The media company is Arbitron’s largest customer and accounted for 19% of the ratings firm’s revenue in 2009. The new deal will run from January 2011 to the end of 2016 and covers all of Clear Channel’s markets

Clear Channel ditched Arbitron’s system in favour of Nielsen’s radio ratings service in 17 local markets two years ago, in a move that Arbitron’s former boss Steve Morris said would cost the firm $10m on an annualised basis. It is not clear whether the Nielsen deal is affected by today’s announcement.

John Hogan, Clear Channel’s president and CEO, said: “In today’s competitive media environment, advertisers and agencies increasingly demand accurate and timely data to inform their buying decisions. Arbitron’s PPM and diary ratings validate the great power of our medium and our platforms – and help us demonstrate every day how well we deliver on radio’s unique ability to engage audiences.”

Hogan’s words are in stark contrast to five years ago when, leading a search to find a “state of the art” replacement to Arbitron’s diary-based ratings, he said: “Radio is a powerful, effective medium whose influence and reach have been under-reported and diluted.”

Despite resisting at first, Clear Channel agreed a deal for PPM ratings in June 2007. It also signed a three-year deal for diary ratings in 105 local markets (excluding the 17 Nielsen markets) in May last year. Both agreements were due to expire at the end of 2011.

Arbitron CEO William Kerr (pictured) said this week: “We’re gratified that Clear Channel Radio, our largest client, has ensured its continued access to Arbitron services by renewing our partnership on this long term basis.”