[Harp-L] A vibrato related question

["Bob Laughlin" <rlaughlin@xxxxxxxxxxxx>]

I found this guy, Ronnie Shellist, on Youtube.com, doing a search for "harmonica" clips.

Here's the clip in question:

http://www.youtube.com/watch?v=hs_OchfmBc8

First, this guy is, if I am not mistaken, tongue blocking? I use pucker exclusively, have for thirty-some years, save for octaves, and resist the idea of changing my whole approach at this late date, but there are things I simply cannot do with pucker alone.

Next, at 1:55 into the clip he uses a kind of vibrato (along with hand effects) that sounds like what I would call "phasing",,I've heard others do this, but never found out how to do it myself, to any degree. Is it done with the diaphragm? the throat? the tongue? It's something I definitely want to add to my harp tool-bag. 

Thanks in advance.

Bob Laughlin, Stater Brothers resident whistler and harp player, Huntington Beach, Ca