Last year, as many might vividly recall, I personally captured an ominous and mysterious sound that frightened many locals, and caused me to have many sleepless nights as a result. Thankfully, a keenly aware teacher at a local elementary school was able to quickly debunk the sound I had captured with my iPhone, pointing out that it was the ventilation ducts on top of the classrooms that reacted to the cold air when heat was released on a timer.

Now, a new sound has been recorded that might raise the hairs on the back of your neck, and if anything, even more questions. This time around, the sound was recorded by a Youtube user going by the name of mr13karrot and shows footage of a darkened Missoula skyline with an eerie, and very audible noise recorded in the middle of the night.

Having lived near the Missoula airport for the last five years, my first guess is that it is the sound of a large plane warming up its engines. Or could it be...something else?

Listen, and decide for yourself. Better still, give us your thoughts and possible explanation in the comments below.