Point taken about 'свой', I was 'clutching at straws' there; trying to salvage something from a rather poorly constructed sentence!
I think шум is kind of background noise, then. And звук is just a bit more general.
What verb is 'дотрясся' from? I can't find it in dictionaries.
полез в карман:- If a dictionary says 'Разговорное' or 'Разг', I guess that means it is an informal, spoken use of the word, rather than idiomatic as such?