The neighbours abouve our flat are a couple around age 30. When she has her orgasm I can hear well her deep and slow moans for a minute or so. Always quite the same, but she enjoys it a lot.
However, every two weeks or so her partner is not at home for 2 nights. Then she has visits from other men, all of them either driving a Mercedes or Audi. But that's not the point.

Each time she has a different guy the final moans are different: not slow and deep but faster and squeaky. I guess she is not aware of that differtiation ...