Haier Energy Star ESA3183 Air Conditioner "fix noisy ducts" Questions

...fix is to replace both units and duct system from scratch which is not an option in my budget. Guy two was a retired HVAC looking for some extra cash for his daughters tuition with over 30 years ...

...noisy. I'd like to know why and if there's a way to fix it. Many heating/cooling ducts are metal, so they conduct noise quite readily from the air-handling unit to your rooms. To break the conduction ...