The U.S. Internet radio audience has grown 50% over the past year, evinced by the fact that an estimated 12% of the population (about 30 million people) reported having listened in the past week — up from 8% in 2005 — according to a report from Arbitron and Edison Media Research. The study also found that nearly 20% of 18-34 year-olds listened to Internet radio in the past week. “Consumers are quickly embracing radio’s digital platforms and this new research reveals that these advertising vehicles are becoming increasingly viable,” said Bill Rose, senior vice president of marketing for Arbitron.