Sacred sound: chant, bells, bowls and the stone chambers that ring

What is sacred sound?

Sacred sound is any sound a tradition uses for worship, prayer or ritual. The same few forms turn up across the world: chant and mantra, sung or spoken over and over; bells that mark an hour or a threshold; bowls and gongs struck and left to ring; and the drone, one low note held under everything else, as the tanpura holds it under Indian music. Nearly all of them rest on the human voice or on a long, sustained tone.

The meaning of each sound belongs to its tradition, not to its acoustics. A mantra matters to the person reciting it because of what it says and who taught it, and no measurement adds to that or takes it away. What science can measure is the sound itself and the room it is made in. This guide follows those measurements back to some of the oldest rooms anyone has tested, the stone chambers said to ring at 110 Hz, and then to what is known about listening, chanting and singing bowls today.

Why is 110 Hz linked with ancient stone chambers?

Because of one acoustic survey in the 1990s. The engineer Robert Jahn, the archaeologist Paul Devereux and the physicist Michael Ibison carried a sound generator and meters into six ancient chambers: Wayland's Smithy, Chun Quoit and Carn Euny in Britain, and Newgrange and two cairns at Carbane West in Ireland, as the Science Frontiers digest of their first report lists them. Five date from about 3,500 BC and one from about 500 BC. The chambers had very different shapes, cruciform, rectangular and beehive among them, yet in the words of their 1996 paper each one

sustained a strong resonance at a frequency between 95 and 120 Hz

The authors noticed that this range sits inside the adult male voice, and allowed themselves one guess: "one may speculate that some forms of human chanting, enhanced by the cavity resonance, were invoked for ritual purposes." The single number came later. The guitar's open A string plays at 110 Hz, close to the middle of the range, and Devereux went on to suggest that sound at 110 Hz might have a special effect on the brain, as the acoustician Matthew Wright later summed up the story (Wright, 2007). So 110 Hz is a round figure for the middle of a measured range, not a reading taken in any one chamber.

Is 110 Hz the pitch of a chanting voice?

It is the pitch of a man's speaking voice. The voiced speech of a typical adult man has a fundamental frequency from 90 to 155 Hz, and that of a typical adult woman from 165 to 255 Hz, as Wikipedia's article on voice frequency sums up the standard figures. The band the six chambers rang in, 95 to 120 Hz, lies wholly inside the man's range and below the woman's. 110 Hz is also a note: with A tuned to 440 Hz, the usual convention, it is the A two octaves lower, and 220 Hz, its octave, sits in the middle of a woman's speaking range.

The numbers behind the chart

What was measured	Frequency	Source
A typical man's speaking voice	90 to 155 Hz	Wikipedia, voice frequency
A typical woman's speaking voice	165 to 255 Hz	Wikipedia, voice frequency
Six chambers, Britain and Ireland, each one's strongest resonance	95 to 120 Hz	Jahn, Devereux and Ibison, 1996
Hypogeum, Malta, Oracle Room	70 and 114 Hz	Debertolis, Coimbra and Eneix, 2015
Hypogeum, Malta, Oracle Chamber, primary resonances	41, 72 and 76 Hz	Till, 2017

A chamber that rings between 95 and 120 Hz answers a low male voice most strongly, which is where the idea of chanting priests comes from. Later surveys found that this was not the whole story, as the next sections show.

Why does a stone chamber ring at all?

Because sound reflects between facing walls. At a pitch whose half wavelength fits the gap between two walls a whole number of times, each reflection lines up with the sound arriving, and the room holds that note as a standing wave. These axial modes, between two opposite surfaces, are a room's strongest, since, as an acoustics primer from Indiana University puts it, they "have the least attenuated reflections".

The arithmetic is short. Sound travels about 344 metres a second in air at 20 °C, so one wave of 110 Hz is 344 ÷ 110 = 3.13 metres long, and half a wave is 1.56 metres. Walls 1.56, 3.13 or 4.69 metres apart all ring at 110 Hz. In a chamber 3.13 metres across, the air pressure swings hardest at both walls and at the centre, and hardly at all a quarter of the way in from each wall. Jahn's team found the same shape: strong antinodes, the loudest points, at the outer walls.

Run the sum the other way and the whole band of 95 to 120 Hz is a half wavelength of between 1.43 and 1.81 metres. Most stone chambers are a few metres across, so somewhere in that band almost any of them will find a note to hold.

Were the chambers built to ring?

Nobody has shown that they were, and the strongest acoustic argument says the ring would be there anyway. Matthew Wright, of the University of Southampton's Institute of Sound and Vibration Research, counted how many resonances rooms the size of the six chambers should have, using a formula Hermann Weyl derived in 1912. It predicted more than one resonance in the band in all but the smallest chamber, and just under seven in the largest. His conclusion:

it would have been surprising if these chambers did not have resonances between 95 and 120 Hz

The evidence that they were designed for chanting, he wrote, "is no stronger than it is for a typical bathroom". Anyone who has sung in the shower has heard the same effect.

