The television industry had switched from diary entries to metered ratings in 1987 and had seen similarly surprising changes  young men, for instance, watched cartoons much more heavily than they had reported doing, said Gary Holmes, a spokesman for Nielsen. But it took the radio industry almost two decades to catch up.

Since the 1960s Arbitron, the main radio ratings company, has relied on paper diaries. It currently asks about 800,000 people annually to log a week of listening habits. Problems have been numerous: people’s recollection was imperfect, if they listened to a station briefly they could forget it, and they might overstate listening to stations that they felt reflected better taste.

“People tended to look at it almost like an election  they would vote for the things they liked,” said Jaye Albright, an industry consultant with Albright & O’Malley, a radio consultancy.

In 2007, Arbitron formally introduced the Portable People Meter, a pagerlike device that about 57,000 survey participants carried around all day. After introducing the device in 2007 in two cities, Philadelphia and Houston, last year Arbitron moved it to 12 major areas including New York, Chicago and Los Angeles, added 19 more this year and expects most major markets to be measured by the end of 2010.

“Advertisers were demanding it,” said Alton L. Adams, Arbitron’s chief marketing officer.

Now, with a year of data from the early converts, researchers are finding intriguing patterns. Men had been thought to make up 34.7 percent of the soft-rock audience, according to Arbitron Radio Today 2008, based largely on paper entries. This month, Research Director and the publication Inside Radio released their analysis of meter-only cities from July through October, showing men make up 40.1 percent of the total light-rock audience, a jump of 16 percent. “It caught people by surprise,” said Charlie Sislen, president of Research Director.

“It may be a case where men didn’t want to admit they were listening to a light A.C.,” said Greg Ashlock, president and market manager for Los Angeles at Clear Channel, using industry shorthand for adult contemporary, or soft rock. “ ‘No, I don’t listen to Céline Dion. I’m a sports guy.’ ”

Some male soft-rock listeners say they simply like the music.

Ezra Feinberg, 33, a psychologist in San Francisco, listens to KOIT, a soft-rock station, on his commute. “One in 10 songs on soft-rock radio resonates, but it really resonates,” he said.