I've discovered that I can hear it REALLY loudly with my right ear (with a finger jammed in my left ear), and hardly at all with my left ear (w/ my right ear plugged)- clearly due to a difference in my hearing abilities and would explain the wavering 'off' stereoscopic image. Most interesting: if I hum the note, the HUM seems to stop for a moment or two, then immediately fills in the auditory vacuum. It's almost like my humming creates a temporary baffle that mutes or 'defeats' the waves- like noise cancelling headphones.

Last night was quiet enough outside that I could hear it outdoors... I also now remember how loud it was last summer. I'd like to go to other people's homes in the area and see if it can be heard. I'm also considering a late night source search when it gets really bad--- does anyone have any suggestion as to what type of device I might need to detect or measure this sound. If I can get at least 3 accurate measurements I can begin to triangulate the source direction and track it down (this assuming there's a primary direction). I"m under the impression this is an overlapping phenomenon, so I'm sure there are multiple sources--- whether low frequency towers, ELFS or whatever other networking might be causing this.

And I can hear it right now, at 10:00 am, in my otherwise silent home.