MUSIC : Time alone will tell

LSO / Sir Colin Davis Barbican Hall, London

The jury is still out on Sir Michael Tippett's The Mask of Time. When a famous artist reaches 90, it's natural that dissenters should tend to keep respectfully silent, at least in print. But this hugely ambitious choral work has its serious detractors - and I'm not talking about the would-be controversialists of the Hecklers band. Writing about Tippett for the Musical Times, Derrick Puffett (on the whole an admirer) describes The Mask of Time as "an almost complete disaster on aesthetic grounds"; and talking to composers, performers and other writers, I've found that the doubters outweigh the out-and-out fans by a fair margin.

Still, it's a critic's duty to approach a work with open ears, no matter how often he or she has heard it. There's always the possibility that one day there will be a performance that shows how wrong you were - as happened for many when Norman del Mar took on Tippett's then neglected Midsummer Marriage in 1963. For about 20 minutes after Sir Colin Davis took up his baton in the Barbican on Sunday evening, I thought this might be just such a performance.

Thanks to singing, playing and musical direction of exceptional strength and conviction, Tippett's musical images not only sprang to life, but merged into something grippingly coherent. The sounds, the colours were wonderfully vivid, the word-setting no less wonderful - the chorus's opening "Sou-ou-ound", glowing and vibrating with brass, bells and electric keyboards, was one of many ideas that went on replaying themselves in the memory after the performance was over.

But then we got to Section 4, "The Ice-cap moves South-North", and what, despite the best efforts of all concerned, still sounds to me like some of the most purely hideous choral writing in all music. It isn't just that Tippett pushes the voices till they shout, or virtually scream; that can be effective, thrilling even - think of the Choral Symphony! I just don't see why he does it - and for page after page. One day, maybe, someone will assemble a complete chorus with perfect pitch and we'll discover what the harmonies mean - though taking the score to the piano hasn't enlightened me yet.

The rest of The Mask of Time continues to swing between brilliant or gorgeous inspiration (that really is the word) and more of this voice- crucifying turgidity. But Davis kept his grip on the reins and steered it magnificently, so that the final tutti rose and swelled like a series of great waves. How on earth did the singers manage to keep back so much for this? Even if you weren't converted, you'd have to admit that it was an astonishing effort all round.

Davis and the LSO did similar heroic work on behalf of Tippett's Fourth Symphony the previous Thursday. There are fewer problems here (though the synthesised "gentle breathing" still jars) and the imagination fires at a more consistently high level - and what an opening, like stepping into a new world! But did the background "birth-to-death" idea quite come off? The intensity and vigour were kept up almost to the end, when suddenly all was sinister quiet chords and the computerised death-rattle. It sounded even less inevitable after Davis's high-tension performance of Sibelius's Seventh, the ultimate in organic, one-movement symphonies. Far better inorganic Tippett, though, than the Japanese violinist Midori's bizarrely romanticised rendition of Stravinsky's Violin Concerto - wonderful playing that completely missed the point.