I came upon this after following a series of links while reading about solar wind. It is a recording of VLF electromagnetic signals emanating from an aurora over Alberta, Canada. It is one of the coolest, most mystifying sounds I've ever heard:
https://www-pw.physics.uiowa.edu/mcgreevy/30a1652.wav
Several more, and much more data, can be found here:
https://www-pw.physics.uiowa.edu/mcgreevy/