The pair looped their voices for four part harmony

Jimmy Fallon and Billy Joel turned their voices into four part harmony on The Tonight Show Starring Jimmy Fallon Thursday night.

The comedian-singer and Piano Man looped their voices using an iPad to form the two man doo-wop group — singing “The Lion Sleeps Tonight” by The Tokens in four part harmony.

Fallon told Joel, “You’re one of my all-time favorites and just to get to talk to you, I get a little bit nervous. But, to sing with you is the craziest thing, so I came up with an idea where maybe I can sing with you.”

Joel obliged and they even got a little help from The Tonight Show house band, The Roots.

Take a listen:

From the video, it appears Fallon used “Loopy HD,” an iPad and iPhone app that’s available in the App Store for $7.99. The app can be used to “create music by layering looped recordings of singing, beatboxing or playing an instrument with a savvy, sophisticated, tactile new looper that totally reinvents the formula.” It also includes Audiobus support and also features built-in loops.