Sound-ONLY of large aircraft passing close overheadClear blue sky with slightest white haze just after sunset, quiet environment. I was outside, began hearing a "mechanical-engine" sound that got louder and louder. Couldn't identify at first, I presumed a semi-truck or train a few blocks away (but NO 'exhaust note').But it got louder and closer, I realized it was "passing overhead". I stood in the middle of the street, hat off, looking up, turning around and around expecting to see this LARGE aircraft that my ears suggested should be just a few thousand feet up. (I am a Commercial Pilot, have heard many large aircraft, but could NOT compare this "engine-mechanical" sound to this "imagined" 747/B-52 size massive aircraft I could NOT see.) Its path overhead seemed to be NNW (toward Fairchild AFB from here) and I imagined it was decelerating but could be Doppler playing slight sound-tricks.Entire event lasted roughly 60 seconds as the sound faded to nothing to my NorthNorthWest, with never the slightest visual hint.Path crossed over my location Lat 46.91 & Long 117.07 heading to the NNW.Sound peaked in the 80-90db range.((NUFORC Note: Please see similar report from Garfield, WA, for the same time and date. PD))