The Media Column: 'Is Kelvin's portable sex spy the best way to measure radio audiences?'

Kelvin MacKenzie is not short of a bob or two, but when he reaches into his pocket, he does not want his money to go to waste. So when the former Sun editor - now the chairman and chief executive of Talksport radio - doled out a small fortune for the exclusive live radio rights to the England vs Pakistan cricket Test series a few years ago, he eagerly awaited the quarterly listening figures.

When the numbers duly arrived from the audience-measuring body Rajar, they showed that he had attracted few new listeners. MacKenzie's reaction was disbelief. So he commissioned an opinion poll from NOP.

The pollsters had a simple question: if you had listened to the Test match live on the radio, which station had you heard it on? Forty-five per cent of those who reported that they had listened to the matches said they had heard them on the BBC. Which would have been difficult, because the BBC hadn't broadcast a single one of them.

False memory syndrome is not, it would appear, confined to the psychotherapist's couch. It also affects radio-listening. At present, unlike TV viewing figures, which come direct from set-top boxes, radio's audience figures rely on that least hi-tech of inventions: your memory.

Every week, more than 3,000 randomly selected people take part in a giant survey, in which they are asked to recall every time they turned on the radio for more than five minutes, and to record the details by affixing stickers into a special diary. (Their payment: a free Biro and a chance to win £100.) But what if, as MacKenzie suspects, people think they are hearing Radio 5 Live when, in fact, they are tuned in to Talksport? Or they don't remember switching on Classic FM for a few minutes while sticking a meal in the microwave? Or they disregard the 10 minutes of Radio 1 they hear while shopping in Benetton?

There is another way. The audience panel could be asked to wear a device that automatically senses what they are listening to. MacKenzie's favourite is the RadioControl wristwatch (pictured above). The watch is like any other - except that it has a hidden microphone. Every minute, it silently records a four-second audio snapshot. Those sound samples are then downloaded into a computer and matched against the output of every radio station available in the area. If Capital FM is playing the chorus of Justin Timberlake's latest single at 11.06am, and your watch's recording carries it at that time, Capital gets your "vote". The advantage is, of course, that the watch does not forget, tell lies or pretend it is a Stockhausen-loving Radio 3 fan when really it prefers the music from the Old Spice commercial on Classic FM.

Rajar has carried out 15 months of tests on the watch and another monitoring device, known as Arbitron, and a report will be presented to its board within a fortnight. Too slow for MacKenzie, who commissioned his own watch-based research, in competition with Rajar, and revealed his first batch of figures last week.

The winners under the new system are the speech-based stations. Radio 4 jumped to the No 1 slot, up from 10 million listeners a week, with Rajar, to 17.9 million, with the watch. And guess what? Talksport went up from 2.2 million to 8.1 million, making it the biggest commercial station in the country.

You can see why MacKenzie likes the watches. But tell me whether you would agree to wear one of them. He is, in effect, demanding the right to record every minute of your life, whatever you are doing - even if, through no fault of your own, you sometimes go to the loo or (hushed whisper) have sex.

I'd have understood MacKenzie's excitement if he were still editing The Currant Bun. But does he really want his listeners to send him their recordings of themselves as they make love?

MacKenzie concedes that the RadioControl watch does keep tabs on you, whatever you are up to. "It'll record you having sex, yes, but it won't recognise it. There is no substance to any Big Brother fear." He also claims that, in his trials, twice as many people proved willing to wear the watches, requiring minimal effort on their part, as were prepared to fill out Rajar's intricate diaries. Yes, but were they told how they were being spied upon?

The diaries will have to go eventually. I sense that even Rajar realises that. MacKenzie is right to say that there are vested interests trying to keep the old system in place (just as there is a big vested interest in his trying to dump it). But I do not think his portable sex spy is the answer.

v.graff@independent.co.uk