by Kay Leather
Stonehenge and Stonehenge Aotearoa
Stonehenge Aotearoa is not a replica of Stonehenge England. Their sizes are slightly different, they have a different number of pillars, the pillars are not evenly spaced and the height of the henge is different from its English counterpart. Ours has an obelisk just off-centre and there are no bluestones. The pillars are hollow and their exterior has concrete spray texture. However, the sounds observed by many visitors and performers at Stonehenge Aotearoa suggests that their acoustics have much in common. Many of the statements made by R. Till in connection with Stonehenge England also have relevance to Stonehenge Aotearoa, though the sound at Stonehenge Aotearoa is yet to be scientifically measured.
“In attempting to understand the acoustics of a monument, whether it be an enclosed or open space, we may consider two factors: the physical laws of acoustics, and the human perception, or ‘aural experience’ of the monument. Acoustic principles are constant, unchanging with time; human perception is quite the opposite!
So there are several types of measures to be investigated, which can be divided in two main groups related to hearing and listening. The first group holds the quantitative (hearing) measures. Some measures are based on physical laws, while others are related to the combination of the ear and brain (psychoacoustics).
Measures based on physical laws are, for instance, sound pressure level, clarity, reverberation time and early decay time (Bradley 2011, 715; Cross and Watson 2006, 109-11).
As experiences in monuments cannot always be explained by physical laws, a more subjective explanation can be provided by including psychoacoustics. Examples of these psychoacoustic measures are perceived loudness rather than sound pressure level, and timbre – the character of a sound rather than its frequency and intensity (Cross and Watson 2006, 111- 13).
The second group holds more qualitative (listening) aspects which depend mainly on the cultural environment of the listener by considering, for instance, semantics and aesthetics (Schafer 1977, 146-50; Storr 1933, Chapter I). This is concerning the mind.”– Reijs & Mussik
“Let us consider the most obvious paths of sound in a circular stone building. If standing in the middle of an open field, when one makes a sound it leaves you and keeps traveling away, thus there is no reverberation. If one stands in a rectangular building and makes a sound, it leaves you, hits various walls at different times, and reflects back to you at different times, creating reverberation as the echoes created merge together. If standing at the centre of a circular building, when one makes a sound it leaves you, hits and reflects straight back from the wall at all points of the circumference simultaneously, and these reflections return to you at the same time. In a large enough space this would produce a prominent echo and reverberation from the combination of a number of ‘echoes’, or reflections. If standing at the edge of a circular space, when one makes a sound it will leave you, reflect back off the wall directly opposite and return as a slightly later echo; travel to one side reflect off the wall twice making a triangular shape and return a little later still; hit a wall three times making a square shape and return a little later; hit five walls forming a pentangle and return a little later; and so on. The overall effect would be echoes (in a large space) or resonance/reverberation (in a smaller space where the differences in distance are small and so the sounds are not distinguishable). In circular stone spaces the size of Stonehenge… there would actually be both reverberation and echoes…
Stonehenge could be made to resonate further by producing sound in time with the echoes in the space. One could make Stonehenge resonate, much like blowing over the top of a bottle to make it hoot, or like running one’s finger around the top of a glass; or hitting the skin of a drum. This would work by making the air in the space vibrate at its fundamental resonant frequency. Measurements of the diameter of Stonehenge told us that this frequency would be about 10Hz. Stonehenge is of course not a simple circle, it is a complex monument involving a number of geometric shapes. However despite this, theoretically it should still have a strong fundamental resonance at this frequency. The circle of stone lintels placed on the outer ring of upright sarsen stones protrudes largely above any other stones, and would provide an almost unheeded clear ring of stone, and any resonant effects could be supported by the upright stones that support the ring of lintels.
That the fundamental resonant frequency of Stonehenge was 10Hz raised a number of interesting questions. Different types of brain waves that are present during various different mental states have specific typical dominant frequency ranges. 10Hz is a frequency that when detected in the brain is described as an alpha wave pattern. As alpha waves are often associated with relaxation, altered states of consciousness, meditation.
Clarity and definition in the space were found to be slightly lower than ideal, while level and envelopment were higher. These figures indicate the space was better for music than for speech. It also indicates that the acoustics would support rhythmic music better than sustained musical sounds. The acoustics also act to engage those within the stone circle and exclude those outside. The strong envelopment would be ideal for activities in which a high level of engagement and participation was required, rather than where some people present were able to remain detached from the activities…
Evidence has been found that low frequency modal resonance and standing waves could indeed have been generated at the site, perhaps by large numbers of participants playing small hand percussion instruments such as clay or wooden drums, or pieces of wood or stones. It also seems likely that these low frequency resonances could be produced by strong winds. This study revealed that there was a hierarchy of position in the space, implying that the different circles around the centre, such as the large bank and various stone circles, demarcated different levels of significance, with the centre the most important position. Being within the sarsen stone ring’s circumference would have produced a powerful sense of inclusion and involvement. The stones outside the central circle seem to have had significant acoustic effects associated with them, which would have linked them in perceptually to the main circle.”— R. Till
The acoustics of Stonehenge Aotearoa have not been scientifically tested but the builders and many visitors have noticed remarkable acoustic effects at Stonehenge Aoteroa.
Before we commenced the construction I had come across a summary of Dr Rupert Till’s investigation of Stonehenge, England but had forgotten exactly who was involved. However, we were curious to see if similar sound effects would be observed as we built Stonehenge Aotearoa.