Malta's Ħal Saflieni Hypogeum, a Neolithic complex cut into the rock, shows how much depends on who measures and how. A team reported "a double resonance frequency at 70Hz and 114Hz" in its Oracle Room in 2015, one that a male voice tuned to those pitches could set ringing through the whole complex. Rupert Till of the University of Huddersfield measured the Hypogeum again two years later with a loudspeaker and microphones, noting that "previous studies have lacked rigour". He found the Oracle Chamber's primary resonances at 41, 72 and 76 Hz, reverberation lasting up to 16 seconds at 63 Hz, and speech that is unintelligible beyond very close range. He also turned the chanting story round:

Previous male-focused interpretations may be the result of male authors testing male voices.

In his reading, women's singing voices would give the best balance of resonance and clarity in the space, and slow chanting in long syllables would carry well. That is a judgement about how the room sounds, not evidence of how it was used.

The painted caves of the Palaeolithic, far older than any chamber, offer a different kind of clue. The researcher Iegor Reznikoff sang his way through decorated caves such as Niaux in France and Kapova in the Urals, counting the echoes his voice drew from each place, and reported that "most of the images are situated in the most sonorous parts of caves". In narrow tunnels he found single red dots at the point where a voice resonates most. His measure is his own voice and ear, so the finding is suggestive rather than settled, but it points the same way as the chambers: people who made sacred places seem to have noticed where sound came alive.

What happens when people listen to 110 Hz, chant or hear singing bowls?

The research is small, and none of it tests a stone chamber. Four studies come closest to the questions people ask, and each one is set out below with what it looked at, what it found and what it does not show.

Tones near 110 Hz and brain activity

A pilot played tones of 90, 100, 110, 120 and 130 Hz to 30 healthy adults while recording their brain activity with EEG (Cook, Pajot and Leuchter, 2008). It reported that "activity in the left temporal region was found to be significantly lower at 110 Hz than at other frequencies", and a shift at the front of the brain from left towards right. The authors called it a pilot and asked for a wider study; Harmonance found none published since. A change in a brain recording is not a benefit, and the paper's summary does not say how loud each tone played or for how long.

How calm a 110 Hz tone sounds

In an online test at the Australian National University, 37 adults rated twelve pure tones, 110 Hz the lowest of them, for how happy, sad, calm and angry each sounded (Kumar, Abhayapala and Samarasinghe, 2022). 110 Hz was rated the calmest of the twelve, about 8.3 out of 10, and also the saddest, about 6.1, as read from the paper's graph. The listeners judged how each tone sounded, not how they felt, and the tones always came in rising order, so the lowest sat at one end of every comparison.

Chanting Om

A pilot fMRI study scanned 12 healthy volunteers, nine of them men, while they chanted Om aloud, pronounced a long "ssss" or rested (Kalyani and colleagues, 2011). During Om the scans showed reduced activity in the limbic regions, the brain's emotional circuits, the right amygdala among them, and the "ssss" task showed no such change. Twelve people in one scanner cannot show what chanting does in daily life, and reduced activity in a region is not, by itself, calm.

Singing bowl meditation

In an observational study, 62 adults with a mean age of 49.7 years took part in a singing bowl meditation and filled in mood questionnaires before and after (Goldsby and colleagues, 2017). Afterwards they reported less tension, anger, fatigue and depressed mood, and those new to it reported the biggest drop in tension. The authors name the main weakness themselves: "this was a nonrandomized observational study without a control group", so the change cannot be separated from simply lying still on a mat in a quiet room.

What the four add up to

Two small studies at or near 110 Hz, one of them never repeated; one scan of twelve people chanting; one uncontrolled study of a bowl session. None tests a stone chamber and none shows a health benefit. The US National Center for Complementary and Integrative Health sums up research on music in general:

However, because much of the research on music-based interventions is preliminary, few definite conclusions about their effects have been reached.

Why it matters for listening: a low, steady tone is heard as calm more readily than a high one, and sustained sound with the voice is what these traditions have in common. A safe way to try it is a few minutes at a volume you could easily talk over, seated, humming along if you like. The nearest tone on Harmonance is the 111 Hz page, played with Strings off.

What does the 111 Hz page play?

Harmonance has no 110 Hz page; the nearest tone it plays is 111 Hz, 15.7 cents above 110 Hz, where a cent is a hundredth of a semitone. Played together, the two would beat once a second, since they differ by 1 Hz. Both sit well inside the chambers' band. Harmonance measured both versions of the page's sound from its own audio files, against the band the six chambers rang in.

The numbers behind the chart

Band	Tone alone	Strings
Below 95 Hz	0%	5.9%
95 to 120 Hz, where the chambers rang	99.5%	6.4%
120 to 255 Hz	0.5%	46.3%
Above 255 Hz	0%	41.4%
90 to 155 Hz, a man's speaking voice	99.5%	17.7%

Download the measurements (CSV)

With Strings off, the page plays one tone, strongest at 110.99 Hz, and 99.5% of its energy sits between 95 and 120 Hz, inside the chambers' band and inside a man's speaking range. That is as close to the sound of a ringing chamber as a single tone gets.

With Strings on, the arrangement keeps the note but spreads it upwards. Only 6.4% of the sound stays in the chambers' band; 46.3% lies between 120 and 255 Hz, and 41.4% above 255 Hz. Its strongest line is at 167.4 Hz, close to 166.5 Hz, the fifth above 111 Hz. So for the chamber sound, keep Strings off; switch them on when you want the same note as music.

How do you take part in sacred sound with respect?

Start with whose sound it is. Most sacred sounds belong to living traditions, Hindu, Buddhist, Christian, Jewish, Muslim and many more, and each has its own words, teachers and occasions. Learning a little of where a chant or a bell comes from, and naming it when you share it, keeps its meaning intact. Avoid selling a sacred sound as a remedy or a shortcut; the traditions themselves rarely claim that.

Use your own voice. The tone on the 111 Hz page is easy to hum against for a low voice; a higher voice can hum the octave above on the 222 Hz page. The guide to using your voice gives a simple way in, and the 136.10 Hz Earth year tone, often called the Om tone, is another low drone to chant with.

Keep it quiet. Loud listening is the one risk that is well established: the US National Center for Complementary and Integrative Health notes that "listening to music at too high a volume can contribute to noise-induced hearing loss", and the World Health Organization's safe listening advice keeps a device's volume at no more than 60% of maximum.

For more, the 111 Hz guide follows the angel number side of the same tone, a quiet moment to reflect gathers tones for sitting with one question, what the science of sound healing shows sets out the wider research, and in Harmonance Studio you can set 111 Hz beside other tones and build your own drone.

Sources and limits

The chamber measurements come from the six-site survey, read through its abstract and a digest of its first report, and from two surveys of the Hypogeum, one of which criticises the other. The arithmetic of wavelengths and the voice ranges are standard figures, worked in full above. The cave finding rests on one researcher's own voice. The studies of listeners are small: two pilots, one rating test and one uncontrolled study, none of them about a stone chamber. The measurements of the 111 Hz page are Harmonance's own, made from the page's audio files. No listener's words are quoted here.

1. Science Frontiers 102 (1995), Ancient acoustical engineering, a digest of the Jahn team's first report: the six sites, their shapes and the first report's abstract.
2. Jahn, Devereux and Ibison (1996), Acoustical resonances of assorted ancient structures, Journal of the Acoustical Society of America 99(2): 649 to 658: each chamber's strongest resonance between 95 and 120 Hz, and the chanting idea.
3. Wright (2007), a Neolithic burial chamber compared with a bathroom, acoustically, Acoustical Society of America lay language paper 3pAA4, University of Southampton: why rooms of that size ring in that band, and where 110 Hz came from.
4. Wikipedia, Voice frequency: the fundamental frequency of typical adult speaking voices: the typical speaking ranges of adult men and women.
5. UNSW Music Acoustics, Note names, MIDI numbers and frequencies: A at 440 Hz and the notes below it.
6. Hass, An Acoustics Primer, chapter 1.13: standing waves in rooms, Indiana University: standing waves and axial modes in rooms.
7. Hass, An Acoustics Primer, chapter 1.3: the speed of sound, Indiana University: 344 metres a second at 20 °C.
8. Debertolis, Coimbra and Eneix (2015), Archaeoacoustic analysis of the Hal Saflieni Hypogeum in Malta, Journal of Anthropology and Archaeology 3(1): 59 to 79, University of Malta repository: the Oracle Room's resonances at 70 and 114 Hz.
9. Till (2017), An archaeoacoustic study of the Hal Saflieni Hypogeum on Malta, Antiquity 91(355): 74 to 89, the author's copy at the University of Huddersfield: the Hypogeum measured again, and the male-voice reading questioned.
10. Reznikoff (2013), The acoustic dimension of Paleolithic painted caves and stones, Palethnologie 5: images and red dots at the most resonant places in painted caves.
11. Cook, Pajot and Leuchter (2008), Ancient architectural acoustic resonance patterns and regional brain activity, Time and Mind 1(1): 30 adults, five low tones and EEG.
12. Kumar, Abhayapala and Samarasinghe (2022), A Preliminary Investigation on Frequency Dependant Cues for Human Emotions, Acoustics 4(2): 37 adults rating twelve pure tones, 110 Hz among them.
13. Kalyani and colleagues (2011), Neurohemodynamic correlates of OM chanting: a pilot functional magnetic resonance imaging study, International Journal of Yoga 4(1), PubMed Central: 12 volunteers chanting Om in an fMRI scanner.
14. Goldsby and colleagues (2017), Effects of singing bowl sound meditation on mood, tension, and well-being: an observational study, Journal of Evidence-Based Complementary and Alternative Medicine, PubMed Central: 62 adults before and after a singing bowl meditation, with no control group.
15. National Center for Complementary and Integrative Health, Music and Health: What You Need To Know: the state of music research, and loud listening.
16. World Health Organization, Deafness and hearing loss: safe listening: safe listening and device volume.