🚀 go-pugleaf

    In previous postings, the idea of a headphone/microphone combination
to cancel out unwanted noise has been discussed. I started thinking, 
"why all the electrical stuff?"

   You have this (mechanical) wave, right, travelling along towards the ear..
by the time it gets there, it will have a flat wavefront (in the majority
of cases)... a very small part of this flat wavefront will hit the ear and 
pummels the ear drum, while the rest of the mechanical energy bouces about
uselessly.. you could use that waste energy to cancel the sound at the ear.

a 'diagram'...           |||||||    
                       |||||||||||   
                     | ||||||||||| |
                     |_||       ||_|   Large circular disk
                     |(   O  O    )|  __ diaphragm
                     |_@         @_|     mounted on headphone structure.
                    /|  |  ___  |  |     
                   / |  \       /  |
           ear cup       \_____/

    Sound incident on the above diaphragm, will cause it to oscilate
in a standing wave, with the centre moving in  anti-phase to the sound...
getting the proportions of surface area inside, and outside of the ring 
of the ear-cup correct will result in the diaphragm adjacent to the ear
being entirely stationery  i.e. NO SOUND

    Anyone got any further ideas along these lines??
The resulting headphones would be quite bulky.. could they be reduced
by having more surface area in less volume? And what about directionality??

  All these questions, and less, next week  same bat time, same bat channel.

Disclaimer: I don't know what a disclaimer is, but this one is going to be
squiggly ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.