Why some people are more bothered by low-frequency sounds

Infrasound from ventilation systems can be rough. Too much static pressure can create a lot of weird effects. I've reduced the ECM fan speed in my furnace to mitigate most of the noise. The system was replaced in 2020 and the installers didn't bother to change any of the factory defaults. I can understand why this happens too. The dip switches are absolutely tiny. I don't know if I could manage to change their settings after hauling the entire furnace into the crawlspace.

I'd estimate a majority of the R410a ducted systems have this kind of deficit in my area. The furnaces all ship from the factory configured by default for the max speed and very few installers actually bother with tools like manometers and static pressure readings. Napkin math says they had my 3 ton system blowing air like it was a 5-6 ton system.