[ARC5] NDRC & Aircraft Audio above 20,000 Ft

[Richard Knoppow]

    I found an article describing the development of the throat mic at:
http://americanradiohistory.com/Archive-Communications-Magazine/1940s/Communications-1943-01.pdf
    My reference is from "Acoustical Engineering" Harry F. Olson. He 
also has citations in more academic journals but I can't access them on 
the web.
    He also cites an article in the "Bell Labs Record" which is available at
http://americanradiohistory.com/Archive-Bell-Laboratories-Record/40s/Bell-Laboratories-Record-1945-06.pdf

     This describes the development of military headphones and 
microphones including the throat mic and lip mics and the mics fitted 
into oxygen masks and also the ear bud type headphone mentioned earlier 
in this thread. It is quite comprehensive.
     Modern aircraft headsets are mostly of the "boom" type with the 
microphone on a short stalk which can be placed close to the mouth. This 
can obviously not be used with an oxygen mask but except for military 
aircraft they are not often used.
    The lip type microphone and most of the boom mics are of the 
differential type which discriminate against background noise. The 
discrimination is wavelength dependent and is larger for lower 
frequencies. The high frequency discrimination being due mainly to 
proximity to the source (mouth).
      The article on the throat mic as well as Dr. Olson's notes on it, 
suggest the problems were well known at the time of its design but it 
seemed to be the best solution to a difficult problem available. The 
article in "Communications" suggests it was also used in industrial 
applications such as by welders who had to wear face masks.
     The home site at Americanradiohistory. com has an enormous amount 
of material on it and is bookmark worthy.

On 9/23/2017 11:31 AM, Kenneth G. Gordon wrote:
> On 23 Sep 2017 at 13:15, David Stinson wrote:
> 
>>      Then there´s the "Mustache Mic" that hung from your ears with a
>>      couple of loops,  ran across your face above your upper lip
>>      with the element under your nose, looking like a  "Hitler" mustache.
>>       I read that the things were treated with some kind of
>>      jungle fungus stuff that stank unbearably and, if worn in
>>      a hot environment, sweat leached-out the chemical
>>      and caused a nasty, itchy rash from ear-to-ear.
>>      Sometimes, ya can´t win for losing...
> 
> I had one of those once, which I got with a brand-new BC-1000 from MARS. Didn't think too
> much of it...
> 
> Ken W7EKB


-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL