Dennis Foley is not well regarded by acousticians. He does NOT practice what I would call proven and trusted methods.... Try Nyall Mellor or Anthony Grimani.

If you have a room of known dimensions post them here with windows and doors as well. Sketch is great. I routinely plan rooms with software renders for installs. It is not a “black art”. It is not magic at all.

The pile of University Textbooks here indicate it is entirely empiracal and methodical if you follow proven principles. Please DO NOT confuse what 2x6 or Reblux or anyone else says about your room as facts. Measurements are facts.

A real person in real life will need to measure your room in person if you are going to treat it. You can do it. I can walk you through it. 2x6’s pal likely reduced his RT60 below 0.2s. Bad news.

Anyone who has heard a properly treated room would not deny its overwhelming importance.