Are we forever Radio Ga Ga?

For Hollywood star Alan Cumming, the loss of Janice Forsyth from the Saturday morning schedule is one of these times of national emergency. He used that very phrase when tweeting his support for the petition which has been raised in support of her. It now has over 1500 signatures. There are T-shirts too – "Save Janny On The Tranny" is the slogan-of-choice – and even a poem, courtesy of Ian Rankin. Politicians Nicola Sturgeon MSP and Douglas Alexander MP have added their voices to the clamour, as have musicians Edwyn Collins and Alex Kapranos, graphic novelist Mark Millar and crime writer Val McDermid. A live music event is also planned. At this rate, the Forsyth saga will rumble on until July, the proposed switch-off date for the veteran broadcaster.

Surprised at the hysteria? Don't be. It shows the level of devotion a much-loved radio station or programme can instil in its listeners and proves once again that this most intimate of mediums still has tremendous power.

I say once again because this script, in which an unpopular change is met with howls of outrage and an internet campaign, is becoming very familiar. We first saw it aired in February 2010 when news was leaked of BBC director general Mark Thompson's plan to close BBC Radio 6 Music. Thousands of letters and emails were sent to the BBC, more than 180,000 people joined a Facebook campaign and 62,000 signed an online petition. In July 2010, the station was saved when the BBC Trust said it wasn't convinced by Thompson's closure case. A year later, audience figures had doubled.

One of the prime movers in the campaign to save BBC Radio 6 Music was listener Paul Lewis. "They were absolutely, definitely closing the station," he says. "Several times I've met with Tim Davie, head of BBC audio and music, and he has said, 'Don't doubt for a second we were.'"

Since then, Lewis has also helped save Tom Robinson's BBC Radio 6 Music show, Introducing, and been active in the campaign to lessen the effect of cutbacks to the World Service. So could an equally vociferous and high-profile campaign make a difference where Janice Forsyth is concerned? "No question," he says.

If radio audience figures were falling, the cuts, closures and rejigs that people like Lewis rail against might matter less. Broadcasters could dress them up as well-meaning attempts to manage decline. But, in fact, the number of radio listeners is rising, to the point where we have to ask: is radio, rather than television, the medium of the future?

It is starting to look that way. According to Radio Joint Audience Research (RAJAR) figures released this month and covering the last quarter of 2011, 90% of the UK population now listen to radio at some point in any given week. BBC Radio 4 alone gets 10.83 million listeners per week, while BBC Radio Scotland pulls in 959,000. Top of the pile is BBC Radio 2, with 14.27 million listeners.

Meanwhile, RAJAR's year-on-year figures show that the number of people listening online or via digital radios has increased by 10%. And an accompanying survey found that while 11% of over 25-year-olds listened to radio on their mobile phones, the number in the 15 to 24 demographic was almost three times that figure. Teenagers love radio too, it seems – especially now they can download podcasts of their favourite programmes or replay them on the web. It also fits neatly into what marketers call "the cult of free": the belief, firmly held by many young people, that content should incur no cost to the end-user.

"Radio belongs in the digital age in a way that television doesn't," says John Osborne, avid radio listener and the author of Radio Head: Up And Down The Dial Of British Radio. "This is the exciting thing about it: it has been redefined and has really kept up with modern technology but it hasn't sacrificed any of its traditional roots."

Crucially, it hasn't had to sacrifice any quality in its delivery either. Anyone who has tried to watch television on a smartphone or enjoy a film on a tablet –The King's Speech, perhaps? – will know that the experience is diminished because the screen is so small. Radio doesn't have that problem. Its simplicity means the experience of listening to it is relatively unchanged wherever you are. It might come at you through a pair of tomato red Beats by Dr Dre headphones as you sit on a bus. It might come from the speaker of a battery-operated tranny as you drink tea in your mum's kitchen. But it's going to seem more or less the same either way: sound, carried on the air, going into your ear.

But it isn't just ease of access and greater availability via podcasts that has caused us to fall in love with radio again. There's also an increasing awareness that in times of high political drama – during an expenses scandal, say, or a financial crisis – it is news programmes like BBC Radio 4's Today which ask the difficult questions and often provide the best analysis. The latest RAJAR figures back this up. Today now has a weekly audience of 7.15 million, a mere 90,000 short of BBC radio's flagship programme, the Chris Moyles breakfast show, and only a fraction below its highest-ever audience figure.

