audio telescope?
Peter Webb wrote:
You could in principle build sound lenses, but in practice mirrors or phased
arrays (as in sonar) would be more practical.
Using parabolic sound mirrors with a microphone at the focal point is
very common for many uses. I see them for sporting events, to focus in
on remote conversations, to capture the sounds of distant animals.
You could artificially
simulate any optical effect in this manner, but as far as I know there is no
practical use for looking down the wrong end of a telescope even when using
light, let alone sound.
Both microscopes and telescopes magnify. Looking at the wrong end of a
telescope makes the image smaller but also makes it dimmer.
So the effect would be to make sounds quieter. Since it is easy to
reduce sound in general with insulation and echo suppression there is
much less call for sound from a very specific direction to be reduced.
Consider listening to a rifle shot - Once I know the direction it came
from what's the point of reducing the volume from only that direction
when I can deaden sound volume it general?
It's not like the speakers at an excessively loud rock concert are close
enough together for a directional deadener to be a better option than
peak blocking ear plugs.
I know lots of places where light refraction and reflection is used in
nature, from eyes to fish scales, and lots of places where sound reflection
is used (every large animal's ear, bats etc), but none where sound
refraction is used.
Ears are wave guides. It starts to push the border between reflection
and refraction just a bit. It demonstrates that there can be a
continium between the two effects.
But that does suggest a possible application for sound refraction - One
effect is changing the direction of sound waves in addition to difusing
them. Chose only the direction change aspect and you might end up
curving sounds around corners. Sort of like how electricity works in a
wire.
How useful this would be giviwn how easy it is to build a sound wave
guide that is based on reflection I can't say. Sometimes it's fun to
build a project that uses an aspect of nature and the motivation does
not need to go deeper. Other times such a project leads to practical
applications.
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