The firm is now expecting revenue of $376.2m?$390.9m for the full year (up 2?6% on 2008 ), rather than the $390.9m?$405.7m it had previously been expecting.

However, profit for the quarter ended 30 June was up to $3.5m from $600,000 in the same period last year.

Chief financial officer Sean Creamer said that, in light of reduced revenue visibility, the firm had taken “difficult yet appropriate” steps to rationalise its cost structure and suit the uncertain environment.

During the period Arbitron has announced plans to use its portable people meter to provide out-of-home TV ratings, while facing investigations from the Federal Communications Commission and a Congressional committee into allegations that the PPM system unfairly undercounts ethnic minorities audiences, hurting the ad revenues of some broadcasters.

Creamer told analysts today: “We can’t predict how long these discussions continue or how much it will cost to prepare for and participate in any further litigation or government interactions, or the outcome of these discussions. We do know that these are matters that we want to resolve favourably for our customers, the radio industry and our shareholders. We believe we’re committing the time, energy and resources to do that responsibly.”

Spanish-language radio station owner Univision has said it will not renew its contract for PPM ratings in certain markets, and will not encode its broadcasts for PPM – meaning Arbitron will be unable to measure audiences for its stations.