text: It is the radio format that has delivered the latest chart hits, news and talk shows in stereo to homes around the world for decades. But now the characteristic hiss of interference that accompanies most FM broadcasts is set to fall silent. Norway has announced that it will be the the first country in the world to switch off its FM radio signal. Twiddling the knobs of a radio will no longer be necessary  as analogue services switch off in favour of digital . The Norwegian Government said it will turn off its FM transmitters on January 11 2017. Now with the ever expanding number of digital radio services and growing numbers of people choosing to listen to internet radio, it seems likely other countries will follow Norway's example. The UK had planned to switch off its own FM service by 2018 but the plans were later shelved following objections from commercial radio stations. It is now not expected to happen until sometime after 2020 when digital listeners are expected to outstrip those using analogue stations. Streaming has topped CD sales in revenue for the first time in the United States as music listeners flock to on-demand services and Internet radio, industry figures showed. Data for 2014 showed a major shift to streaming as opposed to physical sales and permanent downloads, with rapid growth both for on-demand services such as Spotify and Rhapsody and Internet radio providers such as Pandora. Streaming revenue totaled $1.87 billion, edging out the $1.85 billion earned by CD sales, according to data of the Recording Industry Association of America. Streaming helped stabilize the bottom line for the long-troubled industry, with overall revenue from recorded music going up two percent to $4.86 billion to mark the fourth year of growth. Listening figures currently show that digital radios account for 37.9% of all listening hours in the UK. In the US, around 85% of American adults still listen to AM/FM stations. Norway, however, has just five national FM broadcasting outlets while there are 22 national digital radio stations. The Norwegian government said there was space for a further 20 digital radio stations and NRK, Norway's public service broadcaster, will be the first to switch off its FM service. The Norwegian Ministry of Culture estimates that the switch to digital radio could save £17 million a year (NOK 200 million). Thorhild Widvey, the country's minister of culture, said: 'Radio digitisation will open the door to a far greater range of radio channels, benefiting listeners across the country. 'Listeners will have access to more diverse and pluralistic radio content, and enjoy better sound quality and new functionality. 'Digitisation will also greatly improve the emergency preparedness system, facilitate increased competition and offer new opportunities for innovation and development. Digital radios, like  above, might look retro but can give listeners access to more stations than ever before . Growing numbers of car stereos now come with digital radio as standard, leading to a drop in FM listeners . 'More than half the population already has access to local radio on DAB, and there is considerable potential for further local channels.' The switch off of FM services could create other problems - leaving millions of households with legacy electronics unable to pick up a signal. FM radio, which was first invented in 1933, transmits information by modulating the frequency of the carrier wave. This produces a high quality analogue signal that travels over short distances but can be prone to interference. FM radio became the popular way to transmit stereo broadcasts and it also became hugely popular with pirate radio stations. Digital radio by comparison uses digital modulation - compressing the audio signal into a specific bandwidth spectrum. This allows more radio stations to be crammed into the bandwidth space and can produce clearer reception.
target: Norway will be the first country in the world to stop radio broadcasts on FM .
  It says it will save £17 million a year by the switch to a purely digital service .
  The decision was driven by rise in popularity of digital and internet radio .
  Other countries are expected to follow as numbers of FM listener drop .