Aaron Wolf's excellent Tonal Plexus demos

Cruising around Aaron Wolf's pages to find his barbershop
scores (which he seems to have taken down), I found this
excellent post containing three videos of him playing his
Tonal Plexus keyboard

http://wolftune.blogspot.com/2011/03/tonal-plexus-microtonal-keyboard-3.html

(I also found a note that says he's written a "treatise"
on barbershop intonation and as of 2010 is looking for a
publisher. Aaron is a top-notch musician and researcher
and I hope to read his report soon!)

-Carl