It was "Video killed the Radio Star". But in the 3rd millennium the internet aims to the lion's share.
Combinations of radio+internet work very good, as they add some plus to the traditional "voice".
But traditional radio suffers from lack of ad-dollars.
"eMarketer estimates that US online ad spending will reach $21.7 billion this year, while radio spending will grow only slightly to $20.4 billion.
Of course, the radio audience is still huge. According to Bridge Ratings, terrestrial radio commands a weekly cumulative audience of nearly 283 million Americans.
Nevertheless, data from a number of researchers indicates that traditional radio is losing its significance in people's lives. US adults are spending more time each day on the Internet and watching TV than listening to the radio."According to researches, Americans consider radio less "essential" than TV and the internet in their life - though not the least essential, as newspapers win the match in this latter case, with a 35% responders.
eMarketer article and figures,
http://www.emarketer.com/Article.aspx?id=1005305