SubSonic frequency talk...

[Andrew Schrock]

This is from another list I'm on, kinda related to the discussion at hand.
All errors aren't mine, I didn't write this, so don't blame me. 

Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|

---------- Forwarded message ----------
Date: Mon, 11 Jan 1999 15:34:47 -0500
From: Jeremy Warner <jwarner at MIT.EDU>
To: Sasha Costanza-Chock <schock at fas.harvard.edu>, underground at MIT.EDU
Subject: Re: [604] SOUND:just in case you didn't read this coz it  didn't have a subject 

At 03:24 PM 1/11/99 -0500, you wrote:
>the US military has since then developed an array of weapons that utilize
>the same principle. they like it because it is directional - as you point
>out, jeremy.  I'm sure you're wrong about the potential intensity of this
>kind of directional sound, though - in 1993 russian researchers announced
>the development of a 'sonic cannon' that works this way and is capable of
>penetrating tank armor.

Well the intensity is theoretically only limited by the mechanical
abilities of the transducer.  What you have to remember, though, is that
the amount of power to produce an appreciably large ultrasonic wave is
extremely high, mostly due to the atmosphere's nasty habit of soaking up
high frequencies.  This effect also occurs at audible frequencies, and is a
function of temperature and humidity.  In any venue of over 600ft, the high
frequencies need to be boosted to compensate for atmospheric loss.  But the
problem becomes much worse at ultrasonic frequencies.  You can look up the
tables in the CRC handbook.

Jeremy
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