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 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
