Acoustic Investigations

The Landscape & Perception project was virtually the first to investigate acoustics on Preseli, its main study landscape, but it is not the first to do so at Avebury where there has already been some sporadic acoustic research. In July 2007, Sarah May, senior archaeologist with English Heritage, and colleagues conducted an acoustic experiment in which replicas of ancient musical instruments were sounded from the summit of Silbury Hill in order to see how far the sound would carry, so as to explore what might have been involved if there had been such ceremonial use of the mound. May reported that one of the results of her sound mapping of the landscape around Silbury Hill was that one of the animal horn instruments they used could be heard as far as Swallowhead Spring, but not at all beyond it. It seems the “lie of the land”, the local topography, could “bottle” the sound. Further, Steve Marshall, one of the participants, located just to the north-west of Silbury Hill at the edge of the apparently deliberate flood plain or moat that surrounds the mound, heard distinct echoes from two locations on Waden Hill when the Celtic trumpet was played on Silbury’s summit. These were repeat echoes, very clear, lasting up to half a second in length. All the sounds produced “appeared to travel somehow over the top of the hill: musicians can be heard even when they are not visible.... This is not an effect of the wind,” Marshall states ( It is to be noted that a plane water surface enhances echoes, so there might have been even more marked effects if the experiment had been conducted during a wet period when the moat would have contained water, which was not the case during the experiment.

Because of this and other acoustic explorations by others at Avebury (some described later in this section), the fact that the complex was secondary to Preseli as far as the project’s focus was concerned, and the relatively limited resources available to what is after all a pilot project, the investigators have undertaken only very preliminary acoustic work there, and these are detailed in this section. A mapping of inter-site audibility within the complex is, however, planned for Spring 2012 and the results will be reported on this website in due course.

Devil's Den

Being the relatively best preserved dolmen within the general Avebury complex, the Devil’s Den was an obvious target for the investigators to check for lithophonic (“ringing rock”) properties. The monument was tested by percussion using small hammerstones, but no special acoustic effects were heard.

West Kennet Long Barrow

This monument is one of the earliest constructions within the Avebury complex. One of its reported acoustic aspects the investigators wanted to check related to an observation from a reliable source that the interior of the long barrow could collect sounds from unexpectedly large distances away in the surrounding landscape, like a giant stone ear or microphone. (This phenomenon has been noted by archaeologists in certain painted cave locations in southern California.) After a very preliminary test the investigators were unable to confirm this claim, but more exacting tests are required at a later date.

As the monument contains stone chambers and a passage, it is an ideal subject for testing acoustic resonances. On a visit to the barrow, the investigators conducted some preliminary tests, using balloon bursts as an inexpensive but workable impulse sound sources, authentic Australian Aboriginal ritual clicking sticks, and the human voice. Drumming was not tested at this time. There were noticeable resonances within the monument occasioned by these sound sources, but, again, more comprehensive and exacting tests are awaited.

No electronic testing instrumentation was used by the investigators for this preliminary exploration, but many months afterwards local musician and composer Steve Marshall, in touch with the investigators, conducted acoustic resonance explorations using his voice and an electronic keyboard as a tuning reference. In the first two eastern side chambers his bass voice produced a distinctive resonance so strong that it persisted for half a second or longer. The pitch was E2 (equivalent to the lowest open string of a guitar), and throughout the barrow he found a primary pitch of A2 – the 110 Hz resonance frequency already found in numerous Neolithic stone chambers elsewhere, and which seems to have distinctive regional brain effects on listeners – see the Archaeoacoustics page. Marshall has reported his full findings in the November 2011 (vol.4. no. 3) edition of Time & Mind – The Journal of Archaeology, Consciousness and Culture.

The Coves

There are the remains of two “coves” at Avebury – open box-like settings of stones in the northern inner stone circle in the henge itself and at the Longstones at the end of the Beckhampton Avenue to the west of the henge.

The Avebury Henge Cove. Even with one of its three stones missing, this open setting of megaliths produces powerful, resonant echoes as the investigators discovered during very preliminary percussive testing between the existing megaliths, and as had been noted years earlier by prehistorian Aubrey Burl during his studies at Avebury. A problem for full, precise acoustic study, though, is that nearby buildings also produce echoes which would make it technically difficult to isolate the ones specifically associated with the Cove, plus the fact that the missing megalith would need to be replaced by a dummy stone (such as a sheet of hardboard of appropriate size).

The Longstones Cove. Of the two Longstones, it is the massive “Adam” stone that is the survivor of the cove that once existed at this location. (The companion Longstone, “Eve”, is the sole standing survivor of the Beckhampton Avenue.) Excavations between 1999-2003 confirmed that there had been a setting of four megaliths, of which Adam is the only survivor, forming a cove structure. The positions of the other three stones were recorded. The 18th-century antiquarian, William Stukeley, had noted the presence of the Longstones Cove long before, when it was more evident.

In 2009, an experiment to mimic the possible acoustic characteristics of the Longstones Cove setting was conducted by Steve Allan, a lecturer in Music Systems Engineering at the University of the West of England (UWE), aided by Richard Pearson and Steve Marshall. Four hardboard sheets were erected at an open field site near the university to mimic the standing stones in their original positions. The main finding of the experiment was that the reconstructed arrangement of sound reflective surfaces acted somewhat like a megaphone. If this is indicative of the actual, original Longstone Cove, then the implication could be that cove settings were the locations where the Neolithic officiants conducted their oral or musical activities.

Devil’s Den: Percussion testing for acoustic properties.

Devil’s Den: Percussion in progress, testing for acoustic properties.

The eastern, entrance, end of West Kennet Long Barrow.

Inflating a balloon within the passage of West Kennet Long Barrow, but not for party time – the sound of a bursting balloon is a workable and inexpensive impulse sound source for testing environmental acoustics.

Testing the acoustics inside a side chamber within West Kennet Long Barrow, using authentic Australian Aboriginal ritual clicking sticks.

Testing vocalisation within West Kennet Long Barrow.

The two surviving stones of the Avebury henge Cove – the acoustically confounding proximity of buildings is evident. The megalith on the right in this picture is considered to be one of the largest standing in Britain.

The massive “Adam” megalith, sole survivor of the Longstones Cove.