Commercial studios have been the mainstay of recorded music for decades. But what happens when the very foundations of the music business are shaken to the core? How are studios surviving in the face of streaming music, slumping sales, and cheaper, easily accessible recording technology? “Gateway Sound” explores how engineers, musicians, and music-industry veterans are redefining what a recording studio can be. Although the film prominently features key players on the St. Louis recording scene — such as Smith/Lee Productions — “Gateway Sound” provides a much wider perspective, including interviews with legendary producers Steve Albini, Steve Lillywhite, and Vance Powell and performers Richard Fortus (Pale Divine, Guns N’ Roses) and Kristeen Young.