I'm beginning to think of my iPhone with its free Public Radio Tuner app as my "infinite dial," having just had the experience yesterday morning of an early drive from Baltimore to Washington listening to WSIU in Carbondale, IL by simply plugging my iPhone into my car's sound system. [Hint to pubcasters: WSIU's signal that morning was very reliable and sounded great, but the higher bitrates some stations are using contribute no fidelity that you can detect in a car and have many, many more dropouts.]
However, in this case, it refers to a study of this name from Edison Research and Arbitron:
They say, for example, that an estimated 69 million Americans listened to online radio in the last month and that weekly online listening (42 million) is up by one-third year over year. The same number of people who listen to internet radio in a month watch internet video in a week (69MM). For satellite and HD Radio, there are awareness data only. Finally, in spite of the rapid growth in internet radio listening, 80% of people say yes to, "In the future, you will continue to listen to AM/FM radio as much as you do now, despite increasing advancements in technology?"
A rich study. Link: Edison Research. --Dennis