Where have the network television audiences gone? According to Nielsen Media Research, there were 9 percent fewer eyeballs in April and May tuning into shows on ABC, CBS, Fox and NBC than at the same time last year.

If you're a network boss trying to generate excitement about the fall lineup, news of a tumble in audience share couldn't come at a worse time.

"Free" television has always been subsidized by advertisers. Networks charge for commercials based on the number of viewers they can deliver. Some profit is plowed back into the development of new shows that will be used to attract a bigger audience and more advertisers.

The problem today is that even popular shows like "Desperate Housewives," "Grey's Anatomy" and "American Idol" have begun to feel the sting of viewer indifference and changing habits. If "Survivor" isn't immune from declining audience and "CSI: Miami" draws as if it should be renamed "D.O.A.," then things will probably get worse before they get better.

The writers' strike of 2007-08 is only partly responsible for the drop in audience. But the networks' loss has been cable television's gain. Non-network shows like "Mad Men" and "Damages" have benefited from frustrated viewers willing to explore the wider universe of offerings. Cable shows on FX! and AMC have seen their audiences grow.

Without "Lost" or "House" around to reinforce an addiction to network programming, viewers were free to explore social networks on computers, video games and interests completely unrelated to the "idiot box."

Digital video recorders are also more prevalent than they were a year ago. Freed from the tyranny of the network schedule, viewers can watch their favorite programs without regard to the original broadcast time. This undercuts the networks' ability to guarantee an audience of live eyeballs for advertisers.

It could be the end of television as we knew it. The irony is that, just as TV screens are getting bigger, the audience for the networks is going the other way.