In Italy, instead of saying "I don't know", you can say "boh?" with the oooo sometimes drawn out. It's something you start to understand from the context, but is by no means some kind of universal sound.
In Japan, the equivalent is "sah" with the aaaa sometimes drawn out.
Hey, yesterday you know, I want to the mall you know, and there was this sale, you know, it was totally cheap, you know, so I bought 3 pairs of shoes, you know, aren't they great!?
In Japanese you can replace every "you know" with "sah".
You can put "sah" at the end of sentence when you don't know something or are contemplating but I wouldn't translate it in that case as "I don't know". Rather more like "Hmmmm...." as in "I wonder" like the feeling this emoji is trying to express https://www.google.com/search?q=hmmm+emoji
Q. What is that thing?
A. Saa (dunno)
My guess is that the Italian "boh" is the same.