The Whispering Wall of the Barossa Reservoir and Its Amazing Parabola Sound Effect

When the Whispering Wall was built over a 100 years ago, no one had a clue about its amazing acoustic properties. The concrete dam was constructed by about 400 workers over the South Parra River in Barossa Valley between 1899 and 1902. The dam holds back the 4,515-mega liter Barossa reservoir that supplies water to several areas in southern Australia. The Whispering Wall has always been famous – the 9 storey structure was the first arch dam to be constructed in the region and at one point, the highest in all of Australia. But little did the builders know about the hidden properties of the engineering marvel they had created.

Because the dam is a hard and curved surface, any sound made on one end travels completely unobstructed to the other end. So you could have a perfectly normal conversation with someone standing on the opposite end of the dam (about 450 ft. away), as though they were right next to you! The voices can be heard quite clearly due to a phenomenon known as the parabola effect. The wall is so perfectly curved that it forms one sector of a circle. And the sound waves just bounce in a series of straight jumps all the way to the other end.


Photo: Scott Davis

The dam’s whispering abilities were actually discovered by accident. According to locals, the story goes that during construction, a group of workers who were complaining about their boss were overheard on the other side of the dam. The Whispering Wall was revealed! Unfortunately, this wasn’t a cool enough discovery to save the workers’ jobs.


If you ever happen to travel to Australia, the Whispering Wall is one location you don’t want to miss. The place attracts a massive number of tourists each year, eager to test the wall for themselves. Some of them have even put up their ‘whispering’ videos on YouTube. The entire area is protected for native species, so the picturesque location is ideal for a picnic. The surrounding lands are covered in original scrub growth of pink gums and native pine trees. And thanks to all the trees, this is a great spot to do some serious bird watching.


Here’s another interesting fact about the Whispering Wall – the water in the reservoir is sourced from a weir over the river, through a tunnel over two kilometers away. The path was cut by a single horse – it took the beast nine months and he never got to see the light of day while working.