Of course, John, I doubt that "screams of the illegal migrants trapped inside" would compare with 10,000 watt elevated pole stacks 100-150 metres away and aimed directly horizontally at the wall ... matters of 'scaling' - since 'water doesn't scale' for film effects, I have my suspicions about sound transmission too ... :-)

What with the 'dispersion graph' of such stacks usually having the bulk of their energy at 90 degrees to the vertical face and all ...

Some locals have claimed that the inversion layer - town is sited at the top of the Great Dividing Range - helps channel the sound down Gowrie Creek miles away... The festival site is at the bottom of a large natural 'bowl' with ground sloping up all around it. Topology also cannot be ignored. This 5 metre high wall is not tall enough to affect any of that - and if it reflects the sound in its current location, it is likely to increase that sound path down Gowrie Greek.