Archaeoacoustics at Avebury

Archaeoacoustics is a fairly new branch of archaeology that studies the acoustic qualities of caves inhabited, or used ritually, during prehistory and ancient buildings such as the Newgrange tomb-shrine and Stonehenge. Studies sometimes include the use of instruments contemporary with the sites themselves.

I visited Avebury last weekend with my friends, Amanda and Pete, taking with me the newest of my Celtic lyres, wire strung and made from Oak. Towards the end of the day, we arrived at the huge southern entrance stone known in local folklore as ‘the Devil’s Chair’ due to a natural cleft, the base of which forms a comfortable seat in the southern face of the stone, the face that greets people arriving into the henge from the processional route along the West Kennett Avenue. At Amanda’s request, I broke my usual protocol against sitting in the seat so that she could photograph me with the lyre. It was then that we made a remarkable and surprising discovery.

Sitting in the notch in this enormous sarsen stone, I began to play the lyre. As I played, I moved the instrument across my lap until it was facing into a hollow depression in the stone beside my right thigh. I don't know what prompted me to do this, presumably the spirits of the place, but I noticed as I did so that the volume of the lyre increased dramatically when the soundhole was aligned with the hollow and pointing at it. The amount of amplification was quite startling. So much so that I decided to explore it further. Standing up, I held the lyre as far away from the stone as I could lean and still manage to play it, then, continuing to play, moved it towards the stone. From about a foot and a half in front of the stone’s face, the increase in volume was very marked indeed, maximum amplification being achieved when the soundboard of the lyre was almost inside the hollow ‘seat.’ Such was the acoustic feedback coming off the sarsen stone that the last note played on the lyre sustained for much longer than the instrument was normally capable of, continuing to ‘ring’ for several seconds. I didn't count, but I'd guess a good ten seconds longer than usual, probably more.

I thought the effect might be extremely localised and that you’d need to be right on top of the instrument, as I was, in order to appreciate it. Thanks to Amanda and Pete, I quickly learned that this was not the case. They were standing five or six yards away, between the sarsen and the busy main road that runs through the henge. When the lyre was facing away from the stone, any passing traffic drowned it out completely. When it was played facing into the stone, it was clearly audible, even over the sound of large lorries going by. We found that the effect varied depending on where you were standing in relation to the face of the stone, with particularly strong effects heard when standing at a shallow angle to it and at some distance to the side.

I tried calling into the ‘seat’ hollow and found the same effect, my voice being considerably amplified and thrown back at me. This led me to wonder if the effect might have been used to project sound towards the gap between the banks where the West Kennet Avenue reaches the henge. I would imagine that an instrument like a bull horn would have had considerable impact on anyone entering the henge at that point. The fact that the sound was being thrown from the entrance stone would have made its source hard to identify. I’ll have to try it on my next visit.

It’s amazing that I’ve been visiting Avebury for more than forty years, have taken part in ceremonies that have included the southern entrance stone for more than twenty years, but had never previously noticed this acoustic effect.

Pete made some recordings, and if they came out OK, I'll add them to this post.

Incidentally, I don't mean to suggest that an Iron Age lyre, played in Europe from at least 800 BCE, was contemporary with a Neolithic henge constructed between 2800 and 2200 BCE. Clearly it wasn't. The lyre just happened to be the only instrument I had with me. Next time, I'll take a bull horn and a clay drum...

Blessings of Caer Abiri,
Greywolf /|\