Hi,
If anyone needs to plot spectrograms, I just updated the timbreID examples with improved plotting patches. The old patches used structs, which were really really slow to draw. The new ones rely on GEM and are much more useable. You can plot cepstrograms as well.
I also recently added a classic vocoder patch based on a Bark-spaced filterbank. You'll need the latest version of timbreID for all of this to work. If you're interested, the library & example patches can be downloaded in separate packages here:
http://williambrent.conflations.com/pages/research.html#timbreID