Is there any way to avoid the wierd audio bug when creating a 2nd character, you know the one, where it changes the actor voice of your 1st Character?

I haven't heard of any solution or potential avoidance, no.
The only thing I've heard is kind of annoying...
Go to the character select screen and select the character you intend on playing... Exit Brink and then turn it back on with that same character, do not switch. You should be alright from there.
I have my dialogue turned down way low because I can't stand the repetitive [censored] they say and this particular glitch that increases the volume of dialogue.