suggestions wanted a.s.a.p

Richard Norman rsnorman at
Mon Mar 19 19:52:14 EST 2001

Is there some reason you want to block ultrasounds that you can't hear
anyway?  Is there some reason to believe that microwave ovens
produce ultrasound frequencies?

I am just curious.  In any event --  sound, like light, travels in straight
lines when
considering distances much larger than the wavelength.  Sound bends around
objects (diffracts) if they are smaller than the wavelength.

So bass sounds (frequencies to several hundred Hz and wavelengths of greater
than 1 meter) tend to wrap around barriers, but very high frequency sounds
(frequencies of 10kHz or so and wavelength of a few cm) are easily shielded.
Ultrasonics above 33kHz have wavelengths of less than 1 cm and so a simple
styrofoam box will produce adequate shielding.

"Juliet" <juliet at> wrote in message
news:995rvq$ltp$1 at
> any suggestions how one can block ultrasound frequencies ?Is there an item
> on the market that can absorb or block high frequency sounds being emitted
> by microwave or other devices?

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