As part of the Wuji Ensemble’s Beyond the Senses concert series in January, audience members were invited to take part in a relaxation session on the roof of the Asia Society’s Hong Kong headquarters in Admiralty. Afterwards they filed downstairs and took their seats in the Jockey Club Hall to experience a mesmerising modern performance featuring traditional Chinese instruments and poetry.

Sat with an array of shining bowls, Tsang closed the show with five minutes of precision bowl striking, letting each send out vibrations and dispatching concertgoers with moony smiles, loose limbs and a feeling of lightness. It’s a sensation Tsang terms “eternal now”, a state where “it feels like the past and future are an illusion”.

“Singing bowls have a very special frequency – different to other musical instruments – which seems to make time expand and slow down,” he says.

Tsang, 45, who built his career in the performing arts as a set designer and performer, first discovered singing bowl music a decade ago in Taiwan after being introduced by a friend. He became fascinated by its relaxing properties.

“It was the sound I’d been looking for a long time. When I heard it, everything just stopped; there was nothing to think,” he says. However, his motive for learning how to play singing bowls was to help his mother manage the symptoms of her diabetes in a way that didn’t involve taking ever more medication.

“I wanted to find another way to make her more comfortable,” he says. “I researched many methods, like massage and acupuncture to help her get rest. After I heard the bowl, I felt it would be the best thing for her. I played for her and she fell asleep within five minutes. We didn’t know how it worked, but at least I could make sure she was very relaxed.”

In December 2018, Tsang released “The Seed of Sound”, two albums of original compositions on three CDs, each with a different theme. The first, Silence in the Woods, is designed to feel like “entering the forest to help listeners connect with nature”, while the second, The Voice of Void, is themed around daylight and inspired by the sun to promote focus and inner strength, Tsang says. The third, Meditation Nocturne: A Pliable Heart, features some of Tsang’s softest work; the tracks are longer and more meditative, inviting somnolent ruminations on moonlight and nightfall.

Singing bowls date back to China’s bronze age Shang dynasty more than 3,000 years ago, but they are popular throughout Asia, especially for use in Buddhist rituals.

Recently, Western cultures have used the bowls for alternative healing, sound therapy and relaxation.

Urban health and fitness centres, such as the Enhale Meditation Studio in Hong Kong, base their entire programme around a menu of “sound bath” experiences, including gongs and crystal, Himalayan or Tibetan bowls.

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There are technical considerations to playing singing bowls: a humid environment works best, as water molecules in the air enhance their resonance. Bowls can be made from 12 types of metal, invoking the most sonorous vibrations calls for bowls containing a high percentage of copper, and these are preferred in Nepalese culture.

The way the bowls vibrate has been widely studied.

“A Tibetan bowl, generally made from a bronze alloy containing copper, tin, zinc, iron, silver, gold and nickel, is a type of standing bell played by striking or rubbing its rim with a wooden or leather-wrapped mallet. This excitation causes the sides and rim of the bowl to vibrate, producing a rich sound,” note authors Denis Terwagne and John W.M. Bush in the Institute of Physics journal Nonlinearity. (A common dinner party trick is making a wine glass sing by running a moistened finger around the rim; however, the Tibetan singing bowl is easier to excite than a wine glass, since its resonant frequency is much smaller.)

However, it is hard to say why certain listeners are more susceptible to their lulling effects. Singing bowls feature prominently in relaxation videos on YouTube, although capturing their sound faithfully requires powerful microphones and as little external noise as possible.

“So many CDs can’t get the right quality because it’s difficult to get the resonance … We spent seven years experimenting how to record the bowls best,” says Tsang.

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“I had to make sure there were none of my breath and movement sounds. At first it wasn’t successful, so we did lots of experiments with good microphones and a very good producer. Now the quality is high enough that for people who want to lie down and listen, it sounds like a live performance.”