From what I gather, there are at least 3 known sources:
-cooling system or other component that runs when vehicle is parked (unique to Model Y?)
-resonance from body/chassis (when driving, known issue with several other vehicles)
-hatch buffeting (when driving, known issue with Model S)
I am considering a measurement mic that can pick up infrasound. Measurement Microphones — Earthworks Audio
If the problematic sound is infrasonic, headphones or earplugs wouldn't really be of much use.
I agree - my best guess is it's an interaction of heatpump/cooling system mounting, car resonance, and I perhaps hatch buffeting, but we drove the Y for a bit yesterday with the hatch up, and the noise seemed just as loud. Individually none of them are that bad, but get two or more happening at once...
I'm also trying to figure out how to digitize the noise. The best mics I have need a 48V phantom supply, so I'm thinking about setting up a laptop, my Pro Tools 003 box (from a 12V inverter) and a mic in the car. I'll certainly let everyone know if I pull it off. Service appt is Wed so I have a hard deadline...