British researchers conducted experiments at a Stonehenge stand-in as well as the actual 5,000-year-old monument to determine how sounds echoed within the ancient circle of stones — and they found that the sounds would have taken on an eerie reverberation.
"We can expect such a space to have a striking effect on someone of that time, identical to what we feel nowadays when we go into a church," the University of Salford's Bruno Fazenda, who orchestrated the research project, told me in an email.
The study is described on the university's website in a technical analysis as well as a news release issued last week, but the upshot is that the Neolithic people who gathered inside the circle could well have had a religious aural experience. That meshes with the view of most archaeologists that the monument on England's Salisbury Plain took on the trappings of a place of healing — a "Neolithic Lourdes," if you will.
It's not easy to reconstruct the sounds of ancient Stonehenge: For one thing, many of the standing stones are missing from what was thought to be their original places, ruining the acoustic arrangement. For another thing, researchers are not allowed to run electrical power out to the site, or bring in a generator. That limits the types of sound equipment and scientific instruments that can be used on site.
Replicating the reverb
Fazenda and his colleagues from the University of Huddersfield and the University of Bristol found a couple of clever solutions to those challenges. They brought air-filled balloons to the Stonehenge site in 2009, then popped the balloons with a needle and recorded the reverb with a microphone and a digital field recorder. The reflected sounds of the pops were hard to make out, but they appeared to follow a pattern of 1-second reverberation time at midfrequencies, for locations that were within the ruins of the stone circle.
To study the reverberation patterns in detail, the team headed off to the Maryhill Museum in Goldendale, Wash., which has a full-scale concrete replica of Stonehenge on its grounds. The monument was built by millionaire industrialist Samuel Hill as a tribute to fallen World War I servicemen. The museum let the researchers make their measurements with more sensitive instruments, powered by on-site generators. The same balloon-popping technique was used, and the readings confirmed the reverberation pattern that the team found at the real Stonehenge.
"For an outdoor space, the stone circle exhibits quite a 'live' acoustic environment," Fazenda said. "In the Neolithic, such an environment was not very common at all. The only spaces that might sustain reverberation were caves and perhaps some natural features such as opposing cliff faces."
Fazenda said the echo effect would be much more like what you hear in a cathedral than in a concert hall.
"The center of the space has potential for some focusing effects," he said. "That's the point where all reflections arrive at the same time, and with the largest gap relative to direct sound. On paper we would expect that to sound striking. However, there are quite a lot of scattering effects from the stones, so the clear echoes are somewhat destroyed by it."
He stressed that it's not at all clear whether Stonehenge was designed with the acoustics in mind, but he and his colleagues do think that the setting would have added a special something to drumbeats, chants or music inside the stone circle.
Fazenda, who teaches audio production at Salford, has been working on this project for the past four years on an unfunded basis. "It has been a kind of 'research hobby' that I have managed to do after hours (don't really call it spare time)," he wrote. He believes the project could break new ground in the field of archaeoacoustics — the study of the sound characteristics of ancient spaces.
"The original focus was on studying the acoustic response of the space," he said. "The recent output has been that we replicated it using wavefield synthesis, which immerses you in a sound field, thus giving you the most approximate aural experience that you could get of being in the space. That was shown at a few recent events, and we have a permanent demo in our labs here at Salford. A wavefield synthesis system uses +64 channels and speakers, so it is not really portable."
Such a system can be tuned to provide a virtual-reality sense of the sounds of Stonehenge, as well as the sounds of other ancient settings that are no longer configured the way they were in their heyday. Want to hear the roar of the crowd in the Roman Colosseum? There's a wavefield synthesis app for that.
Fazenda is preparing a paper on his "research hobby" for Acta Acustica, the journal of the European Acoustics Association. He's also writing a chapter for a book on the acoustics and music of British prehistory. (For more on that subject, check out the website of the Acoustics and Music of British Prehistory Research Network.)
You can expect to hear more about the sounds of Stonehenge in the months and years ahead. In the meantime, give a listen to these sound files, and follow the Web links for more about archaeoacoustics.
Stonehenge sound files:
- Hand-clapping outside and inside the Maryhill stone circle (via Sonic Wonders)
- Univ. of Salford's rendering of a song with Stonehenge-style reverb (WAV file)
- Sounds of Stonehenge ... including a podcast on sound heritage
More about archaeoacoustics:
- Scientists revive sacred sounds
- Was Stonehenge inspired by a sound illusion?
- It turns out that cavemen loved to sing
- Stonehenge: Totally awesome place for raves
- Researchers re-create scary pre-Columbian sounds
- Acoustic archaeology yields mind-tripping tricks
- Listen to the sounds of science
Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding Cosmic Log's Google+ page to your circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.