Introduction
At Stonehenge Aotearoa many visitors are fascinated with the acoustic qualities of the stones. They wonder if the effects they encounter are akin to those that would have been experienced in Stonehenge on Wiltshire Plains, England thousands of years ago.
This article is based on the investigation work published by Dr. Rupert Till of University of Huddersfield in his paper “Song of the Stone: An Investigation int the Acoustic Culture of Stonehenge.”
The original Stonehenge, built over 1500 years starting 5000 years ago, features unique stone settings with sarsen and bluestones. The site is believed to have served as a ritual location, aligned with solstices, with theories suggesting it was a burial site or a healing centre.
Acoustic properties of Stonehenge, England.
This section discusses the acoustic properties of Stonehenge, including resonance, reverberation, and their potential cultural significance.
- Watson and Keating (1999) identified modal resonance and low-frequency filtering in Stonehenge, suggesting intentional shaping of the stones to enhance acoustics.
- A project involving Dr. Bruno Fazenda included theoretical analysis, tests at a replica, and measurements at the actual site.
- Theoretical analysis indicated that Stonehenge could produce reverberation due to its circular arrangement and reflective stone qualities.
- The fundamental resonant frequency of Stonehenge was calculated to be approximately 10Hz, associated with alpha brain waves linked to relaxation and meditation.
- Frequencies below 20Hz can be perceived as vibrations or rhythms, challenging the myth that they are inaudible.
- The mathematical model predicted two strong modal resonances at about 48Hz, reinforcing specific sonic effects within the space.
- The positioning of the Slaughter and Heel stones was found to interact with the acoustics at the centre, enhancing the overall sound experience.
- The research suggests that circular ritual spaces like Stonehenge may have been designed with acoustic effects in mind, similar to other historical structures.
Maryhill model of Stonehenge is a replica of England’s Stonehenge located in Maryhill, Washington, United States.
- The original Stonehenge structure is incomplete, with many stones missing or fallen, complicating acoustic testing.
- A concrete replica of Stonehenge in Maryhill, Washington, was used for acoustic tests despite its differences from the original.
- The Maryhill Monument’s acoustic results were conservative due to its porous concrete, which produced weaker reflections than the original stone.
- Acoustic tests showed a reverberation time (0) of 1.5 seconds and an early decay time (EDT) of 0.8 seconds.
- The strongest resonance was found at approximately 48Hz, matching predictions from a theoretical model.
- Audio recordings captured the changes in sound due to modal resonance, illustrating the acoustic effects present in the space.
Experiments demonstrated that modal resonance could be achieved using prehistoric-style percussion instruments, producing significant standing waves. The study highlighted the importance of acoustic properties in the selection of stones for the original Stonehenge.
Acoustic analysis of Stonehenge
Acoustic analysis of Stonehenge used digital modelling and real-world testing to understand its sound properties. Dr. Bruno Fazenda led a Stonehenge research project with support from various experts and organizations, including the History Channel and the University of Sheffield, utilizing a dodecahedron loudspeaker and digital models. Key contributions came from Prof. Mike Parker Pearson and Dr. Ben Chan, enhancing archaeological insights and discussions.
- The acoustics of Stonehenge were studied using Odeon software, revealing high envelopment and suitability for rhythmic music.
- Clarity (C80) measured at -5.2, and Definition (D50) at 0.19, indicating lower performance for speech compared to music.
- Reverberation Time (0) was predicted at 2.36 seconds, while real-world testing showed a lower value of 0.75 seconds.
- Acoustic testing involved balloon bursts and instrument sounds, with clear echoes recorded, particularly from high-frequency small drums.
- The modelling results were consistent with previous findings from Maryhill, supporting the idea of Stonehenge’s unique acoustic environment.
- Digital auralisations recreated the sound of Stonehenge as it may have been 5000 years ago, highlighting the impact of stone placement.
- The research emphasized the importance of acoustic stratification, suggesting certain positions held more significance during rituals, revealing 70% sound amplification in specific areas.
The study indicates that the missing stones affected the acoustics, but echoes and reverberation were still measurable in the existing structure.