>A non-electronic solution would be to use a microphone which has its
>diaphram open to both sides. In theory ambient noise cancles out (equal
^^^^^^^^^
>pressure on the front and back of the diapram), but directional sound
>(e.g. voice) does not.
In whose theory? There is no such thing as nondirectional sound.
Any noise is propagated in some direction as a wave, and its impact on a
plane is proportional to the cosine of the angle between that direction
and the plane. Thus the effect of such a microphone would be to cancel
sounds coming from your left and right, but not those coming from your
front and rear. If the speaker you wanted to listen to happened to
be to your side, this microphone would reject it. And if the ambient
noise you wanted to reject came from ahead or behind, the microphone
would pick it up loud and clear.
Vaughan
--
Subcription/unsubscription/info requests: send e-mail with subject of
"subscribe", "unsubscribe", or "info" to 
Wear-Hard Mailing List Archive (searchable): http://wearables.blu.org
From Wear-Hard Mailing list Archive (WH)
Maintained by R. Paul McCarty
Archive created with babymail