[ARC5] zero

[Richard Knoppow]

----- Original Message ----- 
From: "J. Forster" <jfor at quikus.com>
To: <provero at ct.metrocast.net>
Cc: "Richard Knoppow" <1oldlens1 at ix.netcom.com>; "Bruce 
Long" <coolbrucelong at yahoo.com>; <kgordon2006 at frontier.com>; 
<arc5 at mailman.qth.net>
Sent: Friday, August 17, 2012 4:40 PM
Subject: Re: [ARC5] zero


> I've seen pics of a Japaneese sound detection machine like 
> an array of
> tubas on a truck body.
>
> Best,
>
> -John
>
    A correction.  I said the hot-wire microphone was the 
same as a thermophone. My error, its not.  The thermophone 
is a _source_ of sound using a wire or ribbon which is 
heated.  Thermophones are used for producing a known sound 
pressure for calibrating measurement microphones.  There is 
a brief summary of an article describing it at:
http://prola.aps.org/abstract/PR/v19/i4/p333_1
    There may also be a paper in the _Bell System Technical 
Journal_ which is available free on line, do a google search 
for it.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com