New study suggests Stonehenge was designed to amplify voices within the structure

Thousands of years after it was built, Stonehenge still baffles many. Who constructed it? How was it erected and what for? While the answers remain a mystery, a new study at the University of Salford in Manchester gives us an insight into the acoustic properties of the wonder from circa 2200 BC.

Published in the Journal of Archaeological Science, the study suggests that the monument may have been designed to amplify sound.

Acoustic engineers at the university discovered this by constructing a 1:12 acoustic scale model, which determines how sound would have resonated or been altered by the structure's  original 157 stones.

Using laser scans of the site from the Historic England public body, the team from the university was able to recreate the precise dimensions and placement of the stone monoliths, including those that are no longer standing.

To ensure the accuracy of their findings, the researchers used stones created to match the acoustic properties of the monument’s actual materials.

When it came to testing the model, the team placed small speakers and microphones in and around it, with sounds played at 12 times their normal frequency to account for the differences in scale.

Findings reveal that sounds created within the circular structure could be heard clearly by those inside, but the same sounds would be muted to those on the outside. Meanwhile sounds from the outside would not have been easily heard by those within the "henge enclosure".

“Although it is not known what sort of rituals, ceremonies or activities took place at Stonehenge in the Neolithic period, nor whether these included the playing of musical instruments or speech, the results suggest that any sounds created within the stone circle were best 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,” the study states.

Today, the Stonehenge site in Wiltshire, England, has about 63 complete stones, plus an outer circle of 17 sarsen stones. In July, researchers claimed to have been able to detect where the prehistoric monument's largest stones came from. The study in the journal Science Advances states that Stonehenge's builders hauled most of the slabs, which weigh more than 20 tonnes, from a woodland area in Wiltshire.