The stronger growth at BBC stations has made the possibility of commercial radio capturing a 50 per cent share of listening in the near future remote.
Its share of listening declined from 46 per cent a year ago to 45.5 per cent by the end of March.
However, despite this setback, the Radio Advertising Bureau is remaining positive. It points out that time spent listening to commercial radio has increased by 4.5 per cent to 496 million listening hours each week.
It also said that commercial radio has a share of 60 per cent of listening among 15- to 44-year-olds, the key target market for commercial stations.
There were some notable success stories in the commercial sector, with Classic FM continuing its rapid growth by adding 800,000 listeners to go to 6.8 million. Its total listening hours were up by just under five million to 50.2 million, a share of 4.6 per cent. Kelvin MacKenzie, the chief executive of The Wireless Group, who has attacked the Rajar system consistently in recent weeks, may be having second thoughts about the wisdom of his attacks as the Rajar methodology showed talkSPORT increased its listening hours by more than one million and built its reach by 10 per cent to 2.47 million.
Virgin's national AM station lost 5 per cent of its weekly reach. It now has 2.47 million listeners, giving it a 1.3 per cent share. Teamtalk 252, which took over the Atlantic 252 licence, suffered a bad first set of results by losing 61 per cent of Atlantic's audience. It now has a reach of just 428,000.
In London, the battle for young listeners intensified with Kiss FM increasing its lead in the 15- to 24-year-old market with an 18.8 per cent share.
Capital's London licence suffered a fall in reach of 130,000 listeners to 2.7 million. However, its listening hours increased by nearly one million to 23.3 million. Its Xfm station saw its reach slip by 5 per cent to 441,000.
Its total listening hours were down 10 per cent to 2.8 million.
Heart 106.2 achieved an increase in listening hours of close to 20 per cent and attracted 116,000 new listeners. Jazz FM, the subject of a potential takeover by Guardian Media Group, saw a spectacular increase of 48 per cent in listening hours and increased reach to 1.1 million listeners.
Justin Sampson, the RAB's managing director, said: "Radio is doing really well and commercial radio is growing and doing well with 15- to 24-year-olds. Most people in commercial radio are happy and the medium continues to provide good opportunities for advertisers."