New Scientist above.
Did our ancient ancestors build to please the ears as well as the eyes? Trevor Cox pitches into the controversial claims of acoustic archaeologists. And in our web-only article Acoustic archaeology: The secret sounds of StonehengeSpeakerMovie Camera, he explains how the acoustic footprint of the world's most famous prehistoric monument was measured
"The wind, playing upon the edifice, produced a booming tune, like the note of some gigantic one-stringed harp. No other sound came from it... Overhead something made the black sky blacker, which had the semblance of a vast architrave uniting the pillars horizontally. They entered carefully beneath and between; the surfaces echoed their soft rustle; but they seemed to be still out of doors..."
This atmospheric description of a "temple of the winds" comes from the dramatic climax of Thomas Hardy's novel Tess of the d'Urbervilles. The setting is Stonehenge, arguably the most famous prehistoric monument of all. Its imposing ring of standing stones is visible for miles on Salisbury plain in southern England. On the day of the summer solstice its outlying "Heelstone" is exactly in line with rays of the rising sun. A more perfect example of the visual impact of an ancient monument would be hard to find.
Might we be missing here something that both Hardy and our prehistoric ancestors understood? Some archaeologists have begun to think so. They argue that sound effects were an important, perhaps even decisive, factor in how early humans chose and built their dwellings and sacred places. Caves that sing, Mayan temples that chirp, burial mounds that hum: they all add up to evidence that the aural, and not just the visual, determined the building codes of the past. But is that sound science?
Assessing the claims of "acoustic archaeology" rapidly encounters a fundamental problem: sound is ephemeral. Pottery fragments, coins, bones and bits of buildings can survive for centuries, waiting to be analysed, interpreted- and reinterpreted. The sounds of the past, by contrast, have long since died away. Where historical records make mention of acoustic intent in designing structures, the claims are often based on faulty science (see "Sound design?"). Going back into prehistory, we do not even have the luxury of knowing what our ancestors were thinking- or often a clear idea of the original layout and acoustic properties of the structures we are interpreting.
There is, however, a plausible argument that sound must have been important to our ancestors, perhaps more so than it is to us now. "Today we guzzle sounds and make a lot of noise," says UK archaeologist Paul Devereux, an advocate of the claims of acoustic archaeology. "We are visually very sophisticated, but acoustically very primitive." Our ancestors, by contrast, would have been "acoustically more calm and attentive in a much quieter world", he says. Without artificial light, listening intently would have been imperative to ward off night-time predators. In a time before writing, moreover, information was principally communicated orally. It seems reasonable that prehistoric humans would have paid more attention to their acoustic landscapes than we do today. "Senses as a whole were more fused," says Julian Thomas, an archaeologist at the University of Manchester, UK. "There wasn't the separation of vision from the other senses as there has been over the last few centuries. Nowadays we tend to prioritise vision."
We also know that our ancestors appreciated their ability to exploit their environment to make sound early on. The discovery of three flutes in 2009 in a cave in south-west Germany, the best preserved of them made from a vulture's wing bone and containing five finger holes, pushes the origins of music back to the middle Palaeolithic era, 40,000 years ago.
Lithophones or rock gongs- stones that create a tone when hit- are found around the world. A cave at Fieux à Miers in the Midi-Pyrénées region of the south of France contains a 2-metre-tall feature which resonates like a gong when struck. Recalcified fractures on the lithophone indicating where it was struck can be dated back to the upper Palaeolithic, around 20,000 years ago (Oxford Journal of Archaeology, vol 4, p 31). Outdoor examples include Kupgal Hill in Karnataka state, southern India, where an outcrop of dolerite boulders emits loud ringing tones when hit with granite stones. Nicole Boivin of the University of Oxford suggests that shamans might have used the rock gongs during formal rituals. Dating the wear marks in boulders is impossible, but the presence of Neolithic rock art indicates that the site was used for many thousands of years (Antiquity, vol 78, p 38).
Imagery such as cave paintings, markings or etchings also provides tantalising clues to how prehistoric humans might have exploited their surroundings to make sound. Iegor Reznikoff of Nanterre University, Paris, has examined the caves of Rouffignac in the south of France and showed that paintings are located where the most interesting sound effects are heard. Devereux, in his book Stone Age Soundtracks, cites numerous other examples around the globe of seemingly premeditated placing of petroglyphs or pictographs, including sites where art is painted on concave rock walls that give distinct echoes.
Systematic analyses of such sites are few and far between. Rupert Till, a musicologist from the University of Huddersfield, UK, says acoustic archaeology is where conventional archaeology was a century or more ago. "The subject is in its infancy," he says. "It's like the days of the Victorian gentleman wandering around digging holes in the ground."
It is one thing to show that our ancestors were aware of their acoustic environment. It is quite another to prove that they intentionally designed their surroundings with acoustics in mind. As soon as humans began constructing their own dwellings and other structures, this question of "intentionality" looms large.
One focus of this debate lies with enclosed spaces such as burial mounds, underground temples and burial chambers dug out of rock and earth. In the 1990s, Devereux and his colleagues measured the acoustics of six sites in the UK and Ireland dating from around 3500 BC to 400 BC, and found that all of them have resonant frequencies between 95 and 120 hertz, within the range of a male voice. Chant in a drone at the right frequency and you can map out the shape of the acoustic resonance, hearing the sound loud in one place and hardly at all in another- a dramatic and impressive sound effect (Journal of the Acoustical Society of America, vol 99, p 649). "Certainly this would have been a dense sensory experience," says Thomas- one accentuated by tight squeezes, poor light and the stench of rotting bodies.
Devereux thinks this is no coincidence: the spaces were tuned to maximise the acoustic impact of ritual chanting. The burial mounds consist of a stone chamber and entrance passage covered in earth. In theory, at least, the builders could have moved stones around and tuned the chamber before piling on the earth, perhaps copying previous burial mounds with particularly good acoustics. Similar claims of acoustic tuning for religious purposes have been made of pre-Inca temples in Peru (New Scientist, 6 September 2008, p 37).
It's a nice theory, but not everyone is convinced. Matthew Wright, an acoustics researcher at the University of Southampton, UK, is scathing in his commentary. "If you are going to conclude that particular burial mounds were designed for chanting, then you have to also conclude that my bathroom was made for singing," he says.
Till thinks that this argument overlooks how unusual stone buildings were in the past, and therefore underestimates the amount of thought that would have gone into building them. Both he and Devereux accept that acoustic intent in the design of burial mounds is far from proved, and it will be difficult to do so conclusively. Till suggests that proof might come in identifying repeat features in burial mounds that change over time, indicating an empirical development process.
Nevertheless, he thinks that some of the evidence brought for ancient acoustic effects is judged too harshly. If artefacts or monuments look good, then we believe with little hard evidence that they were designed to look good. Where interesting sound effects are heard, though, we dismiss them as flukes or demand evidence for acoustic purpose- perhaps because, in our noise-filled modern environments, we are far more attuned to visual cues than acoustic ones.
Acoustic consultant David Lubman agrees. In 1998 he suggested that the curious echo reflected from the steps of the El Castillo pyramid at the Mayan site of Chichen Itza, Mexico, was no accident. The steps had been designed, he said, to generate a sound that resembles the chirping of the quetzal, the sacred bird of the Mayans.
Many archaeologists dismissed his idea. "Some of this is understandable," says Lubman. "Many outsiders promote unscientific, ignorant, and even superstitious ideas." But acousticians have a crucial role, he says, in getting archaeologists to recognise the visual bias they bring to their studies.
Posted by Arcturus
30th August 2010ce
Edited 5th September 2010ce