Was Stonehenege built for sound effects?

US researcher has come up with an intriguing new theory, claiming that the ancient stones were actually arranged to create a special sound effect. Steven Waller said the ordering of stones at the rock monument in Wiltshire could be an attempt to recreate a sound illusion known as an "interference pattern" during prehistoric pipe-playing rituals. The effect happens when two sounds clash, and results in some people hearing a louder noise and some a softer noise, depending on where they stand in relation to the source. People taking part in a ritual dance around a pair of pipers would have heard the music unexpectedly grow quieter as they moved past certain spots due to this natural phenomenon, Mr Waller said. This would have created the illusion that the sound was intermittently being muffled by invisible obstacles as the dancers circled the pipers, he said.