If I remember correctly , you can no longer hear some ones engine running if your engine is running. I.E. turning down you engine volume does not help hear the other person correct?
HiTech
o.0 Didn't know that, sorry returning player here. Great job as usual.

I assume that also carries forward to track sounds as well?

Oops, forgot about that. hehe
Maybe he had a bad moment in an airplane and used a bad analogy? 
Nope actually I had a moment in GVs where I was sitting behind a mound, and could see a tank roll by me from the commander's view. Went to gunners view to find that I was a little short of ground clearance. So started up, just to move a little bit further up the mound. As soon as I did that the enemy GV stopped, turned towards me and got me. After a few more similar occurrences I thought they were hearing me start up while rolling themselves. Guess its just their better SA.
What I was suggesting is that both internal and external volume levels be linked, so that if I lower my engine or track sounds, the enemy GVs are also automatically reduced.
But nvm, I guess HTC's already covered it.