judyxyc,
You have to consider a lot of variables. One is the guy factor. There are undoubtably "bigger" more adept men out there than I. That being said, I led with that to my wife by saying, "Hey, there are going to be tighter women than you, right?"
That may sound like a rude remark, but an honest analogy. I figure my wife would enjoy variety in the lifestyle. For me the same is true, of course. With that simple assumption, you have to figure there is going to be different sounds coming from your partner. Maybe some you haven't heard before. Dirty talk, you haven't even comtemplated!
You have to be prepared to hear those things completely different. These "pleasure noises" should be a catalyst for you. Something that arouses you. This question is leading toward you other question about seperate rooms, and in doing so might lead you to think that a boundary will insulate you somehow. Does the idea of you or your partner enjoying themselves bother you?
Noises like that would be a clear signal to me that everything is going fine. ;)
Not only being in the same room and hearing the pleasure is sometimes key, being in visual contact with your partner is a way of consenting with the situation. A simple nod or wink, can signal many things. Even a verbal command or key word can be spoken if something isn't quite right.
That kind of leads to safety and control issues you need to also address. Trust factors are so important, and cannot be discussed "on the fly. Have a deep disscussion on that fact.
Have Fun! Be Safe!
OverKnght