How to respectfully and subtly tell dad and his new gf they're too loud when having sex?

Dad has recently gotten himself a much younger girlfriend whom he has moved in last month. My bedroom and their bedroom are wall to wall. The fact that they fuck doesn’t make me uncomfortable - so happy for them, but they do it on max volume. No joke. Every night at 11 and in the morning at 6 on the clock. These walls are paper thin apparently.