Here's what BB King has to say ...
http://www.youtube.com/watch?v=Bt73TC9xRz8
(The movie is IMMENSELY amusing, too. Sorry if anyone's offended.)
=========
I guess we're talking about a serious question, however, I'm not quite sure which way to approach it:
everyone's music is heavily processed, if you listen to it on a CD.
IMO, smooth jazz is characterized by the use of a lot of loops and overdubs -- although both could be duplicated in a live setting. I've also seen a number of "smooth jazz" musicians use drum machines and such. This tends to give a more precise beat. Heck, some go so far as to sequence most instruments on a computer.
The person I reference is
Bob Hinz. I took an Electronic Music class from him in college and even taught one of the classes, once -- because I had more electronic stuff than him, at the time -- so, I might have more than just a grain of knowledge. This time.
Now, if you want to talk the
sound or
form, that's a bit like asking how to define jazz: if you have to ask what jazz is, you'll never know (Louis Armstrong). IMO, smooth jazz ... is really smooth. Smooth jazz doesn't swing, it's also not necessarily complex or challenging for the listener: you won't have something in 7/4 time or something like that. It's just ... smooth.