That has to be one of the creepiest things I've heard... aside from messing around tuning into number stations while extremely tired...
It sounds almost like a motor speedway in the distance... but it can't be, otherwise you'd hear the pitches all raise up together all at the same
time... you wouldn't hear a whole lot of idling and only one pitch raise.
Maybe a bunch of Harley enthusiasts have gotten together just over the hill, lol.
Really though, I have no idea what would make that noise.



