Peter James Hollens (Born March 4, 1980) is an acappella musician from Eugene, Oregon, U.S. He is well-known for his acappella covers, such as Rihanna's What's My Name? / Only Girl and Katy Perry's Firework, which were released in 2011. He is a graduate of the University of Oregon where he earned a Bachelor of Music in Voice Performance. During his collegiate years he co-founded UO's premier men's a cappella group “On the Rocks” and most recently appeared with the group on NBC's The Sing-Off.