The quiet sounds is the problem of Android 4 only. It is impossible to solve it. I did nothing with WI-FI.
I have found an app, named AnEQ on play store. It is able to boost up volume. Not sky high, but is is better now.
I am not allowed to put links play.google.com/store/apps/details?id=de.ebbert.audioeq.free&feature=search_result#?t=W251bGwsMSwxLDEsImRlLmViYmVydC5hdWRpb2VxLmZyZWUiXQ
There is a paid version also.
I have also found some config sound related config files, but they might be GingerBread specific or something, as they are not found in your ROM. I mean this article:
I am not allowed to put links androidadvices.com/increase-volume-android-mobile-phones/
The links in the article are dead now, but they are at least traces on what to look for.
--Trifo