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RCA Research Team Uncovers Stonehenge's Sonic Secrets

For years archaeologists have been mystified as to why giant 'Preseli' bluestones from Mynydd Y Preseli in Pembrokshire, south-west Wales ended up at Stonehenge, almost 200 miles away. But now researchers from the Royal College of Art think they may have found the answer, along with a surprising new role for Britain's most popular heritage site: the bluestones may have been sought for their unique acoustic properties, which together made up a prehistoric soundscape at Stonehenge. The findings have been published today in the Journal of Time & Mind, and come at a timely moment with the opening of the new Stonehenge Visitor Centre later this month (18 December).

The College's Landscape & Perception Project (L&P) is a pilot study into the 'raw' visual and acoustic elements of the Pembrokeshire landscape, on and around the Carn Menyn ridge, on Mynydd Preseli, south-west Wales – the area where many of the famous Stonehenge bluestones originated. 

Sound specialist Jon Wozencroft, Senior Tutor in Visual Communication at the RCA and the author, photographer and 'archeo-acoustic' expert Paul Devereux have been leading the project, working with a diverse team spanning archeology, neurology, aerospace engineering, music and percussion from institutions including Bournemouth University, Bristol University, English Heritage, the University of Wales and Princeton University. 

The study was conceived in order to demonstrate to design students how direct sensory material for their digital work can be used – tasking them to look and listen as if with Stone Age eyes and ears. In the process, the investigators uncovered the remarkable fact that the source area of the Stonehenge bluestones is a natural soundscape, and that sound might be a much more significant factor in our understanding of Stonehenge and prehistory generally.

Sonic rocks

Sonic or musical rocks are referred to as 'ringing rocks' or 'lithophones'. A significant percentage of the rocks on Carn Menyn produce metallic sounds like bells, gongs or tin drums when struck with small hammerstones. Where suspected Neolithic quarries are located, there’s an even higher localised percentage. 

The Preseli village Maenclochog, which itself means bell or ringing stones, used bluestones as church bells until the eighteenth century. While the Preseli area has long known of lithophones, the L&P project has confirmed why so many Neolithic monuments exist in the region, and provided strong evidence that the sounds made the landscape sacred to Stone Age people. The study quantifies the comments of the British archeologist and early 'rock gong' pioneer, Bernard Fagg, who suspected there were ringing rocks on or around Preseli, and suggested the link between these and the sacredness of Neolithic monuments and landscapes. 

In July, English Heritage gave the L&P investigators unprecedented permission to acoustically test the bluestones at Stonehenge. Accompanied by archaeologists from Bournemouth and Bristol universities, the research team set to work testing the megaliths.

They didn’t expect much, as lithophones require ‘resonant space’ – space, in which, sound waves have sufficient room to vibrate to produce the pure sounds that can be experienced on Carn Menyn. The bluestones at Stonehenge are set deep into the ground (some having been supported in concrete), which can also dampen acoustic potential.  

To the researchers’ surprise, however, having tested all the bluestones at the monument, several were found to make distinctive (if muted) sounds. This was a sure indication they would have been fully lithophonic if they'd had sufficient resonant space. Furthermore, a number of bluestones at Stonehenge show evidence of having been struck. This have been in order to create an acoustic environment, according to Wozencroft. A full understanding of the nature of these markings will require further archaeological investigations, however.

Magical stones 

The L&P team believes the bluestones came from a mysterious soundscape, imbued with special magic and sanctity in the eyes of the megalith builders. This may have been the prime reason behind the otherwise inexplicable transport of these stones nearly 200 miles from Preseli to Salisbury Plain. There were plentiful local rocks from which Stonehenge could have been built, yet the bluestones were clearly considered special.

Today, lithophones are considered as mere curiosities, but it’s a mistake to project modern prejudices on to prehistory. We know from cross-cultural studies that in much of the ancient world echoes from rocks, cliffs or inside caves, or rocks that made musical or unusual sounds when struck, were thought to contain spirits or magical forces. Lithophones, in particular, were held in high regard. The architects of Stonehenge may well have held similar beliefs.