acoustics
"RichD"
A few days ago, I was in a room on the third floor, the
window was open, some people were conversating
down at street level. Their words came in, clear as a
bell, almost like being in the same room. I was surprised,
I thought the power would attenuate a lot faster.
Then I wondered if it also works the other way - could they
hear our conversations, just as crisp?
** Almost certainly not.
I recall a discussion of optics, and someone remarked:
'I see you, you see me' is pretty much a universal law.
Does that also hold for acoustics?
** It ain't true of optics or acoustics.
Egs. A peep hole device allows you to see who is outside your door while
being unobserved, similarly a periscope or telescope allows an observer to
be unseen.
A small hole in a wall of a room will allow you to hear what is happening
outside if you press your ear against it - however, very little of your
voice energy escapes the room through that hole.
....... Phil
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