Auroral chorus can be detected primarily around the magnetic equator, specifically in two distinct frequency bands, one above the equatorial half gyro-frequency and one below it.
Distinguishable on high resolution wideband spectrographs, the wave amplitude grows linearly then switches to non-linear.
Historically, the sounds have been associated with spiritual events by Inuit in Canada who regularly experienced auroral chorus on cold, windless nights.
The specific nature and source of the auroral chorus is a continuing question in space and atmospheric research.
Cluster satellite observations suggest that the sounds are seemingly generated by numerous sources in rapid motion.