Some ideas:

for i in DLG*-*-*-sprite.ogg; do echo "${i//[^0-9]}" | head -c 2; echo ;done

If you are sure they are all same length:

for i in DLG*-*-*-sprite.ogg; do echo "${i:3:3}" ;done

A couple of ideas:

for i in DLG*-\*-\*-sprite.ogg; do echo "${i//[^0-9]}" | head -c 2; echo ;done

If you are sure they are all same length:

for i in DLG*-\*-\*-sprite.ogg; do echo "${i:3:3}" ;done