Soulful,
Any change in the speaking of your art professor?
Wow! He sounds like one of the bravest people I know!
Imagine even coming to class when you know darn well students will make faces and roll their eyes!
One great show I saw years ago on TV was a demonstration that, reading together, speech impediments vanished. It was astonishing.
If your professor had, at least a portion of his lesson prepared in advance, and reviewed with an assistant, he might feel more at ease reading the beginning of the lesson together with the assistant...or with the whole class! (Or with the first student to snigger. I can see him crooking his finger at his worst offender, calling the student up to read the beginning of the lesson, aloud, in front of everyone. He-he-he.)
Several ideas tripped through my head while reading your question...
...How would he do if his listener wasn't actually looking at him...politely distracted and not 'hanging' on his next word?
...Would surprise help? What would happen if someone in his audience flashed a print of his subject, or something he is passionate about?
...Would hand gestures help? Could he throw in hand gestures instructing a student to do something while he was stuck on a word? ...Something funny; or as simple as putting away his umbrella? Gesturing for a student to come up and pat his back while he is stuck might break the ice.
...Could he speak more easily if he were to turn his back on the students...even just for a moment? Or to speak a sentence in sing-song? Or to play a snippet of comedy to distract people?
Just being a boy helped my husband grow out of his sudden onset stammering at age six...though it took four years. His began almost completely physically as the teacher tied his best hand, his left, behind his back. Of course, the meanness of the act did nothing for his innocent first days at school.
Dh is in his eighties, but always remembers that teacher's name.
Good luck to you and your brave professor.
Sheesh! Did you know that fear of speaking in public is the number one phobia in all the world?
(Come to think of it, it's the ones without this phobia you have to worry about!)
I mean, even posting a sentence or two on CureZone gets some people!
Fledgling
P.S. How about posture lessons and exercises? Maybe it is more physical than he knows. I highly recommend the Alexander Technique. The Dorn Method, here on CureZone, looks very promising.