There's also a feeling among radio industry-watchers that the medium is thriving in part because television has lost its way. "TV is out of control," says Osborne. "It's unrecognisable from 10 years ago, what with the language and the content. It's at the lowest it's ever been, whereas radio is quite proud of being intelligent without being intellectual. It's never declined, that's its secret. That's why people really love it."

Don't think it's only BBC Radio that's winning new listeners, either. Osborne points to Absolute Radio's recruitment of comedians Frank Skinner and Dave Gorman as evidence of a commercial station that's navigating the digital age with great skill. As well as broadcasting, Skinner and Gorman produce podcasts, which in turn drive listeners to Absolute Radio's family of websites. Last year, meanwhile, commercial station talkSPORT won the coveted UK Station of the Year title at the Sony Radio Academy Awards. Launched in 1995 as Talk Radio, it is currently enjoying its highest ever audience figures.

Writer AL Kennedy has penned works for television and radio as well as novels. On Saturday, BBC Radio 3 broadcasts a new drama by her, That I Should Rise. Like Osborne, she takes a dim view of the current state of television and agrees that its shortcomings are among the reasons people are turning back to radio, especially radio drama. But she's considerably more strident in her criticism of the younger, brattier medium.

"Half the programmes on television are sh*t reality shows and the other half are programmes about how they made the sh*t reality shows," she says. "BBC television mimics commercial television which mimics hell. But that doesn't happen on radio."

To her mind, BBC television has debased itself in the chase for ratings. It has stupidly followed the commercial networks down the rabbit hole and aped the reality show formats it found there. More Blunderland than Wonderland, then.

"All of this stuff follows the rules of conversation," she says. "If you're sitting with someone who yells at you and flashes their tits you're probably not that interested – or certainly not consistently interested, if that's all they do. It's dull. Radio isn't doing that. It may not be speaking peace unto nation but it's trying to. The news journalists are interested in news. They don't have to only show you something if they've got pictures. From the point of view of writing drama, you can get movie stars because they have a day off. You can get the best possible people."

That I Should Rise took two days to make, she says, and cost about £7000. Not bad for an hour of high-quality drama featuring veteran actors Tim McInnerny and Dame Harriet Walter. For that reason, she adds, "you still get people like David Hare and Russell T Davies writing for the radio – and why wouldn't they? They can still get things made". Creative, interesting, challenging things, she might add.

Here again, it is radio's three simple ingredients – words, music and sound – that give radio drama its power. In another programme to be broadcast this week – Writing In Three Dimensions: Angela Carter's Love Affair With Radio – critics Susannah Clapp and Robert Giddings talk about the five radio plays the acclaimed novelist wrote in the 1970s and 1980s. They also go to the heart of why radio drama still matters and why writers of all sorts love it so much.

"Writing for radio involves a kind of three-dimensional storytelling so that a great number of things can happen at the same time," says Clapp. "Radio always leaves that magical and enigmatic margin - which must be filled in by the imagination of the listener."

Giddings adds: "It's a wonderful opportunity for writers. There's no other medium quite like it. It renders in terms of the possible what in other forms is impossible. It is free of all the restraints that narrative prose fiction places on a writer."

But we listeners love radio of all flavours. In an age of pay TV, for instance, when millions of pounds change hands for the right to screen football matches on television, radio lets us follow the game for free. It calls our politicians to account by dragging them into radio cars and studios and grilling them while we grill our toast. It sends us music that can stop us in our tracks. And it respects us enough to remember that the human imagination is a mightier engine when it is given room to float. Perhaps, though, we only realise the strength of that love when change comes knocking.

"I did it anonymously at first," says Lewis of his now-famous campaign to save BBC Radio 6 Music. "I wondered: 'Do people care as much about radio as I do? Is Gideon Coe's show at 9pm as important to other people as it is to me?' I didn't even tell my family I was doing it for the first month."

People do care, though. And when Lewis stood up, hundreds of thousands of others stood up too. One of them was Damon Albarn, whose message of support was read out at a protest rally outside BBC Broadcasting House in London.

Albarn also once quipped: "When I die, I want to have Radio 4 piped into my coffin." Janice Forsyth will definitely be off the air by then, reprieve or no reprieve. But one thing's certain: the medium she has served will still crackle with life.

l Books: pages 62 and 63