That jump reflects in part a rise by 26 percentage points in the number of Americans with access to the Internet. But it also speaks to the increasing ubiquity of smartphones, which have brought media into what were once silent spaces.

“This morning, a colleague in the cab with me spent 20 minutes checking e-mail and listening to things online,” said Tom Webster, an executive at Arbitron, the company that measures radio ratings. “These are times and places where media were not consumable before.”

The telephone survey of 2,020 people also found that those who watch a lot of television — more than 8 1/2 hours a day — skewed older than the population at large, while those who used the Internet often tended to be younger. (Some of those Internet users, of course, are watching television content online.)

Arbitron conducted the study with Edison Media Research, a polling firm and radio market researcher.