A strange sound from the sky with UFO sighting

An eyewitness from the USA taking night UFO on night vision, took one object unremarkable but during its flyby of the sky came a strange pulsating noise, strong roar was deafening.

Location: Louisville KY, US
Date: 2016-05-06

Long Description of Sighting Report

I was watching the nigh sky with a night vision device when i managed to capture a bright object/ ufo, and when the ufo got close to me it started to make a sound and it quits making the sound as soon as it got behind the tree line, i don’t think it was a computer problem or anything like that because you can still hear the background noise when ufo is making the sound. The most intriguing of this event is that i never heard that noise while i was recording the ufo, i just noticed the sound when i was taking a look at the videos i recorded that night, i was going to delete it because it didn’t seem interesting but that sound is just awesome.I have had incredible ufo sightings but this is the first one with sound. I still can’t believe it.