SINGAPORE - Next month, somewhere in a public square in Singapore, a security camera will "sing" a libretto.

Pedestrians will be under remote surveillance by a woman in Melbourne, who will - without being visible to them - comment on the scene, issue instructions and sing in real time.

This, in broad brush strokes, is what audiences might expect at interdisciplinary performer Sophia Brous' world premiere of The Invisible Opera at the Singapore International Festival of Arts.

The production responds to the multifarious activities that go on in a public square, as well as ideas of surveillance, public assembly and freedom of movement. It will feature sound design, electroacoustic orchestration and live vocals.

"Sometimes sound exists as an accompaniment to theatre," says the 35-year-old Australian, who is also a respected arts curator. "It's used as a device. In this work, I hope sound can be a vector of drama and action.

"Sound becomes an enabling, immersive tool to dramatise the city and animate everything we see. It invites the audience to question what is and isn't theatre, both within the piece, but also within our everyday lives."

Brous says she spends a lot of time people-watching in Melbourne and New York, the two cities where she is based.

"What's the sound of the sandwich being eaten by the gentleman in the corner? What are the sounds of electric bikes and scooters?

"When people think of opera, they think of large-scale scenography, the grandeur and romance of epic opera performance.

"But I was really interested in how it interacts with the mundane, with the everyday. I was noticing what people were doing in these spaces, noticing what seemed like impossible, staged behaviours - but of course they weren't staged."