With the Glasgow Haskell Compiler installed, you can build this
program with something like:

  ghc --make space.hs -o hpeano

This program expects audio in a headerless unsigned mono 8bit stereo
form.  Sox users for example would type something like this to make
suitable input:

 sox audio.wav -t raw -r 10000 -u -b -c 1 audio.raw 

Adjust the samplerate (10000 in this example) to taste.  To experiment
with feeding it interlaced stereo samples, put -c 2 instead.

It'll choose a recursion level to suit the amount of data you give it.
If you want a smaller image, you might have to reduce the sample rate
rate a lot before qualifying for a smaller recursion level.

Give it the name of your input file as a commandline argument, ie

  ./hpeano audio.raw

You'll get the output in a file called out.ppm .

All feedback, ideas, image outputs and patches very welcome to alex
(at) slab (dot) org .

Thanks!

alex