It reminded me of UFO sounds.
Whatever it was, he must have listening really attentively, since the volume on his hearing aids was up loud enough to cause him pain when Albert knocked.
Yeah, exactly what I was thinking, sounded just like "Engel" by Rammstein!
Which would make sense in a Lost Highway kinda manner.
I was wondering if he was making a bird call.
Bingo! I actually posted this on a new thread, having missed this one. It is a bird call, indeed, but I'm not familiar enough with the birds of the West to make a positive ID. As an East Coast birder, it sounds similar to the song of the Wood Thrush, a melodic forest dweller, but it's not an exact match. My guess- it's a reference to a place "where the birds sing a happy song, and there's music in the air," Twin Peaks or perhaps, the Black Lodge. But it's David Lynch, so your guess is as good as mine.
I think it's definitely Engel. Had it stuck in my head all day then it hit me.
Rammstein to me
It's Nino Rota's theme for the Fellini movie "Amarcord". Lynch is a big Fellini fan. To me it's just a joke for movie buffs.
If you guys can make any symbolic meaning out of this, though...