[Harp-L] What kind of effect is this?

[martin oldsberg <martinoldsberg@xxxxxxxxx>]

Almost at the end of this video the harmonica comes in, with a great trombone-like sound (somewhat emphazised by the visual prescense of a trombone).
  I wonder, is this just heavy distortion or is something else at play?
http://www.youtube.com/watch?v=W5d3Md1BARA
 
From Charlie Winstons first cd. Several songs there with discreet and elegant harmonica backing from Ben ? (can´t remeber last name right now). Use it as a lesson, you who overplay ...
 
Cheers,
Martin