As you'll find in the other Industries articles on this site, the radio industry is well-served by a strong association that issues numerous reports bearing the general message that "the rumors of my death are premature."
1. The Radio Advertising Bureau
The most important industry association for radio is the Radio Advertising Bureau (RAB), whose mission is to "lead industry initiatives and provide organizational, educational, research and advocacy programs and services that benefit the RAB membership and the radio industry as a whole." A number of reports and datasheets are linked from this page.
2. Arbitron's Radio Today 2007 Edition
Arbitron's Radio Today 2007 Edition provides truly "an in-depth look at radio listening nationally and by individual formats. Radio Today combines Scarborough consumer data with Arbitron audience data to develop a comprehensive profile of radio listening across America. With information on the purchasing plans and leisure activities for 17 specific formats, the study provides valuable insight on the evolving relationship between radio and its diverse listener base."
3. The Audio Publishers Association
This is the trade group for audiobook publishing and marketing. As detailed on its site:
"In 1987 the Audio Publishers Association (APA), a not-for-profit trade association, was created to:
* Advocate high production value and advise on industry-specific technical standards;
* Serve as a networking, educational and information forum for its members;
* Deliver programs and services that serve the common business interests for its members; and
* Promote policies and activities that accelerate audiobook industry growth."
According to the latest available figures from the APA, in 2006 audiobook sales grew by 6 percent over 2005. Audiobook sales are now estimated at $923 million per year. (It's interesting to compare that sales figure with the mere $32 million in eBook sales recorded in 2007.)