The BBC's share dropped from the record 56% it managed last quarter to 54.3%, with Radio 4 and its local stations proving less popular.
Commercial radio reached 32m people per week, and made gains with listeners in both the over 45 age group and with 15- to 44-year-olds. It achieved a 53.7% share among the former group, up from 53.3%, and a 34.8% share among the latter, up from 33.2%.
Andrew Harrison, chief executive of commercial radio's trade body RadioCentre, said: "It is fantastic to see increases across the board for commercial radio. We have consolidated already strong positions among our core and younger audiences this quarter, while also reporting gains among the older demographics."
The listening boost follows tentative signs of a recovery in advertising revenues, which have been in the doldrums for the past two years.
National commercial radio's share of listening rose over the quarter from 10.7% to 11.2%, while local commercial's share rose from 31.4% to 32.3%.
The leading national station, GCap Media's Classic FM, lost 300,000 listeners during the quarter. Its reach is down to 5.7m and its share is down from 4.2% to 4%.
TalkSport's share also fell, from 2% to 1.8%, though the UTV-owned brand's reach was steady at 2.37m.
The third national station, SMG-owned Virgin Radio, which is preparing for a separate stockmarket flotation in the autumn, increased its share from 1.4% to 1.5% and its reach from 2.45m to 2.53m. The reach figure is its highest for three years.
The BBC's national radio offering remained strong, with Radio 2's share at 15.6%, down slightly from 15.8%, and its reach at 13.12m, down by 140,000 listeners.
Radio 4's share dropped from 12.2% to 11.2% but Radio 1's was up from 10.1% to 10.3%. Radio Five live was unchanged at 4.2%.
Back in the commercial sector, Guardian Media Group's expanded Smooth Radio joined the club of big regional networks with a substantial national share.
In mid-March GMG rebranded three Saga stations as Smooth, adding to its two existing Smooth stations. Smooth now has a 2% share of national listening, up from 1.1%, and a reach of 2.29m, up from 1.5m.
Emap's Magic was the leading regional network this quarter, with its share climbing from 2.2% to 2.4% and its reach up from 3.17m to 3.38m.
It just pipped Global Radio's Heart, which grew its share from 2.2% to 2.3% and its reach from 3.09m to 3.25m.
GCap's national digital-only station TheJazz recorded a debut Rajar figure of 334,000 listeners and a 0.2% share. This was higher than other national digital-only stations such as Chill, with 189,00, Core, with 126,000, and Life, with 112,000.