[Elecraft] Noise Cancelling Headphones

[Phil Kane]

On 12/26/2013 11:02 AM, Jim Brown wrote:

> Successful noise cancelling requires that the resulting acoustic output
> AS COUPLED TO THE EAR CANAL precisely match the acoustic noise that GETS
> THROUGH THE HEADPHONES TO THE EAR CANAL (caps added for emphasis) in
> both magnitude and phase, and that the two acoustic signals are out of
> polarity. That means that the mic picking up the noise be very close to
> the headphones, the distance between the mic, the transducer, and the
> ear must be compensated, and the relative response, both magnitude and
> phase, must be precisely compensated.  That's a VERY difficult design
> problem, and a really good solution is only practical when everything is
> built as an integrated package, with dedicated mic, headphone
> transducers, and electronics.

That, and the miniaturization and customization involved, is why my
hearing assistance devices (high-end Phonak behind-the ear hearing aids)
cost $3000 per ear.

I have yet to try conventional large-cuff headphones since I got those
aids three plus years ago.  I use a streaming audio adapter that
Bluetooth-couples to the aids.  It doesn't solve the noise problem but
is more comfortable.

That works with my K2 just fine!  For data modes (RTTY/PSK/SITOR) I work
"quiet room" (RX AF volume at minimum) and use the waterfall as my
tuning aid.
-- 
73 de K2ASP - Phil Kane
Elecraft K2/100   s/n 5402

>From a Clearing in the Silicon Forest
Beaverton (Washington County) Oregon