This is Sample Size, our weekly new music feature with KOSU's Ryan LaCroix and LOOKatOKC music critic Matt Carney.
Today, Matt gives NPR Music's Austin 100 SXSW app a spin and discovers Texas rockers Purple, Los Angeles pop band The Heirs, and 21-year-old Minnesota musician John Mark Nelson.
Follow Matt & Ryan on Twitter at @mdotcarney and @KOSUryan.
