martes, 6 de mayo de 2014

Songs from the caves

Significant evidence now exists for the importance of sound in prehistory and research in this area has progressed  over the past 30 years, with a number of archaeological finds that are thought to be musical instruments found in caves associated with palaeolithic occupation. Particularly well known are bone flutes of Aurignation date some 35-40,ooo years old and fairly advanced examples of an aerophones (bull roarers) from the same period. This shows the complex nature of instruments, yet surviving artefacts are not the sole method of examining prehistoric sounds.

Establishing a baseline dataset

The project “Songs from the Caves” explores the acoustics of prehistoric painted caves in Northern Spain, to establish whether a secure relationship can be found internally between the positioning of motifs and sonic effects.  Sound has the potential to provide information that is not available by only studying visual or material properties.
The project seeks to document the relationship of rock art and the acoustic characteristics of the spaces in which the paintings were made, providing two sets of complimentary quantifiable datasets that can be compared and analysed.
Reznikoff and Dauvois (1988) suggested a link between the positioning of cave paintings in southwest France and the patterning of acoustic resonances, reverberation and echoes. However the methodology used was not based on rigorous acoustical analysis, and was critiqued for being somewhat subjective with researchers using their own voices to search for vocal effects. The new research tests their original theory using a rigorous scientific methodology.
Dr Rupert Till (University of Huddersfield, UK) and Dr Bruno Fazenda (University of Salford, UK), who had together previously explored the acoustics of Stonehenge, visited caves in Asturias and Cantabria in the summer of 2012 to carry out a pilot study. Fazenda, Till and Professor Chris Scarre (Durham University, UK) then carried out a fully funded research project in 2013.

Acoustic properties of the caves

Acoustics within a cave are strikingly different from those outside and the first thing to note is that many simple activities in the cave would have made sound; talking, moving, grinding and preparation of pigments for painting.
A high quality digital record made between 2004 and 2007 of the imagery within Tito Bustillo cave (Spain) resulted in the discovery of unknown decorated spaces, and a pit within the Gallery of the Anthropomorphs that contained ochre and crushed bone along with teeth and shell that dated to around 33,000 years BP, suggesting a far greater age than previously thought for at least some of the imagery.
 
The sound of the Palaeolithic

The Songs of the Caves project investigated the acoustic environment of the Asturian cave of Tito Bustillo, as well as four Cantabrian caves – La Garma, El Castillo, Las Chimeneas and La Pasiega.
The researchers used a range of devices including reconstructions of Palaeolithic bone flutes and bullroarers, as well as drums, bark rattles, cow horn trumpets, bones, wooden sticks and even river pebbles to excite the acoustic space with human voices also added. The level of background noise was as low as the equipment was capable of measuring – far lower than a quiet environment outside which makes acoustical effects inside the cave particularly striking.
Small, simple percussion instruments such as river stones and bones hit together were notably effective. Drums had powerful effects in all situations, as they produce lower frequencies loudly enough to stimulate effects not otherwise heard. Natural reverberations enhance the sounds of voices and bone flutes. The long reverberation times of the main open central space make speech difficult to understand, but support a wide range of musical sounds. When heard from a distance the effect of reverberation makes it difficult to locate the source of sounds, which within the cave could be heard from as far as 50 metres away.

Associated images and sounds

Scientists also found that sounds associated with the imagery were particularly effective – for example using a cow horn to play a single note in front of a bovine image, or simulating the bellow of a bull by vocalizing along with the pitched note of the horn.
Marimba sticks were used to test the lithophone in Tito Bustillo, which produced a range of notes. Over 50 stalagmites – some near the lithophone – produced clear ringing notes. Some are over a metre tall and produce a powerful low note. As drops of water fall on stalagmites, notes ring out from time to time by themselves.
Experts investigated correlations between acoustics and archaeology, recording five characteristics related to paintings and motifs; type of decoration; colour; number of images; chronology; and depth within the cave.
The team also tried to find positions at which to take measurements where there were no images, but imagery would have been possible – for example on flat, blank wall panels.
With one exception, all comparisons of acoustical parameters between decorated and non-decorated caves were statistically significant, suggesting a different acoustic response where decorations are found.
Tito Bustillo has reverberation in a main central space of up to 2.5 seconds, today considered an almost ideal value – quite high for a concert hall, low for a church and certainly lower than many cathedrals.
The term ‘live’ is used for spaces with reverberation, and ‘dead’ for those without, and these are useful ways of thinking about how these spaces would have been perceived. The acoustics of a place could have influenced whether it was selected as the position of a painting or engraving.
Caves such as these were the only places where Palaeolithic people would have encountered such acoustic effects. This project provides some evidence of how sounds could have contributed to a sense that these were places of importance.

Source: Past Horizons:
http://www.pasthorizonspr.com/index.php/archives/05/2014/songs-from-the-caves

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