Another thing to try instead of traditional baffles, not that they are bad, but I used to use a 'bubble tower' or at least that is what someone called it. Basically if your drain line is 1" PVC (or flex as it looks) go buy an 8" long piece of 2" PVC. Drill a couple holes at the bottom, and run your flex/drain into it. That way the bubbles stay in the larger tube, and water exits closer to the bottom with much less bubbles. I used it when my previous home built baffles were not great at removing air bubbles.
May not remove the noise but might help keep it in a smaller area. Just looked for a picture btu couldnt find one. Good luck!