Nope. There is no evidence that people are actually hearing the hum described in the paper. In fact it's highly unlikely. Is there any evidence at all that the human ear can detect 0.1Hz?

I don't think it would come in thru your ear. Maybe resonating inside your body cavity?

I probably just don't know enough about acoustics, but could vibrations with a subsonic period travelling through the earth cause resonations in smaller air-filled cavities (e.g. underground air pockets/caves; the insides of buildings; bodies of water) that would then result in audible vibrations?

Yes, there have been instances of subsonic standing waves/resonance in hallways that have caused feelings of fear and reports of "ghost" sightings.

That's really just speculation, and it wouldn't likely sound like a "hum". Tinnitus and/or mains hum seems a much more likely explanation.