Some how it seems a number of folks in aviation have this problem. Not sure if it's the noise or the altitude change.
Mine was an unusual combination. The prop of a P-3 is fixed to turn at 1320 RPM. Four blades = 4X1320 = 5280 Hz sound X4 engines. I also taught flying for decades. 2 blade prop at 2500 RPM = 2X2500 = 5000 Hz. Really beat-up on my 5KHz sensors.