Stonehenge Aotearoa is situated in the Wairarapa countryside:
- Latitude: 41 degrees, 06 minutes, 0,48 seconds, South
- Longitude: 175 degrees, 34 minutes, 24 seconds, East
- 94m above mean sea level
It has a wonderful view across the valley toward the distant hills.
It was designed to be an accurate outdoor observatory and a teaching tool for teaching both ancient and modern astronomy. It is 30m in diameter with 24 pillars, topped with lintels.
The main causeway is through the Sungate toward the centre of the henge. The causeway is aligned to the equinox sunrise.
The centre of the henge has a tiled square with a brass plaque at the centre. The hole in the centre of the plaque marks the exact centre of the henge. This point is where astronomical observations should be made. From this point the causeway, flanked by the Sungate marks the position of the equinox sunrise.
There is an obelisk just off-centre. The obelisk is at the head of a pictorial zodiacal analemma. The obelisk casts a shadow which falls on the analemma and traces the path of the sun through the stars of the zodiac. The analemma stretches from the obelisk to the outer circle of pillars. The centre of the analemma is aligned exactly north/south. Along the same alignment but beyond the circle of stones is the statue of Artemis. She marks the most southerly position of the moon.
There are six heelstones outside the circle of stones. They mark the position of the rising and setting sun at the solstices and equinoxes as viewed from the centre of the henge.
When building the henge, the first task was to exactly mark the centre of the henge. From that time on, the centre of the henge was a protected position.
The site itself was slightly sloping east-west, requiring some shaping on the east and building up for the heelstone on the western equinox position. The causeway approaches the henge from the East.
When the first six or so pillars were erected, with their lintels, there were strong sound effects. The pillars appeared to be reflecting sound toward the central position. This was very noticeable when people were talking to each other or when hammering. It became even more effective as more pillars were erected.
The construction of the obelisk was begun before the henge circle was completed and because it is taller than the lintels of the henge it offered a good viewpoint. It did not pay to make careless comment anywhere in the henge. A quiet comment made while working on the upper part of the obelisk or a lintel was very clearly heard elsewhere in the henge, almost as if the speaker was standing right next to the listener. We had a lot of fun with that effect.
When the construction of the circle was complete the effects were even more pronounced. The centre of the henge became the prime focal point. It seemed as if anyone speaking at the centre could be heard easily without raising their voice. Sound that was uninterrupted and continuous like singing rounders or clapping seemed to build on itself.
Away from the centre a time delay could be observed, especially obvious with clapping or other sharp sounds. People placed in different parts of the henge heard the same event at different times. Later, when the henge hosted full moon drumming events this was especially noticeable. Experienced drummers spent some time moving back and forth, in and out from the centre altering the timing of their drumbeat in an effort to put other experienced drummers off their beat. Inexperienced drummers often moved away from the central position only to find that doing so made it harder for them to keep time. Noticing this one night, I put a man, with a very large drum right at the centre. That soon cured the problem as the sound waves seemed to move the air in your lungs and it was impossible not to stay in time.
Another effect is the way the henge itself reflects sound. We have had some large musical events at the henge. At several, the stage was not in the centre of the henge, but outside the circle with its back almost touching the Artemis statue. The sound control tent was in the middle of the field on the eastern side of the henge, some 50m or more away.
When setting up the sound, the sound controller would call instructions to his workers in and around the stage. Every command was echoed back perfectly by the henge. I wondered how they would get on during the performance but it they must have controlled the echoes as it did not cause a problem.
When the large stage was set up, the large speakers were just next to the stage, facing away from the henge. During the set up, the sound was so loud that I found it uncomfortable at the house full paddock distant. However, the quietest place was at the centre of the henge. Here it was possible to have a conversation without difficulty.
I have often been amused by mothers located a 100m away from the henge, near the Visitors’ centre but with a clear line of sight to henge, who call their children who are still in the henge area. The henge amplifies their voice, and they looked so shocked at the noise they have made. Quite often they cover their mouths and look around to see if anyone noticed.
When mustering sheep we have also noticed that in some places what is said in the henge can be easily heard over 100m away. I have heard my husband talking to workers at the henge from the gate to the property. I was probably 200m from where he was. The strange thing is that if you move even a little bit, it is not possible to hear anything from the henge.
One of the first big events we had after the opening, was a Druid event. During this ceremony, the Druids march in a circle within the circle of stones, chanting their Arwen chant. At this ceremony the TV crew came to photograph the Druids.
The first thing we noticed, after the chant began, was all the birds in the area for some distance, flying into the air. This is unusual in New Zealand and we do not have the sort of mass migrations that happen in Europe.
The next thing that occurred, was that all animals that were, at that time, down the hill came racing up to the fence around the henge. A bull in the herd started bellowing, and was answered by another in an adjoining property. An old horse that came with the cattle started to behave as it was training in the Spanish Riding School. It pranced up and down, lifting is hooves as if to music, head held high and tail swishing. It was quite a sight. The TV camera operators did not seem to know what to photograph – Druids or animals. I was late arriving, due to processing late arrivals, and I just enjoyed the entire spectacle.
We encourage everyone who visits the henge to experiment and enjoy the sound effects in the henge and universally they are surprised at the effects they obtain there. Henges are fun places really. I am sure our ancestors used them to great dramatic effect.
Songs of the Stones: An Investigation into the Acoustic Culture of Stonehenge Dr. Rupert Till University of Huddersfield, UK.