According to "Idol Gives Back" producer Simon Fuller, viewers will have to tune in to tonight’s  charity special to see a surprise announcement from Bill and Melinda Gates, reports the Associated Press. 

"[The Gates’] have done something very special, quite incredible, this year," Fuller said in the article. The TV special will air on Wednesday, April 21, from 8:00-10:00 p.m. EST, and the headliners include Sir Elton John, Alicia Keys, Justin Bieber, the Black Eyed Peas and other big name musical acts.

Cecile Frot-Coutaz, CEO of series producer FremantleMedia North America and an executive producer on "Idol Gives Back," explained that U.S. charities will be receiving more of the contributions this year because of the rough economic times. "It’s a very, very tough couple of years in this country and it’s only fair that we focus on U.S. causes as well as some big international causes," she said in a teleconference call, according to the article.