Thank you for sharing your filmmaking thoughts and experience, Penny. I never realize the four act structure in porn before until you mentioned it. I always view porn as one long sexually entertaining act.
As for your question, I think sound is pretty tricky to deal with to heat up a porn scene since it’s mostly the women that viewers want to hear instead of various objects. But in your case maybe you should capture the sound of each of those object and/or images that turns you on. Begin your video with the slightest sound mix of your voice and the object and steady increase the volume with the various object in frame with you and the object before you decrease the volume as it’s ending. Best of luck with everything and keep up the good work.