What would be a good way to thumbnail audio?

I want to represent an audio file in an image with a maximum size of 180×180 pixels.

I have been thinking about something similar to what Soundcloud does, although it will require some chopping and stretching to mash it into the square:

I wonder if any of you have something for this. I have been searching around for a bit, mainly audio visualization and audio thumbnailing, but I have not found anything useful.