In the first modelling of Stonehenge of its kind, the University of Salford’s Acoustics Research Centre constructed and tested a 1:12 acoustic scale model of the monument, to determine how sound would have been altered by all of the original 157 stones in 2200 BC. With rituals usually involving sound, an understanding of the acoustics at prehistoric Stonehenge can help inform our archaeological understanding of the site and its possible uses.
Results from the study quantified how reflections from the stones enhanced musical sounds and speech, making projecting the voice easier. The results suggest that any sounds created within the stone circle were intended for others within the same relatively intimate setting, rather than to be broadcast more widely to those outside, whose view into the stone circle would also have been obscured. This evidence once again emphasises the contradiction between the large numbers of people required to transport the stones and construct the monument, with the small number of people able or allowed to fully take part in, and witness, activities within the stone circle.
Professor Trevor Cox, University of Salford, who is leading the project commented, “Constructing and testing the model was very time consuming, a labour of love, but it has given the most accurate insight into the prehistoric acoustics to date. With so many stones missing or displaced, the modern acoustic of Stonehenge is very different to that in prehistory.”
The acoustic scale model was based on a CAD model from Historic England. This used the Stonehenge laser scan data from Historic England and the latest archaeological research to create the shape and position of the stones. The academics constructed the acoustic models by using a mixture of 3D printing and specialised moulding.
Physical scale models are a tried and tested technique for designing concert halls, this is the first time it has been applied to a prehistoric stone circle. In order to model the sound correctly, the test frequencies are required to be 12 times larger meaning the sounds produced are within the ultrasonic region. The evaluation of the measurements then followed the latest techniques from architectural acoustics.
Stonehenge was reconfigured a number of times in prehistory and the scale model was made like ‘Stonehenge LEGO’ so different arrangements could be tested. The measurements showed that the introduction and rearrangements of the bluestones made subtle changes to the acoustics, which would have been inaudible in prehistory. Moreover, no echoes were audible in the 2,200 BC model. Overall, it seems improbable that sound was a primary driver in the arrangement of the stones at Stonehenge. Other considerations were more likely to be important, including the astronomical alignments, the incorporation of two different groups of stones, the replication of similar timber monuments and the creation of an impressive and awe-inspiring architectural structure.
Susan Greaney, Senior Properties Historian for English Heritage, who contributed to the project said, “Testing the acoustics of a scale model of Stonehenge has given some new insights into how the monument might have been used in prehistory. The results show that music, voices or percussion sounds made at the monument could only really be heard by those standing within the stone circle, suggesting that any rituals that took place there were intimate events. It’s exciting to see how modern techniques of laser scanning, 3D printing and acoustic modelling can tell us about the distant past.”
The results will be published in the October volume of The Journal of Archaeological Science. To view the paper click here.