TODAY, Hungarian composer Gyorgy Ligeti is best known for the music accompanying some of the most iconic scenes in Stanley Kubrick's film 2001: A Space Odyssey – otherworldly compositions with names like Atmospheres and Lux Aeterna, the latter a spacey choral piece for 16 voices which Kubrick uses in the scene where suited astronauts inspect a mysterious black monolith under lights in a ghostly lunar landscape.

But Ligeti's journey to cult status and a place at the forefront of the avant-garde music scene of the 1960s and 1970s began with a radio broadcast he heard one day in November 1956. As Hungarian resistance fighters battled Soviet tanks in the streets of Budapest, the 23-year-old composer tuned his dial to some unknown frequency and found himself listening to an extraordinary piece of music. It was called Song Of The Youths and it was made by blending electronically generated tones and pulses with the voice of a 12-year-old boy soprano. It was only 13 minutes long, but it changed the course of Gyorgy Ligeti's life.

The composer of that work was Cologne-based Karlheinz Stockhausen, then in his late 20s and working at German radio station WDR. Having lost most of his family in Nazi concentration camps, Ligeti fled Soviet-occupied Hungary for Germany, where he sought out Stockhausen. He wanted to learn from him, and learn he did, first at WDR – like other forward-thinking European radio networks, including the BBC, it had set up a studio to champion this new electronic music – and later in Hamburg and Vienna. Composers who would in turn be influenced by Ligeti include Brian Eno, Steve Reich and Philip Glass.

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In 1957, the same year Gyorgy Ligeti arrived in Germany, an eight-year-old American boy called Paul Gambaccini was also discovering the power of radio. The sounds emanating from his set were rather less esoteric than the ones powering Ligeti's imagination – the song was Teddy Bear, by Elvis Presley – but the effect was no less energising.

"It was the first time I heard my father swear," Gambaccini recalls in Music In The Air, a six-part history of music radio beginning this week on BBC Radio 2. "'How can you listen to this damned music?' he shouted. 'There has to be something to this rock and roll,' I thought, 'if it affects my normally poised pop like that'."

Everyone has a similar story – a piece of music which has made us stop what we're doing and pay attention. For legendary Sire Records boss Seymour Stein, it was hearing John Peel play Teenage Kicks by Northern Irish band The Undertones twice in succession on his BBC Radio 1 show while Stein was being driven through London by Sire's UK representative, Paul McNally. "Pull over, pull over, stop the car!" he screamed. McNally thought Stein was ill. He wasn't. "I have to sign this band," the American yelled. "They're f***ing amazing". McNally was dispatched immediately to Derry to do the deed.

At 5.33pm this Wednesday – 90 years to the minute since the first BBC radio broadcast – there is the potential for another of these stop-what-you're-doing-and-listen moments as a specially commissioned work is broadcast across every single BBC radio station. It isn't punk, rockabilly or avant-garde electronica, though it draws on the same spirit of boldness, populism and experimentation that made those forms so ear-catching when they first blared out of a radio speaker.

It's called Radio Reunited, and it has been created by Blur and Gorillaz frontman Damon Albarn. Given the role of "curator" to the project, he has created a three-minute soundscape featuring music and snippets from a selection of recorded messages made by listeners on the theme of the future. It will be aired during a special live show from the Science Museum in London, which houses the 2LO radio transmitter which made that first BBC broadcast on November 14, 1922.

"It's a powerful idea," Albarn says of the project. "I love the idea of stations across Britain and the World Service coming together, with all of our different lives and circumstances, even if it's only for a few minutes."

Radio Reunited forms the centrepiece of the BBC At 90 anniversary celebrations, of which Gambaccini's series is also a part. The BBC is calling it "an unprecedented global simulcast" and in a world of iPods and downloads, where the enjoyment of music is said to have become increasingly atomised, Radio Reunited is certainly one in the eye for the cult of the individual – with a potential audience of 120 million across every inhabited continent, and everyone listening at the same time, it doesn't get much more communal than this.

