STEVE INSKEEP, HOST:
Now that Isaac has passed by Tampa, the Republican National Convention gets underway today, but voters living in swing sates have already heard plenty of messages from both political parties - unprecedented waves of ads.
NPR's Steve Henn reports there is an app - an application that can help you figure out who's behind them.
STEVE HENN, BYLINE: If this is what your TV sounds like...
(SOUNDBITE OF AD)
(SOUNDBITE OF MUSIC)
ANNOUNCER #1: Two wars. Tax cuts for millionaires. Death.
ANNOUNCER #2: Mitt Romney turned around dozens of American companies and helped create...
ANNOUNCER #3: Romney would pay only 1 percent...
HENN: ...you might be wondering whose paying for this.
Tom Lee at the Sunlight Foundation says his group's new app - Ad Hawk can answer that.
TOM LEE: Well, it's an idea that they've been kicking around here and there for a while. A lot of us use Shazam and apps like it.
HENN: Shazam is a popular smart phone app that can listen to and identify songs. Ad Hawk - spelled like the bird - works the same way. You fire it up and you'll see a button that looks like a TV.
LEE: As a political ad plays, you hit that, record a snippet of audio and it will match that against our database of thousands of political ads.
HENN: And then, Ad Hawk can tell you more details about the group that's paying for the ad - like how much it's spending or who's backing it.
Of course, groups set up as, quote, "social welfare organizations," are not required to make their donors public. So in those cases, the ultimate source of money may remain a mystery.
Steve Henn, NPR News, Silicon Valley. Transcript provided by NPR, Copyright National Public Radio.