Stone age circles may have been 'amplifiers' for trances

Getting stoned at a music festival 5,000 years ago may have been more of a primitive experience than it is today but every bit as effective.

Scientists researching ancient circles of standing stones around Britain have formed the theory that they may have been built as hi-tech sound studios that helped to induce an altered state of consciousness among the crowds gathered to hear Neolithic humans' early attempts at rock'n'roll.

Researchers from Reading University discovered that many of the ancient monuments acted as amplifiers which, with the right frequency, could induce a trance-like state among devotees attending early spiritual festivals. The theory came about after Dr Aaron Watson, an archaeologist, discovered an increase in noise levels while examining a circle of 13 standing stones at Easter Aquhorthies, west of Aberdeen.

Dr Watson said: "When I first visited the circle, what struck me was, as I moved across the very central region of the monument, I heard an increase in volume – it became a fuller sound." After reporting his discovery to a colleague, Dr David Keating of Reading's cybernetics department, the scientists found the central recumbent stone amplified sound up to three times above normal.

The Easter Aquhorthies is a well-preserved and impressive circle of stones, graded in size, almost 20 metres (70ft) in diameter. The biggest stones are closest to a large granite recumbent stone and its flankers, which are located at the south-south-west of the circle. The flanking stones are more than two metres tall and the recumbent is nearly four metres long and carefully sculpted.

In the past seven years Dr Watson and Dr Keating have experimented at sites across Britain, including Stonehenge. An experiment at Maes Howe, a 5,000-year-old tomb in Orkney, found the chamber resonated sounds at 2hz – well below the 20hz normal level of hearing.