Fairhaven was being run 24/7 with an open door policy to help the crew deal with stress.
Stem to stern (tip of the hull to the rear end of the nacels) Voyager is 345 meters long and 135 meters wide.
If someone is having sex 345 meters away you can usually hear it.
If these sketches are accurate
Given the size of the door into the holodeck, then the dimensions of the holodeck itself is perhaps 12 by 8 metres.
With how the Riker explained that the holodeck works in Encouter at Farpoint in conflict with your senses, that you're looking at a holographic sheer that seems to be miles and miles of countryside, which is actualy a thin cutain persisting an optical illusion between you and someone else centermtres away getting jiggy in front of the flip side of the sheer. Sure they can use sound baffling technology to mask sex noises and perhaps other peoples routine sexless adventures with perspective and trickery to have the crew believe that they are in vast alien vista instead of an oversized stateroom... But what about the smell?
How do they baffle the sex smells?
I saw a movie yesterday called "Ruby Sparks". A celebrated author is so lonely that a character from his novel leaps out of the world of fiction and becomes his girlfriend. She doesn't know that she's not real, but every time he adds to the book she's in, it changes her character, it effects who she is and how she operates. A very tedious movie until she gets bored and tries to leave him. Then he keeps making changes until she's unbearable and Ruby is not the "person" who he fell in love with until in the hieght of an argument she says "you can't control me!" and it it gets really fracking sadistic as he prooves that she has to do every thing his typewriter dictates.