Soft Chamber HBOT (No Oxygen) for Hyperacusis with Ear Pain

For budget reasons I cannot afford the hard shell HBOT with oxygen, but I’ve located some places that can offer lower cost HBOT (with only like 25% oxygen as opposed to 100% oxygen) so it’s just the pressure that could relieve symptoms in this case (assuming between 2-2.5 pressure).

Would this treatment even be of benefit if the oxygen part of it isn’t included in the process? I have a TON of pressure in my ears and painful hyperacusis directly in tandem with noise exposure.