Investor’s Business Daily – More Americans are listening to Internet-based radio, according to a study by research firms Arbitron and Edison Media. About 33 mil, or 13%, of Americans age 12 or older listen to a radio station via the Internet on a weekly basis, up from 29 mil, or 11%, a year ago. The study also found a strong link between online radio listening and the use of social networking Web sites. About 63% of online radio listeners age 12 or older have a profile on a social network site, while the rate is just 24% among the general U.S. population.