If you watch one of Alfred Hitchcock's better movies (The Birds and The Man Who Knew Too Much are good examples), the timing and pace has a strange effect. The first half hour passes pleasantly enough: you meet the characters, and nothing too much happens. An hour in, and the action is running at break-neck pace, your pulse is racing, and your brain is straining to keep up. What's not clear, and is the magic of Hitchcock's art, is how you got from one state of mind to the other.

In the 10th Symphony, and particularly the slow first and last movements, Mahler does a pretty good job of producing the same effect. It's the scale and ambition of the work that's impressive: the first movement takes just under half an hour, and Mahler has the confidence that he can keep the audience with him as he starts from a calming, gentle theme played by the violas and meanders around a series of variations, ratcheting up the tension ever so slightly at each point until he reaches a thunderous, discordant climax, followed by a gradual release. After three faster, shorter and more cheerful movements, a repeated figure on military drum hits the listener like a rifle shot, paving the way for another long, slow movement, gradually reworking its themes until a resolution of immense power and satisfaction.

It's in the last movement that Mahler shows his own mastery of suspense, and in particular the use of the suspended chord. If you're not used to the idea, listen to the theme of the ersatz Albinoni Adagio shown on the right. Here's the trick: your ear expects the sixth note in the descending scale to go down a semitone to fit into the G minor - D major chord sequence: instead, the composer repeats the fifth note (shown in red, and forming a "D suspended fourth" chord), making you wait for a couple of beats before dropping the note into the F# (shown in green) of the D major chord that your ear is waiting for. Mahler had made heavy use of the suspension technique in the famous Adagietto for harp and strings in his fifth symphony: in the finale of the 10th, he uses it on a truly heroic scale. The best part of 20 minutes is spent setting your ears up to expect that final F# major chord, and Mahler drags the music and chord progressions hither and thither, while, all the time, you keep that F# in your head as you await the final, joyous resolution.

The pitfall in all this is that it's very difficult for a conductor to get the full effect, and in this area, Riccardo Chailly and the Gewandhaus Orchestra were phenomenal at last night's Prom. Mahler's orchestrations are so detailed and intricate that in lesser hands, his music can degenerate into a muddle. In last night's performance, the music was played with absolute clarity: even in the most complicated parts of the scherzi, the several themes being played against each other by different parts of the orchestra came across strongly and with lucidity - quite a feat in the far-less-than-perfect acoustics of the Royal Albert Hall. This is also a tribute to the skill of the musicologist Deryck Cooke, who created the "performing version" of the symphony from the incomplete and scattered manuscripts that Mahler left at his death.

This is not music for a novice. It demands your full attention for over an hour, and requires you to have listened to enough symphonic (and preferably romantic) music over the years that your ears are trained to expect the patterns that Mahler manipulates so subtly. But if you have the patience to stay with it, the experience is all the more rewarding.

David Karlin
8th September 2009