'The singers and instrumentalists let out a volley of mad mutterings and animal sounds... it is impossible not to smile'

I have no idea what to expect when I arrive at T13, the enormous shipyard warehouse in the Titanic Quarter, on Saturday night, July 21, 2012.

T13, which describes itself as an 'urban playground', is developing a reputation as a place where strange, exciting things happen, so the choice of venue augured well. And free ice-cream cones – offered to all guests – are an endearing touch.

It immediately puts you in a sweeter, more receptive mood. But what exactly is on offer? Is NEST an opera? An art installation? An interactive, participatory event?

I know that it was part of the Cultural Olympiad, that delightful national sop to the non-sporty among us, and that it involves personal items donated by members of the public. I just hope to God it won't be sentimental, worthy or twee.

Well, I don't need to worry. In the event, NEST is innovative, moving, surprising, stirring – anything but twee. In fact it is epic (and I don't use this word lightly), in both scale and inspiration.

The vast warehouse was filled with thousands of objects, each of which have a particular meaning or significance to the donor, from the most profound to the most trivial and ephemeral.

Drawing on this random collection, Belfast composer Brian Irvine came up with an oratorio, a dramatic musical composition, that is performed by the Ulster Youth Orchestra and a 500-strong community choir.

The music begins unexpectedly as the audience wander through the warehouse, looking at the objects on display. Individual choir members – who are mingling among us unnoticed – suddenly begin to sing a clear, pure melody, almost like an incantation.

Although each singer is standing separately, their voices find each other in the high space over our heads. The effect is startlingly beautiful. Then the orchestra of young people take their places, the choir join them, and this idiosyncratic eight-part oratorio begins.

Although you can sit down and listen to the music as a straight performance in the usual way, and some people do, that would mean missing out on the unique nature of the event. Far better to drift among the exhibits, reading the labels, squatting down to examine a particular object of interest, as the music swells and rises.

There are a pair of chopsticks (the label reads, 'Never leave home without them'); a hostess trolley and a ticket from the miniature steam railway at Drumawhey. There is a pine cone picked up in the forest on a romantic evening, someone's first pair of ballet shoes, and a copy of Graham Greene's Brighton Rock, donated in memory of an inspiring English teacher.

Irvine's composition responds well to the colourful flotsam and jetsam of the exhibits. This is barnstorming, exuberant music, performed with impressive flair and brio. The youth orchestra in particular display talent and maturity well beyond their years. And the choirs tackle their challenging parts with gusto.

At one point, both singers and instrumentalists let out a volley of mad mutterings and animal sounds, batting them back and forth between them, like a musical zoo. I haven't a clue what it all meant, but it is done with such enjoyment, it is impossible not to smile.

Irvine's oratorio is a rich, multi-sensory experience. There is a pleasing sort of democracy to it, with no dividing line between the performers and the audience. You can walk right up to them, see the brass section firing away on all cylinders, or the percussionists getting a deep rumble out of the timpani.

By the end, most of the audience have instinctively drawn close in a loose circle around the orchestra and choir. We are witnessing something special. I walk away feeling proud that Belfast could produce an event of such curious power and resonance.

Nest is open daily until July 29 at T13