In 2024, researchers transformed readings of an epic upheaval of Earth’s magnetic field flipping 41,000 years ago into an eerie, auditory experience.

Now a team containing some of those same scientists has sonified an even earlier flip, from epochs ago.

The resulting cacophony is an unnerving translation of geological data on the Matuyama-Brunhes reversal, a switching of the planet’s magnetic poles that took place roughly 780,000 years ago.