A cool gust of air cuts through the heavy atmosphere, and Ngui stops in his tracks, transfixed by the incongruous sounds of skateboarders filtering in from outside. When he first came across this sound anomaly he was inspired, he says.
"You're in this steamy area, and then suddenly you get this breeze and the outside society comes in," he says. And it is this transportation of sound from one space to another that Ngui is trying to achieve with his site-specific installation now at the Hayward.
Head down to the grey concrete mass of the South Bank, and you'll find the doors to the Hayward Gallery locked. A livid yellow chair, however, is nailed to the ground outside the main entrance, and stands out like a well-placed banana on a grimy concrete pavement. A drainpipe hangs next to the chair, at ear level, transporting the inner gurglings and sounds of gallery life to the world outside.
Installation with Grey Pipes, by Ngui, 36, serves two purposes. It provides an audio window into the dark, hidden recesses of the gallery that are usually out of bounds to the public and acts as a tantalising taster to the forthcoming exhibition Cities on the Move, which can be heard being put together. Press your ear to the end of the pipe and the effect is much like that of a sea shell, only more intensified, with the rushing background noise becoming almost deafening while in the distance voices shout, and hammers get to work.
"It shows people outside what's going on inside and those inside what's going on in places out of sight," explains the softly spoken, Singapore- born artist.
The Hayward is crawling with Ngui's tentacle-like plastic drainage pipes, carrying sounds between different areas chosen by the artist. The 500ft network of pipes, suspended from the ceiling on thin wire threads, zigzags across the galleries, around walls and through the odd door, before bursting out into the world to run riot over the building's exterior.
One pipeline has escaped from the top floor gallery and is heading towards the bus stop on Waterloo Bridge while another is making its way to the car park at the back of the Hayward - the exposed plastic tubes conjuring up images of the Pompidou Centre: bringing the sounds of the building's innards outside, if not the actual innards themselves.
"Part of my work deals with communication and representation and I've used the pipes as a possibility for communication between different sites and spaces," explains Ngui.
"With the Hayward, I was just struck by the massiveness and the solidity of this particular building so I was keen to make something a little bit plastic."
The forthcoming Cities on the Move show, which aims to capture the frenetic activity, colour and buzz of East Asian cities, while looking at how cities evolve and where they sometimes go wrong, has been deliberately designed to spill out into London to encourage interaction and parallels to be drawn between the two cities.
Ngui's installation is just one of the carrots being dangled in public spaces: a giant Bollywood-style billboard is set to decorate Jubilee gardens where there'll also be a genuine tuk tuk (taxi) - so evocative of the teeming, high-energy streets of East Asia - to transport people to and from the gallery.
The exhibition is going to be a "noisy, messy and interactive" affair, according to the exhibition organiser, Fiona Bradley, and will take its inspiration from contemporary urban visual culture and the rapid urbanisation of East Asia.
Ngui's work will not only reveal the out-of-sight infrastructure of the gallery, but will also add to the surrounding chaos by highlighting the infiltration of unseen noise in urban life.
A street market installation, which parodies the idea of the bargain shop, will be selling its wares at pounds 1 a shot, while bicycles armed with egg cannons will be lined up opposite footage of riot police in action, ready to hurl their ammunition.
And livid yellow chairs will be seen dotted around the exhibition, drainpipe in tow, just begging to be sat on.
`Matthew Ngui: Installation with Grey Pipes', Hayward Gallery, South Bank Centre, London SE1 (0171-928 3144), until 27 June. `Cities on the Move' is from 13 May to 27 JuneReuse content