A case of positive feedback?

From Stefan Balke (960312.1200 MEZ)

Rick Marken (960307.0900}

Here's the positive feedback loop:

    v-->i-->|amp|-->o
        ª |
        > >
        > >
         -----------

The mic input, i, to the amplifier (amp) is your voice, v, plus any output,
o, from the speaker. The amplified speaker output, o, feeds back additively
to the input to the amp, i. Thus, the fed back output, o, continuously causes
_itself_ to increase; this is positive feedback. The runaway increase in such
a loop continues until the limits of the amp are reached and/ or the
influences on the input are removed (you stop talking into the mic and/or
protect the mic from the output of the speaker).

What do you think, could it be considered as a case of a positive feedback
function if an allergic person, suffering from neurodermitis or hayfever,
gets a scratching attack?

This is the assumed positive feedback loop for scratching:

     hm-->i-->|s|-->o
          ª |

···

        >

          > >
           ---------

The perceptual input, i, to the itching skin (s) is the scratching hand
movement, hm, plus any output, o, from the skin.
The amplified itch output, o, feeds back additively
to the input to the skin, i. Thus, the fed back output, o, continuously causes
_itself_ to increase; this is positive feedback.

Does it sound reasonable?

Stefan