New Queen's Hall Orchestra Barbican, London
What is wrong with concert-goers? A few weeks ago, a packed Royal Festival Hall roared and thundered its approval for the two most boring Mahler performances I have ever heard - the Third and Sixth Symphonies, lifelessly performed by the Boston Symphony Orchestra under Seiji Ozawa. On Tuesday of this week, Wyn Morris and the New Queen's Hall Orchestra gave a Mahler Fourth which, flawed though it might have been in places, was still a real live interpretation: always interesting, sometimes fascinating, and ultimately very moving. And the audience was hardly big enough to fill the Barbican stalls. Well, at least they were politely appreciative.

The success of the Mahler was all the more striking in that it followed two Wagner performances which, though well shaped and played, were hardly scintillating. The Prelude to Act III of Lohengrin gave one enough time to adjust to the sound of the old instruments (mostly from around the turn of the century) and to the occasional technical smear - mostly intonation or slightly scrawny strings. But then it's the very lack of modern hygienic, homogenised perfection that makes the New Queen's Hall Orchestra so intriguing, and ultimately enjoyable - if there's such a thing as "unpasteurised" orchestral sound, this is it. Listening to the Prelude to Parsifal, I really began to understand what Tovey meant when he described the orchestration of Wagner's last opera as "lit up from within". Through the quietly shimmering haze of the string textures, one hears flickering flutes, oboes and clarinets - clearly different colours, like the greens, blues, reds and yellows of a coal flame.

The woodwind instruments also provided some of the most memorable moments in Mahler's Fourth Symphony. At the heart of the first movement is a little march, marked "Flowing but not hurried", for four flutes in unison. Played on the wooden flutes Mahler knew, not their modern metal descendants, it is an indescribably lovely sound - soft, enticing, but surprisingly strong. Clarinets and oboes may not be as penetrating as the instruments we know now, but there is so much character - as in the sinister cackling of the Scherzo.

But as the performance unfolded, it became clearer that we were listening to a fine interpretation. The slow movement has a strange variation in which the theme is transformed into a stiff rococo minuet, then an increasingly fast and crazy march, only to be brought to a sudden stop by hymn-like horns. It can sound bizarre; here it was like a mother warmly but authoritatively silencing a hyperactive child. The spacious, quiet string passage that follows was meltingly beautiful. It was a perfect preparation for the finale, a child's vision of "Life in Heaven", or for soprano Eileen Hulse's fine singing: childlike, and - as Mahler insists in one of the many footnotes - "completely without parody". It was never oversweet; just the radiance and pathos of the happily dreaming child.