I get a message like yours every once in a while.   I have been victimized by a cut-and-paste of the original interview.  I also did not realize that these things now stay on the internet basically forever.  In the olden days, you could get away with mistakes of that sort because it was showing up once on the local TV station and it would  soon be forgotten.  But times have changed.

So, no, the strange sounds do not come from the aurora.  In that awful interview, I got side-tracked in discussing the fact that the aurora produces electromagnetic waves in the audio frequency range (a few 1000 Hz).  IF  you use an antenna to capture these frequencies you can replay the waves. All I had heard at that time was something that resembled the sounds that you can play when you record these electromagnetic waves.  I thought maybe people were recording that.

Obviously that is not the case.   The sounds appear to be real and have a very metallic nature to them.  Maybe it’s a train or someone sharpening blades on a scraper or just a snow plow.  The next question to address is the distance.  Obviously people do not see any obvious source.  But sound can be guided over very large distances under the right conditions.  A temperature inversion is a good way to do this.  The speed of sound is smaller at colder temperatures so that in an inversion the waves from a source end up heading back toward the ground after a while.  The distances can be quite large.  Also, the sound waves might become guided and stay near the ground if the inversion is strong and over an extended region.   Think of it as optics done with acoustics with the air playing the role of the refractive medium.  

Since you are a physicist I may not have to add more.  There are good references on the propagation of sound.  As for the fascinating electromagnetic waves, ask google for “auroral sound” (even though it’s not really sound) and watch for the university of Iowa site.  You should be able to play the files and get a bit more info on how the electromagnetic waves are produced.

I could give you more, but things are currently awfully busy around here.  If you need more, just let me know. I’ll have more time next week, I think.