I've been a little pissed about the voice volume problem, and I know a lot of other people are too. Here's an IM conversation between myself and a support staff person.
Christopher K.: Thank you. And how may I help you today?
Ethan: MW3 required an update the other day when I went to play. I downloaded it and went to play online. Used to, I could turn the voice volume all the way down and not have to hear anybody. I could have my tv volume up with gun noises and stuff but without any people noise. After the update however the voice volume doesn't work and whenever I play online, unless I manually mute everybody (which is very annoying) I hear people's voices.
Ethan: I chatted with another guy on here a little while ago and he told me to delete the update (he told me how) and then to re install it without my headset plugged in. I did so and there was no change at all.
Christopher K.: Okay... I know the most recent update was supposed to address issues with the microhpones... it's possible they had to change the functionality of the volume controls to do that
Ethan: Why would they disable the voice volume option but still leave it up there making you think you can change it?
Ethan: Will they put it back?
Ethan: people on the forums are a little hot about it
Christopher K.: I can't really comment on why any decision was made, or even if that's the case... but if many people are experiencing the problem, it's probably not something specific to your system. Let me see if we have anythnig on it.
Christopher K.: Okay, so it looks like this issue has been reported, and the development team is working on it. It is not something that will be fixable here and now, though. Unfortunately, I don't have an estimated time frame to give you on when it will be fixed.
Ethan: Okay, so they're working on it and will try and fix it soon?
Christopher K.: I can't promise a time frame. But yes, it is being worked on.
Ethan: or, will fix it soon. It's not very complicated.
Ethan: will there be another update? or will I have to keep checking the voice volume slider to see if it's working?
Christopher K.: It's a little too early to ask that question
Ethan: well thanks
Christopher K.: you're welcome
You have disconnected.
Hopefully this helps anyone like me.