Aaron Watson Archaeology Research
Grey Cairns of Camster
The Grey Cairns of Camster are chambered cairns in Caithness, northern Scotland. Both have been excavated and restored. One of these monuments, Camster Round, was a good focus for acoustic research because it was mostly restored using original materials.
Camster Round is a stone-built passage and chamber buried within a large circular cairn, a format often described as a passage grave. This creates a dramatic juxtaposition between the inside and outside, emphasised by the claustrophobic passageway.
Sounds generated inside Camster Round are loud and enhanced because they are contained by the confined chamber. Sound does not travel easily along the passage, however, so a listener outside will only hear a very distorted impression. Higher frequencies are lost, enhancing sounds such as drumming.
Away from the passage entrance, higher frequency sounds become even more filtered. Around the back of the cairn, bass sounds created by drumming in the chamber sounded like they were emerging from beneath the ground rather than from inside the cairn.
Intriguingly, the sound of a drum within the chamber of Camster Round could be distantly heard from within the chambers of nearby Camster Long. These monuments are 200m apart, and the sound could not be detected in the open air between them.
One explanation is that these sounds were being transmitted through the ground, or that the comparative silence in the chambers made it possible to hear sounds that were otherwise obscured by natural noises in the outside world.
Standing waves at Camster Round
The enclosed chamber of Camster Round was ideal for standing waves, resonances created by the interaction between sound waves as they reflect between the walls. Standing waves were easy to make, requiring a constant tone from either the voice or musical instruments. By varying the pitch it is possible to ‘tune’ into the space. At Camster Round there are a variety of standing wave resonances, some rather more distinct than others.
When a standing wave was generated the sound appeared to develop a life of its own, expanding to fill the space and behaving in extraordinary ways. This included unexpected changes in volume as the listener moved around, and even subtle shifts in pitch. The sound even behaved in counterintuitive ways. It could become quieter nearer to the source, or suddenly appearing to change completely in nature. Standing waves could also distort the voice in unusual ways, as well as resonating with parts of the body to create uncomfortable and unnerving sensations.
Interpreting the acoustics of Camster Round
Camster Round can create a variety of theatrical sound experiences. The filtering of sound between the inside and outside of the cairn creates contrasting experiences between those people inside the chamber and those outside. Whatever events were taking place there, it is only possible for a small group to share the confined chamber. This could suggest that some people were excluded entirely or participated at different times.
An audience outside could not have seen what was taking place in the chamber, and the sounds that they heard would have been highly distorted. Perhaps they were understood as an expression of the power of the monument to transform both place and people. Standing waves might have been understood as the voices of spirits, ancestors or other forces. They might have contributed to the special character of the monument as these sounds could not have been reproduced anywhere else.
Passage grave often contain substantial evidence for the deposition of the remains of the dead, but this does not mean that they were tombs. Rather than a final resting place, perhaps a structure such as Camster Round was part of an elaborate sequence of rituals. Perhaps this was a place where people could engage directly with forces or dimensions beyond the everyday, the extraordinary sounds accompanying journeys by both the living and the dead.