[Milsurplus] Throat Mike

[Mike Hanz]

W7QHO@aol.com wrote:
> I recently picked up a WW2 T-30 throat microphone at a fleamarket.   Hooked 
> it up to my ART-13 and made a few tests with my friends here in Southern 
> California.   The universal report was very muffled, restricted and only 
> marginally intelligible audio, the same results I remember from the last time 
> I played with a throat mic back in the 50s.   
> My question here is, was there a particular communication technique, method 
> of articulation, special vocabulary, etc., which had to be used with these 
> things?    Hard to believe they were satisfactory for operational use.

Heh, heh, you noticed that too, Dennis?  <g>  This is probably as good a 
point as any to quote the 1946 Summary Technical Report of the National 
Defense Research Committee Division 17:

"9.2.3 Throat Microphones

A device used widely by the USAAF at the beginning of WWII was the 
throat microphone.  In this assembly the microphone is strapped to the 
throat directly above the larynx.  Such an arrangement possessed the 
advantage of apparently low noise pickup and free use of hands, and it 
probably would have been a very effective instrument but for the fact 
that the speech signal available at the larynx is intrinsically 
unintelligible."

Those last two words pretty much sum it up.  :-)  It goes on to say this 
was not caused by a basic design flaw, since British and captured 
Japanese throat mikes showed the same problem on structured 
intelligibility tests.  The shift to oxygen mask mikes (and others) was 
in part a reaction the the throat mike problem.  There are some 
interesting intelligibility curves for different mike configurations, 
with the old T-17 very close to the top of the heap.  My personal 
favorite (if you want an 'authentic' WWII hands-free aircraft 
microphone) is the H-46 boom mike headset, which was an AAF derivative 
of the T-45 ground force lip mike.  There's a picture of one of mine at 
http://members.cox.net/mymhh/H-46_vs_H-63.JPG, contrasted with the 
later, fairly common H-63 headset mike that happens to fit the H-46 
holder on the side of the earphones.

Best 73,
Mike