Personally, I wouldn't stress over the sounds in sex scenes and vocals and so on. The game, as it stands, simply completely lacks in sound effects and ambience. It gets a bit old listening to the same two generic (mind you, they're not bad tracks!) songs on repeat.
Adding at least two or three more tracks would be great, and more common sound effects would help make things feel more alive. A splash of water in relevant pool scenes, a rumble in the beginning of the dollhouse scene, this sort of stuff would really help flesh the game out, IMHO.