Sirius XM Radio (SIRI -1.59%) continues to thrive as a premium content provider, but it's not as if the competition's asleep at the wheel.

CC Media's (NASDAQOTH: CCMO) Clear Channel is beefing up the talk content features of its popular iHeartRadio app, adding a directory for the free platform's users to stream more on-demand programming.

When Clear Channel rolled out iHeartRadio, it began as a way for the terrestrial radio giant to stream its 850 stations beyond their local range. The app has gone on to attract hundreds of other stations, and in July we saw Clear Channel introduce iHeartRadio Talk to showcase its non-music content. The appeal of popular if not polarizing talk show icons including Glenn Beck, Sean Hannity, Rush Limbaugh, and Ryan Seacrest became available on the ad-supported streaming app. In a show of faith to the viral nature of user-generated content, chatty users were also invited to submit their own podcasts for inclusion. 

One can expect the visibility of iHeartRadio Talk to continue to grow. This morning, Clear Channel revealed that it will be teaming up with Disney's (DIS -0.83%) ABC to offer segments from The View and Jimmy Kimmel Live to coincide with the new fall season.

In and of itself, this isn't a big deal. Sirius XM had just 18 million subscribers when iHeartRadio was launched as a website five years ago. Despite the platform's evolution into a mobile app with more than 20 million registered users, Sirius XM serves more than 25 million subscribers now. 

However, Clear Channel does point out that 60% of the iHeartRadio Talk usage is coming from mobile devices. In other words, these aren't folks listening at home. A lot of those users may be listening in their cars, and that may come in lieu of satellite radio. 

For now, it doesn't matter. The market for audio continues to expand, and there's plenty of growth for both Sirius XM and iHeartRadio to enjoy. There is no reason for that to end anytime soon. Automakers moved 1.5 million new cars off dealer showrooms last month, and that's great for Sirius XM. The boom in smartphone usage naturally bodes well for Clear Channel's app -- and even Sirius XM's own online initiatives.

Until the market of accessible ears is saturated, everybody can be a winner.

Investors should be aware of the trend and developments, but there's nothing to worry about just yet.