Voters in Iowa and other swing states have been besieged with TV ads that only grow more frequent as Election Day approaches. Presidential campaigns, Super PACs, and Congressional candidates have filled the airwaves for months, recently joined by campaigns for state legislative seats and Supreme Court judicial retention.

It hasn’t been unusual the last few days that most every local commercial spot on a TV show has been bought by a campaign. Nationally, Ad Age magazine estimates campaign spending could hit as high as $9.8 billion this year, with much of that in TV advertising. To put that in perspective, the value of Iowa’s soybean crop in 2011 was $5.5 billion, according to the state Department of Agriculture.

More than $30 million in television advertising had been purchased on TV stations serving Iowa markets just through September. But at what point does it all become noise, when the message gets drowned out and viewers can’t tell one candidate from another?

John Murry, a professor of marketing at the University of Iowa’s Tippie College of Business, says that for many viewers, the ads likely are noise and the only attention they pay is to get mad about it. But the ads likely will have an effect on a small number of viewers who are still undecided even at this late date, and despite the relatively tiny size of that group, it’s hugely important because the election could be in its hands.

“The ads have an effect on a smaller and smaller percentage of potential voters,” Murry says. “But the election results will likely be determined by a few thousand votes in five or six states, so the value of these individual votes sky rockets.”

Murry points out that normal advertising campaign rules do not apply to political ad campaigns. Coca Cola, for instance, would never buy up entire ad blocks and bombard viewers with commercials until they’re sick of it. Normal metrics, such as cost-per-thousand viewers, are irrelevant since wasted money on exposures to committed voters—many of whom have already cast their ballot in early voting—are part of the price for reaching the few undecided voters who will determine the election result, he says.

The winner take all nature of an election campaign also sets it apart from a typical marketing campaign initiated by Coke, a company that will be around and wants to persuade consumers to buy its products for a long time. For campaigns, the “company” pretty much goes out of business on Election Day.

“Each presidential campaign has committed around $1 billion to their candidate winning,” Murry says. “Therefore, they are probably more worried about the $1 billion being wasted and their candidate not winning rather than the value of donors money that does not need to be returned.”

The ads likely also serve a purpose in shoring up each party’s base of supporters and motivates them to get out and vote.