Local revenues were up 1.2% to almost £40.4m, but national revenues fared best, increasing by 3.4% year on year to more than £85m. However, branded content, including sponsorship and promotions, fell £2m year on year, but increased by £1.9m over the first quarter.
The figures for April-June 2007 indicate a steady increase in radio revenues since Q2 2006, when they stood at £148.2m, but they have yet to recover to the level of the all-time high of £168.4m, achieved in the final quarter of 2003.
Simon Redican, managing director of the RAB, claimed the results were "extremely encouraging" and showed the organisation was right to be optimistic in recent months.
"Radio is the multiplier of the digital age and advertisers are recognising the important role it is playing as part of the media mix," he said.
September will mark a year since Andrew Harrison joined as chief executive of the RadioCentre, an over-arching body designed to help turn around falling revenues.
Optimism in the radio sector is high, with the recent entry of Global Radio and Channel 4, while the RAB prepares to roll out its Advertising Effectiveness Tracker, aimed at demonstrating the value of investment in radio to advertisers.