Underground bases

[Underground work?]

[vid 2012 May] Strange "Windsor Hum" has local officials demanding answers The 'Windsor Hum' is the name given to the recurring and invasive low-frequency humming noise plaguing Windsor, Canada for more than a year now. The noise peaked last year and then subsided for a time, but a few months ago the hum returned with a vengeance and has Windsor residents and Canadian officials demanding answers.  Canadian scientists are claiming that the sound is coming from across the river, from Detroit, but Americans say they can't here it. American agencies, like the EPA, aren't interested. Canadian diplomats formally raised the issue with the U.S. Department of State last September, and with the return of the noise in February, they intend to raise the issue again.

 [2011 June] Tiny village is latest victim of the 'The hum'

Strange “Hum” around Newtown, Brookfield since 2009