Keep in mind that almost -if not all- every enemy in Amnesia have a
notice.snt.
So if you don't specify which
notice.snt you wanna play, the game it's gonna use the first it finds.
If you don't rename the .snt to something else you can include the parent(s) directory of the sound to differentiate. Example:
ambient/1/notice.snt.
Or you can make a copy of the .snt and name it something else, it will still point to the correct sound(s).
example notice.snt > you make a copy in your cs and name it: asdf.snt
Then you go:
PlaySound( "asdf.snt" ...
It won't find another asdf.snt.