Our houses are too far apart to hear them. I have accidentally interrupted our neighbors, and best friends on one side of us. Just came to the door in the middle of the day (they have a baby, so that's when the kid is asleep) and she came to the door, all mussed and distracted, and I knew immediately what was happening. I just, "OMG, I'm so sorry for interrupting. Call me later." And she tried to give me the, "No, you weren't interrupting anything...." I just looked at her and said, "Get back to you Man, you both need it." and ran across the little field, back to our house.
My Man always says, "The neighbors must have heard you that time." But, I doubt it. The guy on the other side of us is, like 37 years old and lives with his mother and he's just creepy, he just got a new girlfriend (very young, which is all he seems to get) and I would NEVER EVER want to hear them having sex. I doubt his mother has sex at all, poor thing. There house is just too far to hear anything. Thank God!
The guy behind us on one side (it's a weird set up, as we have an acre, that goes from one road to the road behind us) and have two neighbors on each side) is a biker and we've heard loud parties and Harley Motors, but no sex. The people behind us on the other side, we never hear ANYTHING from.