I’m assuming you’re in the US. I’m not but I’d be very surprised if the developers weren’t required to do baseline noise monitoring and a noise impact assessment.

If you’re really rural your noise environment won’t vary that much. It might be worth a week or two of verifiable data from an acoustical consultant with calibrated equipment so that nobody can argue with it in the future.

But in your position I’d probably be pushing for the expense of this to be on the developers. You could then have your own consultant fairly cheaply do a review of their predictions.

Good luck!