See this BBC website article and slide show to read and hear about ‘virtual acoustic modelling’ which enables researchers to recreate the acoustics of the past. As they say in the excerpt, since Stonehenge was originally circular, it would have had a resonance which would eventually start to ‘ring’.
The article starts: Visitors to Stonehenge in Wiltshire rarely experience the historic site without the rumble of traffic noise from the nearby A303. But UK researchers have managed to recreate the sound of a ritual there, as heard by our ancestors 4,000 years ago.
The research starts in an echo-free recording chamber and uses latest computer modelling techniques. Read more.