TIFU by not realizing my teens can hear me doing the deed

So this was an ongoing issue, until I found out about it. My family and I recently went on a family vacation with my parents and siblings and their families. We were all sitting around the campfire one night after a full day of drinking. My youngest (15) was in the house watching TV as she was tired and my oldest (16) was sitting by us adults at the fire. The adult guys were off playing frisbee (yes in the dark, light up frisbee). So the conversation was pretty basic until my little sister (27), was talking about sneaking in sexy time when her son was sleeping. My daughter casually says, "Oh yeah sister (15), can hear mom all the time when they are doing it!" My mouth dropped open and was just dumbstruck. My family is laughing their butts off, but I'm thoroughly embarrassed. I asked her how long this was going on. She said since we moved to our new place. We have been living there going on 4 years now!! I did ask my young daughter and she confirmed. She says that's why she turns on her music or wears headphones until she falls asleep most nights. Needless to say I have toned it way down and now barely make a sound....it's very hard to be quiet, but I do it for her! Ugh.

TL;DR: Teens can hear me doing the deed, toned it down after a lot of embarrassing conversation. Edit: added TLDR, formatting Edit: resubmission for TLDR