We really do not know what is going on with the many claims for auroral noise. There is no known mechanism that can produce this, and despite many sensitive measurments and searches, it has yet to turn up in any instrument. It is not heard every single time, and the incidence of detection is so low that some feel certain that its source is inside the human brain either through a psychological effect or some other unknown process.
All answers are provided by Dr. Sten Odenwald (Raytheon STX)
NASA IMAGE/POETRY Education and Public Outreach program.