This is a class given by the master, Arnold Jacobs, at the International Brass Congress in 1984. I had to adjust the volume up and down numerous times because of mic problems, audience questions, and Mr. Jacobs' movement on stage.
Thanks for posting! I lost my tape of this probably twenty years ago. I was lucky enough to have a few lessons with Mr. Jacobs and was a student of Dee Stewart (also a student of Jake), the person who first speaks first on this recording.
Around 1:13:00 he talks about how the worse he feels to more musical the brain is. And then talks about how having clear sound concepts in the brain translates to playing well. Wow everything he is saying is gold.