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   rec.audio.tech      Theoretical, factual, and DIY topics in      41,683 messages   

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   Message 40,841 of 41,683   
   Jamie M to josephkk   
   Re: noise canceling headphones   
   27 Jan 12 18:34:56   
   
   XPost: sci.electronics.design   
   From: jmorken@shaw.ca   
      
   On 1/26/2012 11:27 PM, josephkk wrote:   
   > On Wed, 25 Jan 2012 17:12:40 -0800, Jamie M  wrote:   
   >   
   >> On 1/23/2012 10:03 PM, josephkk wrote:   
   >>> Not to be too much of a jerk, but just exactly how to you disambiguate the   
   >>> received noise signal from the reflected corrective signal?   
   >>>   
   >>   
   >> Hi,   
   >>   
   >> Turn off the drive signal and listen periodically, like a sensorless   
   >> BLDC motor maybe?   
   >>   
   >> cheers,   
   >> Jamie   
   >   
   >   
   > Think that through really carefully.  What would be the user response to   
   > that?   
      
   Hi,   
      
   Ok maybe a better idea is to do a continuous FFT of the actual   
   headphone voltages and then compare this to the "desired" FFT from the   
   digital audio signal (ie MP3) and then generate a correction signal to   
   adjust the output voltage.   
      
   cheers,   
   Jamie   
      
      
   >   
   > ?-)   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   

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