Via the KBS World Sounds of Korea program I discovered the gugak a cappella group from Korea today. From the program web page:

A gugak band named Toris토리스 was formed to bring all these different tori pieces from various regions and make music that can be enjoyed by everyone. Toris is also the only gugak a cappella group in Korea. The group, formed in 2009, is comprised of vocalists specializing in pansori, Korean folk songs, and a cappella. Let’s begin this week’s episode with Toris singing “Saetaryeong새타령” or “Bird Song,” a folk song from the southern region.