Why would increased ear pressure increase sounds by 10 to 15dB? That is a significant increase given how decibels actually work, something akin to 10 times louder.
If increased pressure is proven to make sounds 10-15dB louder than we have likely uncovered the cause of hyperacusis for many people.
Do you have a link? I would like to read more on this; especially since most people I know with ear pressure actually had muted hearing.
It all has to do with how are your eustachian tubes are (open or closed) and the ear pressure its creating (you can combine it also with how each nostril works). In my worst ear (most ear pressure) I can't hear well because my et stays closed all the time (it's like I have an earplug constantly in my ear and my tympanum doesn't respond to sound as it should to protect its self from the enormous amount of pressure). In the ear with the most ear pressure I hear sounds as a bit quieter ~10db. If I yawn I can hear normal (which is when the pressure equalizes because my et opens). In the other ear I have increased ear pressure its less than the ear pressure of the right. The et is also closed but the ear pressure is not enough to make the tympanum to tense up completely. In the ear with the increased pressure I hear sounds louder ~10db because I have increased ear pressure and the tympanum still responds to sounds.
I concluded the above from my own experience with my ear issues and from what the 4th ent said about ear pressure. The last ent said that increased ear pressure causes sounds to sound louder to the person. I have thought the rest based on my experience with my most pressurized ear.
Unfortunately, I don't have any link to prove this increase in sounds but I will give you a link which explains eustachian tube issues and what someone hears when they are open/closed: https://www.raleighcapitolent.com/blog/eustachian-tube-problems?entryid=13&tabid=89