Trevor Cox, who spearheads the current investigations, believes that a site's acoustics impact its usage. This understanding led him to apply acoustic research methods to Stonehenge, an essential aspect of archaeological studies. Various theories suggest that Stonehenge could have served as a cemetery, a healing center, or even a celestial calendar, as the gaps in the outer stone ring align perfectly with the summer and winter solstices.
Cox's decade-long investigation discovered that Stonehenge functioned as a massive echo chamber, leading to the hypothesis that it was a venue for rituals attended exclusively by the era's elite. The scaled acoustic modeling technique had never been applied to prehistoric sites before, prompting Cox to explore Stonehenge's unique properties. Utilizing a 1:12 scale replica, he conducted tests in the semi-anechoic chamber at the University of Salford (an almost soundproof room lined with geometric foam on all surfaces except the floor).
Cox obtained a computer model of Stonehenge from English Heritage, which enabled him to recreate its appearance 4,000 years ago. To mimic the ancient structure, 157 stones were 3D printed and arranged accurately, a process that took six months. Acoustic tests commenced after painting the stones gray. Since the replica was 1/12th the size of the original, sound frequencies had to be multiplied by 12. Speakers in the chamber emitted the desired frequencies, and microphones captured the results.
Cox's computer model simulated voices and music, distorting them to mimic the properties of the prehistoric monument. To the researchers' surprise, Stonehenge's open design, devoid of a ceiling or floor, still managed to bounce sound between the stones, keeping it confined within the circle. Voices and music would have been more potent and striking at the center of the structure. The directionality of sound within Stonehenge is a particularly fascinating aspect of the research, as it demonstrates the monument's potential purpose as a unique space for speeches and rituals.
However, the sound reflection of the stones amplifies the voice by 4 decibels, which increases the speech comprehension rate to 100 percent. Ceremonies or rituals performed inside the circle would therefore be "private," excluding anyone outside. Research has already indicated that Stonehenge's surroundings might have cultivated hedges (grass or tree fences), also visually hiding the site from anyone who could not participate. Cox likens the acoustics of a building to the difference between standing in an empty movie theater and a cathedral, although to those of us accustomed to moving in and out of enclosed spaces, a late Neolithic person unfamiliar with the acoustics of walls would have found the effect mesmerizing. The first research results were published in the Journal of Archaeological Science in 2020, but Cox and his team continue to study the acoustics of the site further, exploring, for example, how people in the stone circle might have changed the reverberation of sound. Recently, with miniaturized models of up to 100 people inside the mini Stonehenge, new measurements were made. While our bodies absorb sound, changes in acoustics during ceremonies certainly occurred. Changes also occur based on the position
of the listener, which changes depending on whether we are facing or to the side in relation to the sound source. Side reflection of sounds improves, for example, the quality of music in concert halls. Definitive conclusions about these mysterious prehistoric humans are impossible, but more clues about what they were doing in the stone circle will be published after further analysis of the data by Cox's team later this year.
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