This has been going on for several years now all over the globe. Linda Moultan Howe has been reporting on it for some time on her website earthfiles.com. I've seen footage on YouTube of the same sounds both in Europe and North America. She also discusses it with George Noory on Coast to Coast AM.
I say it's human made, amplified and fed into a huge speaker. There are a few times you can sense it's getting feedback that makes it sound human made to me.