Tripled earnings sure has a nice ring, and that's what radio broadcaster Clear Channel (NYSE:CCU) posted in its third quarter. However, news agencies were quick to point out that the rockin' numbers were linked to onetime investment gains.

Including $686 million in pre-tax gains due to sale of shares of Spanish-language media company Univision (NYSE:UVN), Clear Channel reported earnings of $1.03 a share, or $636 million, compared to $212.5 million, or $0.34 cents per share, in the same quarter last year.

Without the onetime gains, Clear Channel's earnings were $0.38 per share, missing analysts' estimates by a penny.

So what's the static? Perhaps it's the radio angle. Clear Channel is king of radio, with 1,200 stations across the nation. One piece of Tuesday's news was that advertising revenues were weak in its radio segment -- in fact, flat compared to last year.

Let's think about radio for a minute. As Fool Tom Jacobs (TMF Tom9) pointed out in his commentary on satellite radio, a market niche for satellite radio has been created by the impression that companies such as Clear Channel force-feed redundant, cookie-cutter content. Listeners are left craving music and talk suited to their own tastes and interests.

That is the niche rapidly being filled by XM Satellite Radio (NASDAQ:XMSR) -- of which Clear Channel owns a small stake -- and Sirius Satellite Radio (NASDAQ:SIRI). Both companies are narrowing their losses and increasing subscribers. XM Satellite has already hit the 1 million subscriber mark. Standard AM/FM is bound to lose listeners to this and other encroaching trends.

Though television networks continue to command top advertising dollars while coexisting with premium cable content, radio is different. Music is an individualized media, and many people identify with their music, much of which never shows up on traditional radio. From widespread pirating to the popularity of streaming independent radio stations over broadband, it's clear that the consumer has been waiting for more than the one-size-fits-all content AM/FM radio has been offering.

Admittedly, advertising is still emerging from a slump, though some media companies have reported signs of recovery. However, when it comes to radio-station operators like Clear Channel, advertisers might suspect that listeners have more and more reasons to tune out.

Alyce Lomax welcomes your feedback at alomax@fool.com.