The outlook for digital switchover for U.K. radio in 2015 has taken a blow with the latest audience research figures.

Digital Radio U.K., the trade body established by the publicly funded BBC, digital network owner Arqiva and the commercial radio sector to drive take-up of digital, hailed the latest results for the fourth quarter of 2009 from RAJAR (Radio Joint Audience Research).

But the numbers are not that encouraging. The share of radio listening hours via a digital platform did increase by 14% from 18.3% to 20.9% year-on-year, but fell from the previous quarter's digital share of 21.1%.

That 14% increase of digital share for Q4 was also partly down to a decline in listening hours for analog: the total listening hours for all radio fell 3% year-on-year to 987.6 million hours a week, while total listening hours for digital were up 11% to 206.3 million.

A successful digital switchover would benefit the U.K. commercial radio sector, as it would no longer have to pay for licenses for analog and digital. Dual broadcasting costs the radio industry £30 million ($46.9 million) a year according to Andrew Harrison, chief executive of trade body RadioCentre. Commercial radio revenues are also down 10% year-on-year to £500 million ($781.4 million), Harrison said last month.

But the government had proposed that 50% of all radio listening hours have to be digital by the end of 2013 to trigger the switchover from analog to digital in 2015. That leaves the industry with a mountain to climb, which explains why there has been discussion about replicating the U.K. government's car scrappage scheme for radio. Under such a system, consumers might get 20% off the price of a digital DAB set if they trade in their old analog radio.

DAB (Digital Audio Broadcasting) sets are leading the way for digital, with DAB's share of overall radio listening hours increasing from 11.4% (116 million hours) to 13.7% (136 million hours) year-on-year. There was also a slight increase from 13.3% (134 million hours) in the previous quarter.

But while the number of adults living in a household with a DAB receiver has increased by 13% year-on-year to 17.1m from 15.1m - with 500,000 of those added in the last three months - listening to DAB in terms of the weekly audience reach has fallen slightly.

The DAB audience reach was 20.4% (10.46 million) of the total measurable population in Q4 2009, down from 20.5% (10.51 million) the previous quarter.

However, DAB was up 8% year-on-year from an 18.9% (9.7 million) audience reach in Q4 2008. The weekly reach figure is the number of people aged 15-plus who listened to a radio station for at least five minutes in the course of an average week during the quarter.

Listening to radio via all digital platforms was up year-on-year in terms of share of radio hours (see above) and the audience reach - an increase of 5% year-on-year from 32.2% (16.4 million) to 33.4% (17.1 million). But there was a noticeable decline from the previous quarter's audience reach of 34.5% (17.7 million).

The BBC is currently reviewing all its digital TV and radio services and any closure of its DAB services could hinder further take-up of digital radio.

Even before any decision has been made, that review has prompted a campaign to 'save' digital-only modern rock station BBC 6 Music, launched in 2002, which has 695,000 listeners as measured by audience reach according to RAJAR. A Facebook campaign to keep the network has 19,700 members.

Ford Ennals, chief executive of Digital Radio U.K., welcomed the growth for digital but said that the future rests on the government's Digital Economy Bill, which has a framework for switchover including automatic renewals of local and national licenses to those services with a digital offering.

"Whilst these figures are a platform for strong growth in 2010, the radio industry has made it clear that without significant change we will not see the step change in listening habits needed to fully deliver the benefits of digital," he said in a statement.

"The Digital Economy Bill is an essential first step in making this happen and we are now working on plans to improve coverage, get digital radios in more cars, work with broadcasters to deliver more exciting content and services, and develop integrated consumer communication campaigns to raise awareness and understanding of digital radio. Only by making these changes will we see a rapid move to digital."