From Just Solve the File Format Problem
BNSF (IS14, G.722.1) is an audio format used in some computer/video games. There are variants with different subcodecs.
The first four bytes are
42 4E 53 46 (spellling BNSF in ASCII), and bytes 08-0B are
49 53 31 34 (spelling IS14). The bytes in between can vary.