can you screenshot your audio import settings?
are you using "audio mixer" or just individual audio "source" volume levels to mix?
My audio import settings essentially follow this guide.
So for example, all my songs have those settings, and all small repetitive sounds look like this. Note that I played around a lot with those settings and it didn't seem to make much of a difference...
I'm only using audio sources for my volumes, that might be a problem?
Thanks!