U.S. ad spending declined 2 percent in the third quarter, due to the economic recession and falling consumer confidence, which forces companies to cut back more marketing budgets in newspapers, magazines and radio, Bloomberg reported Thursday.

Cutbacks impacted national spot radio spending the most, which plummeted 18 percent, according to Jon Swallen, senior vice president of research at TNS Media Intelligence. Spanish-language newspapers and local newspapers also dropped 17 percent and 16 percent, respectively.

Third-quarter ads marked a slight drop of 3.7 percent in the previous quarter, thanks to outlays for the Olympics and election campaigns, Swallen said in an interview.

"Ad spending is getting softer, the rate of decline is getting steeper, and those declines are spreading across a broader cross-section of the ad economy. It's not just a newspaper problem or just a radio problem or just a TV problem," Swallen added, according to Bloomberg.

Outdoor advertising decreased 4.6 percent. Even the ad growth of online display slowed down to 5.2 percent from 7.6 percent in the second quarter.

"The growth rates are easing. It's not inconceivable that Internet could flip to a red number," Swallen said, according to Bloomberg.