walking her dog Thomas up the hill.

“That’s very cool,” the Sarnia woman said. “I have to tell others about it now and bring my girlfriends up here. And my husband. He’s a smart guy and he’ll figure it out.”

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