Switching Between Tongue Blocking And Puckering

[marc@xxxxxxxxxxxxx (Marc A Dashevsky)]

Ken wrote:
> If you don't think there's a difference between tongue-blocking tone and
> puckering tone, listen to Walter Horton.  You'll hear when he switches.

The only WH material I have is on the Jimmy Rogers Chess album.
Does he do any switching on _You're The One_ or _Walking By Myself_?
If so, please tell me where.  I'd really like to train my ear to
distinguish between the two sounds.

I own a lot more Sonny Boy (both I & II), Little Walter, Taj Mahal,
and Carey Bell material, so if anyone knows other songs on which they
switch between tongue-block and puckering, let me know.

Thanks,
__Marc