It's seems like either a pressure in the cab is unbearable or a frequency caused by vibration you just can't hear but it fatigues you makes your ears hurt or ring vertigo. Things I have noticed are wind sounds in the windsheild area like the window is open or the blower is on but it isn't. I also notice a bass booming sound when hitting bumps or rough road at lower to middle speeds, every bump a bass boom. There is a slight vibration in the gas pedal and strearing wheel as well maybe related maybe not. I noticed the booming sound a little once when I opened the back passenger side window at idle that makes me feel like it might be the metal used in the cab or the shape of it acting like a drum.