it's in LOG scale, not linear scale a 3db difference doubles the power required the drive it at the same frequency. the difference in bass db is around 2-3. They are not measuring with human ear but with microphones. Test it with a dap with a software preamp, increase it by 2db, you can clearly hear the volume change.
We begin this discussion with your absolute belief that the Golden Ears graphs had to be wrong I notice you are no longer making that assertion.