"I think of radio as the most important 20th-century medium," says academic and critic Simon Frith in Settling The Score, a book published a decade ago to accompany the BBC Radio 3 series of the same name. "People are individuals, but always in the context of wanting to be part of something else. Radio, to this day, is a way of feeling part of a broader conversation, a wider community."

In the 21st century, little has changed. For musicians, radio remains an important delivery mechanism to a mass audience. It is a relationship which is as old as recorded music itself. Occasionally, however, musicians have also used radio as an instrument in its own right. It's an idea that wouldn't have seemed alien to early radio listeners, whose wireless sets were deliberately manufactured to resemble the pianos they replaced, even down to being made of wood which was often described as "piano-finished" in the marketing spiel.

For instance, when celebrated avant-garde composer John Cage gave lectures, his piano accompanist David Tudor would "play" several radios situated throughout the room, spinning the dials to catch random bursts of static and snatches of speech. And when Stockhausen found he could use equipment designed for broadcasting to make electronic music in a radio studio, it wasn't much of a stretch to then transmit the music with the machinery at hand.

Of course, it helped that Stockhausen had a sympathetic and supportive boss at WDR, though it has always been the case that radio has proved more amenable to experimentation than television. The lingering effect of BBC founder Lord Reith's statement – "Give the people something better than they think they want" – can still be felt, at least in the outer reaches of the schedules, and it's in that spirit that Albarn's work has been commissioned.

Had The Beatles arrived in Hamburg a few years earlier than they did, they could perhaps have listened to the same broadcast as Ligeti and been similarly inspired. As it was, it was young German photographer Astrid Kirchherr who introduced Paul McCartney to Stockhausen's work; The Beatles would later add the composer to their pantheon of heroes on the cover of 1967 album Sgt Pepper's Lonely Hearts Club Band.

Cage was the greater influence, however. McCartney came across the American's ideas in the mid-1960s at a performance by Cornelius Cardew, who had studied with Cage and had spent two years as Stockhausen's assistant. A disciple of both men, Cardew had an experimental performance group called AMM in which he played piano, cello - and transistor radio. For McCartney, whose own music was ubiquitous on pop music radio at the time, it was another example of how to think differently about sound. Soon, he was experimenting with tape loops.

By then, the BBC had its own electronic music studio up and running and its efforts could be heard across the network. Another strand of the BBC At 90 celebrations is a series called 90 x 90, programmes just a minute and a half long covering every year of broadcasting between 1922 and today. These air daily on BBC Radio 4 Extra from Wednesday.

One from the late 1950s concerns the genesis of the BBC Radiophonic Workshop, best known for creating the theme tune to Doctor Who but also responsible for a range of weird and wonderful sound effects which were used in the radio drama output. Again, speech and sound coming together in new and exciting ways; again, a Beatles connection – in 1962, the same year he met the nascent Fab Four, George Martin teamed up with Radiophonic Workshop luminary Maddalena Fagandini to re-work one of her time signals for the pop charts. It was released as Time Beat under the pseudonym Ray Cathode.

The Radiophonic Workshop was closed in 1998, but in September this year the BBC announced its revival, under the stewardship of experimental musician Matthew Herbert. One of his first commissions was a "sonic memorial" to Bush House, which housed the World Service for 70 years until this summer. Speaking at the time, Herbert said he was hoping to find "engaging answers to some of the modern problems associated with the role of sound and music on the internet, in certain creative forms and within broadcasting". A brief recent blog post says simply: "We are entering the age of sound."

Entering? We never left it. Ninety years on from the BBC's first radio broadcasts and half a century or so after the first forays into electronic composition were beamed across Europe, the power of the medium is undiminished. As Gyorgy Ligeti found, if you turn the dial enough there's a sweet spot on the wavelength somewhere which can bring sounds to make you jump, laugh, cry, think – or stop what we're doing, alter your course and pack your bags for a journey. All you have to do is keep listening.

Music In The Air: A History Of Music Radio, BBC Radio 2, from Tuesday, 10pm; Radio Reunited, all stations, Wednesday, 5.33pm. The 90 x 90 programmes are scheduled across all networks for 11 days from Wednesday but will be available to listen to on the BBC Radio 4 Extra homepage from tomorrow