[ICOM] re: speaker filter (or Headset ?)

[Sheldon Daitch]

OK, and that brings up a technical question regarding
the typical inexpensive noise canceling headphones used
on aircraft, not the pilot style headsets, but those used
with the entertainment systems.  The audio is a T-R-S
1/8 inch which matches normal consumer grade audio headsets.
But the noise canceling side uses a T-R-S plug, slightly
smaller than that 1/8 inch audio plug/jack.  

There is a small time delay between the time the headset
is plugged into the dual jacks in the armrest, and the
time the headset goes into the noise canceling mode, but
the noise canceling on/off is instantaneous with the
on/off switch in the entertainment control unit.

So, the question is, what is the pin-out for the audio
noise canceling portion of one of these headsets.  Obviously
they are powered by the aircraft entertainment system, but
can also be controlled from the entertainment system.  

I've done a Google and I can find a lot of information on
the self contained units, like Bose, but nothing on the
airline supplied units.

Any ideas?

Thanks,

73
Sheldon
WA4MZZ

"David J. Ring, Jr." wrote:
> 
> The "noise canceling" headphones sold by Bose and most others only cancel
> noise in the room.  They do NOT cancel noise on the audio signal to the
> headphones.
> 
> To cancel noise on the audio signal, some sort of receiver filtering, or add
> on DSP must be used.
> 
> The Bose is a totally different animal.
> 
> 73
> DR
> ----- Original Message -----
> From: "Malcolm Ringel" <mringel at bluecrab.org>
> To: "ICOM Reflector" <icom at mailman.qth.net>
> Sent: Thursday, September 09, 2004 3:29 PM
> Subject: Re: [ICOM] re: speaker filter (or Headset ?)
> 
> The original question referred to speakers and/or headphones. I wonder if
> anyone here has used their Icom (!) xcvr with a set of the so-called
> "noise-canceling" headphones, such as those recently offered by Bose.
> Malcolm, K3KZ
> ----- Original Message -----
> From: <aa7zc at bendbroadband.com>
> To: "'ICOM Reflector'" <icom at mailman.qth.net>
> Sent: Wednesday, September 08, 2004 8:45 PM
> Subject: RE: [ICOM] re: speaker filter