Scientists who analysed 242 chants from seven religious and cultural traditions from across the world have detected shared acoustic features that they say might explain their calming and relaxing effects.
Their study, the first systematic acoustic scrutiny of a 5,000-year-old human tradition, has found that chants across cultures and languages share a mostly flat, slow-changing pitch, a smooth, unbroken voice and simple vowels that place little strain on the chanters.
The findings suggest that “chants tend to be produced with a vocal tract that is relaxed, without effort, tightening, or constriction”, psychologist Valentina Canessa-Pollard at the University of Chichester in the UK and her colleagues have said in their study.
The gentle shifts in pitch may work with the human auditory system, avoiding sudden changes that could raise listeners’ alertness or tension, the researchers wrote in their paper published in the .
“One explanation is that the temporal structure of chants has evolved to slow down breathing and promote synchrony between respiration and heart rate, which in turn enhances relaxation,” Canessa-Pollard told The Telegraph.
They compared 242 chants from seven traditions – Buddhist, early and modern Christian, Hindu, Islamic, Pagan and Shamanic – with 126 songs and 616 speech extracts from 14 languages across 12 regions.
The dataset included Hindu Vedic and Buddhist mantras. “Both traditions provide rich examples of the acoustic signatures they identified,” Canessa-Pollard said. “Slow and steady delivery with minimal articulation.”
Canessa-Pollard said the researchers were exploring the possibility of “convergent cultural evolution” – the idea that similar acoustic forms may have independently emerged across traditions in response to shared needs such as relaxation. “But we cannot fully discount a shared origin and the subsequent divergence and adaptation of chants across different cultures,” she said.
One part of the study found that a moderate tempo of 60 beats per minute produced the highest ratings of pleasantness and relaxation, reinforcing earlier research showing that tempo plays a key role in inducing calm.
Japanese scientists in 2017 had also shown that abrupt pitch changes in instrumental music can raise arousal levels in listeners.
The chants’ temporal structure, the researchers propose, may have evolved to slow breathing and synchronise heart rate and respiration, contributing to relaxation.
In playback experiments, 61 participants listened to 84 excerpts of chants, songs, or speech. They gave chants the highest relaxation ratings, above both songs and speech.
Among the 242 chants analysed, 129 were by women and 113 by men. Each chant was performed by an experienced practitioner, recorded without instrumental or background music and delivered as a single voice to allow precise acoustic analysis.
“Listening to even brief excerpts of chants is sufficient to elicit feelings related to relaxation in listeners,” Canessa-Pollard and her colleagues Andrey Anikin in Sweden and David Reby at the University of Etienne in France wrote.
Earlier clinical studies from India and other countries have also suggested that chanting reduces stress and enhances well-being. Evidence for such effects across chants from different cultures emerged nearly a quarter century ago.
In 2001, Luciano Bernardi, an internal medicine specialist at the University of Pavia in Italy showed that among volunteers who recited either Ave Maria, a traditional Catholic prayer, or the mantra Om, both sets of people experienced “striking, powerful and synchronous” increases in cardiovascular rhythms, pointing to favourable physiological and psychological effects.
A team of researchers at the All India Institute of Medical Sciences in New Delhi had two years ago found through brain electroencephalography that both chanting and listening to Om were linked to changes that induced relaxation and improved attention.