12 month old not scared of loud noises

[Gabbbbbbby]

This is a strange question, but how normal is it that my year old baby is not scared of loud sudden noises, for example a balloon going off in his face (it's just been his birthday, hence lots of balloons around)? He's very chilled out in general so I guess it's just his personality? It makes me jump though, and he acts as if nothing's happened!
I've no worries about his hearing, he responds to his name and things like that.

I don't think it's that unusual - does he look at you when the loud sound happens? as if to check your reaction (that would be an example of social referencing).

@AladdinMum thanks for the reply! Yes, he looks round at me with a slightly quizzical expression. But no jump or startle at all, and one went off in his face this morning!