The Whispering Wall........shhh!

Last Saturday we went further north-east of Adelaide to see Gawler, which has been one of the earliest white settlements in the area. Well, it's not that old, just around a century and a half.

The interesting thing around the area was the Barossa reservoir, better known as "The whispering wall". On the outside it looks like just another dam with an arched shape, retaining water on one side and trees and shrubs on the other.

But the funny thing about it is, that when you stand close to the dam wall at one end of the reservoir, you can hear a person talking at the other end (that's about 150 meters afar), as if he's standing right next to you! Spooky!!

The secret is in the shape of the dam. The tall thin concrete dam curved against the pressure of the water had been radical at the time of construction over a 100 years ago and the parabola effect causes sound-waves to bounce so that people speaking at one end of the dam can be heard as if the person is standing beside you ! The wall is one sector of a perfect circle, and the sound-waves bounce in a series of straight jumps along it to the other end. Cool!!