Being me, I would drive around to the farm whan I am hearing the noise & see if it is louder there or you see anything that could be making the noise.
I am blessed to know our head sheriff. I saw an unusual fluorescent light on in an old delapidated building on a neighboring farm & knew the owner had dementia. Called the sheriff to check it out. He actually called me back after investigating it & let me know that there was nothing going on inside the building. Lol....I pictured grow lights for pot.