Honestly I don't know mainly because it's unclear if that dat file is one unique BNKl or it includes more standalone files, for sure there is no index that references these files.
I bet this is just a container and the index is somewhere else, the good news is that it's easy to dump all the BNKl files:
findloc OFFSET binary "BNKl"
get DUMMY long
findloc NEXT_OFFSET binary "BNKl" 0 ""
if NEXT_OFFSET == ""
get SIZE asize
math SIZE = NEXT_OFFSET
math SIZE -= OFFSET
log "" OFFSET SIZE
math OFFSET = NEXT_OFFSET
while NEXT_OFFSET != ""
While for playing them I don't know if exists a converter or player.
I can move the topic in the Audio section if that's ok for you.