The echo of Stonehenge

The site of Stonehenge, dating from the 3rd-2nd millennia BC. J.-C., has only about sixty of the 157 original megaliths. • LIST

What was Stonehenge, the largest prehistoric structure in Europe, used for? Why did humans raise these circles of giant megaliths in southern England 4,500 years ago? The question will have exhausted generations of researchers and given rise to hundreds of hypotheses. A latest study has just established that the famous site has amazing acoustic properties:it amplifies sounds.

By reconstructing a model, British acousticians from the University of Salford discovered that, when the monument was complete (it originally had 157 stones, of which only around 60 remain today), not only the sounds that were emitted inside were amplified, but, above all, they could not be heard from the outside!

Stonehenge consists of two kinds of stones:the smaller, blue stones, arranged inside the first circle, come from Wales, and the larger, blocks of sandstone called sarsen stones weigh an average of 20 tons . After four centuries of debate, we know since this summer the origin of these megaliths, which is located in the wood of West Woods, 25 km north of the site.

Outdoor concert

The scientists therefore reconstructed the original site with the missing stones in the form of a 1/12 scale model. Using data obtained by laser scanning and 3D, they installed microphones and speakers, then emitted sounds at different frequencies. They found that the sound was amplified by 10-20% inside the structure – an effect similar to a room when the site is open air!

However, the researchers do not conclude that Stonehenge was designed solely for its acoustic properties. They are a characteristic linked to the ritual function of the site. But it is unlikely that prehistoric people deliberately designed the monument to achieve this effect.