as you may already know by now, these .SNS files are part of EAAudioCore sound system (used only by EA). however .SNS is just "raw sound data file" so it needs a "header file" so it could be played back. "header files" usually go by this .SNR extension.
unfortunately i have very little knowledge of how the game works or even its files but i only know all this through the vgmstream codebase.