Blocking and the "Valsalva maneuver"

(In objection to blocking being caused by a stoppage of air-flow)

I once heard Bill's (Bill Parry) presentation. I was and still remain skeptical.
To me the "block" is in the "control system" that moves the
articulation along from one phoneme to another. It doesn't come
from "cutting off air". To use an analogy, suppose I am playing the
saxophone. One could stop me from going on with the music simply by plugging
up the air duct (Valsalva, if I understand correctly) or by paralizing my
fingers. But wouldn't sound still come out if I kept blowing with my
fingers paralized? That's where the analogy breaks down. In the case of speech,
"finger movement" would feed back (my educated guess) and determine how
much blowing is being done. So the whole system comes to a grinding halt,
but NOT because something just plugged up the air duct. I realize this
is mere speculation, and I am not sure if any therapeutic consequences
would come out of this, but it would be great to devise and experiment that
puts the issue to rest.

There is actually an observation that, IMO, puts the issue to rest. Some
blocks come with "sound" behind them! Unless I am dreaming, I have often heard
stuff like hmmmmmmmmm, hmmmmmmm, hmmmmmmPOLICY, for someone blocking
on the "P" of "policy". So air is actually flowing, just like it would be
for the "finger paralized" sax player.

I have pointed this out a few times on the list and never got an answer.
Will somebody please either agree with me or tell me why I am wrong?

One last point. I do NOT mean to carry the analogy to imply that some
form of vocal cord "paralysis" is the fundamental cause. Again it's the
sequence of articulatory commands from the brain that gets "stuck"
(my opinion and that of many).