The week in radio: Live and dangerously breathtaking

There's a sad little rhyme about an innocent film-goer in the 1940s: "She didn't care much for the brave and the strong - less still for the burning kiss. But she'd sit in the cinema all day long, in the hope that the character beating the gong would miss." At the Albert Hall I once saw the character bashing the tubular bells miss, during an exposed passage towards the end of Berlioz's Symphonie Fantastique. My guilty glee was soon replaced by a sense of awe that everybody else was getting it right.

You can't beat live music. It's the exhilarating sense of risk that is missing from studio recordings. However sublime a sonata on CD may be, you can be certain that there isn't the slightest chance you'll hear a bum note: the tension of the concert-hall is gone.

Although this theory lies behind a large proportion of the BBC budget, the radio, of course, can never be truly live. If you were bowling down the motorway or chopping carrots in your kitchen, you couldn't have been simultaneously at the Glasgow City Hall, watching the BBC Scottish Symphony Orchestra embark on the first of Nielsen's six symphonies. But you could still experience much of the excitement and danger of that live performance, on air, even though it had been recorded a day or two before being broadcast. As part of Nicholas Kenyon's grand three-year project, Sounding the Century, this concert went out on Monday in the Performance on 3 slot - and it raced through the attentive nerves, like an electric current.

In 1901, Carl Nielsen was 27, and so obsessed with Beethoven's Fifth Symphony that he wrote it all out from memory, fully scored. Nielsen's own first effort in the genre, said Stephen Johnson, "reminds you of someone who's just rushed through a hedge and is shaking himself". And so it was - exuberant, young, triumphant. And then came Cristina Ortiz playing Rachmaninov's famous Second Piano Concerto, composed in the same year. Her interpretation was deeper and less restrained than could be glimpsed in a brief encounter - the notes spilling out, sometimes inaccurately, but at such a speed and with such passion that it left me gasping, having forgotten to breathe.

A different, mellower kind of excitement emanated from the 100 Club when Humphrey Lyttelton and his band played there for Jazz Notes (R3) later that night. Humph is a national treasure. The deadpan world-weariness of his chairmanship of I'm Sorry I Haven't a Clue is probably the single funniest element of the only unmissable R4 panel game, ever. But his first love was the jazz trumpet, and he has been 50 years a band-leader. You could hear the ease and familiarity of his players' interaction and enjoy the deliciously riotous and unconfined excesses of their solos - particularly when the great septuagenarian Kathy Stobart let rip on the tenor sax in a very cheerful version of "Tea for Two". Every item in the programme had been composed or arranged by Humph. Typically, he dismissed this achievement, saying that he'd written and recorded about 200 tracks, of which 199 had sunk without trace.

R3 has recently developed its jazz coverage, with Jazz Notes going out four nights a week and Saturday's Jazz Record Requests extended to an hour. This latter is an excellent series, hosted by the genial and extraordinarily knowledgeable Geoffrey Smith. His distinctive "Hello" - as if he's both surprised and delighted you're there - is becoming as established a vocal signature as Alistair Cooke's eternally reassuring "Good morning" - or, if you listen on Fridays, "Good evening".

Elsewhere on the airwaves, the talk has been of relationships. First Nights (R4) followed an engaged couple down the aisle and into a four- poster bed - in the very Cardiff hotel used once (gasp) by Tony Blair. The point of this was that Luke and Sarah had decided on a radical policy of marriage before sex. "People say, oh, wow, how could you do that? I wouldn't be able to," said Sarah. When the history of our century is written, such remarks will show just how far we've advanced. A curious mix of coyness and prurience, this mini-documentary proved little. The post-coital question "What was it like?" wasn't - quite - asked, but the happy couple volunteered the information that it had been very nice to wake up with each other.

A little further down the line, the fine novelist Tim Parks read from his new collection of essays Adultery and Other Diversions (R3). The first followed the collapse of a friend's marriage after the husband's initial, casual affair. It was a sorry story, told with thoughtful insight. In our organised world of automatic gates and comprehensive insurance, said Parks, divorce remains one of the few catastrophes we can reasonably expect to provoke. He saw serial adultery as tangled up with the fear of mortality, a desperate attempt to regain the exuberant enthusiasm that had led to marriage in the first place.

His advice, when you hear the siren song of temptation, is to sandbag the doors and, a little surprisingly, to take up cricket. Still, as quoted in Russell Davies's sparkling new series Cole Porter: Night and Day (R2), "When every night the set that's smart/ Is intruding on nudist parties, anything goes".

R2 has been trying to help, with its latest Social Action Project, Building Bridges. Terry Wogan had the Rev Matthew Reed in his Pause for Thought, who suggested that a successful marriage was like making sure a car was serviced. Meanwhile, everyone was dropping in with advice. Claire Rayner and her husband were particularly baffling. In the space of 25 seconds they spoke of their own rules and then said you have to have rows - and then that there are absolutely no rules. Thanks. I preferred another couple who ended an argument when she spun round from the freezer and hurled some fish across the room: it gave, she said, a whole new meaning to battered cod.