A new study from eMarketer on mobile device usage also shows that radio is currently the third most-popular U.S. media option, behind TV and the Internet. However, radio has lost ground in recent years, as mobile device access has gained in popular to become the fourth biggest option.

Looking at average time spent per day with major media options, TV is ranked #1 with 278 minutes/day, followed by Internet with 173 minutes/day. Radio is at 92 minutes/day, but this is down from 94 minutes just a year ago, 96 minutes in 2010 and 98 minutes in 2009. Mobile is at 82 minutes/day, up from 54 minutes last year and way up from 22 minutes per day in 2009. Print is ranked fifth.

Going by share of average time spent per day with media options vs. U.S. ad share spending, radio is still ranked third. Radio has a 13.2 percent share of time spent per day, with a 9.3 percent of the U.S. ad share. These percentages have also slightly declined over the last four years, down from a 15.5 percent time spent share in 2009, and a 9.7 percent share of U.S. ad spending.

The eMarketer study focuses on mobile device growth, which is projected to grow 51.9 percent to average at 82 minutes/day. The complete study can be found here.