Strange sounds stock
On November 25, 2019, YouTuber 'Shannon Maybe' shared footage of strange trumpet sounds she heard in the skies of Anchorage, Alaska around 1:00 a.m.

A commenter on the video attributed the sound to road graters which she dismissed:
... it's not tho.. I looked up other videos on here and the sounds are the same in other states, some during the days and with no snow out...
Another commenter said the noise was from the HAARP project, to which she replied:
I've lived here my whole life, I've never heard that here before ever! HAARP is here in Alaska.