For those looking at the waterfall images: Y-axis is time, X-axis is the frequency axis, colors are intensity. Jus a spectrogram that's been rotated 90 degrees to the left.

When you play the sound, the start is at the bottom of the image, and then moves upwards (kind of like Guitar Hero). Some of them can be quite musical, like the THOR (https://www.sigidwiki.com/wiki/THOR)