2012 Strange Humming Sound Heard Nelson, BC, Canada : Feb. 4, 2012

My living room window was open just about 15 minutes ago when I almost fell asleep here in Nelson, BC, Canada. I heard a dog freak out , outside and run away, then the owners whistling for it to come back and they just could not find him and then suddenly , their voices disappeared, then, of course I start hearing this humming noise in the sky which I had never heard before I poked my head out