Clear Channel Radio is rolling out a proprietary system that allows advertisers to more precisely place units against programming content or other ads.

Three advertisers -- Visa, Geico and Walmart -- have tested the technology, which works much like Internet ad insertion systems.

While the practice of placing ads against content isn't new, Clear Channel's new system shortens the lead time for advertisers and provides more precise customization.

"We could do this manually, but this allows us to price a campaign in moments, get the campaign on the air in days, rather than weeks and minimize the risk of errors," said Jeff Howard, president of Clear Channel Radio Sales. "We want to make radio easier to buy. Purchasing radio has been very clunky in the past."

For Geico, Horizon Media placed ads near insertions touting automakers and car dealers. Also factored into the placement were precise daypart requirements to run 15 minutes past the hour during morning drive to emphasize the message: "Since it's now 15 after the hour, there's no better time than now to spend the next 15 minutes saving 15 percent with Geico."

"The ability to place ads in context within a live broadcast significantly increased the value of this Geico campaign," said Lauren Russo, svp and managing director for local audio and promotions for Horizon.

To support Walmart's retail sales contract for AC/DC's Black Ice album, MediaVest and Clear Channel devised a schedule where ads ran immediately following airplay of AC/DC songs. The campaign ran in 91 markets. As a result, Walmart moved 784,000 copies during the first week of release, the second-largest debut week for an album in 2009, per Billboard.

OMD placed Visa ads next to ads for other retail venues where people might not think to use their Visa card. The Visa ads were paired with 25,000-plus merchant messages in more than 120 markets. Visa's network experienced a 10 percent rise in volume compared to the same period the previous year.