Strange sounds (stock)
On January 6 & 7th of 2019, YouTuber 'pennsylvaniaguy19' shared two videos of 'annoying' sounds he heard in the skies of Pennsylvania.

In the first video, he reports that he'd been hearing the 'slow droning, humming sounds' from around 9 am through 3 pm:

The next day, he posted another clip from his neighbor's property: