[Elecraft] K3S Noise reduction Test

[wa9fvp]

Jim Brown Wrote
 
EXACTLY RIGHT!  The scientific study of how we hear and perceive sound 
is called psychoacoustics, and is one of many important disciplines of 
the Acoustical Society of America. Early work at Bell Labs and at 
universities like MIT and Harvard became the basis for stereo. 

Some of the first published work was by Joseph Henry, whose name is on 
the unit of inductance in recognition of his invention of meters and 
motors. It was Henry who first observed (around 1850) that when the same 
sound is heard from two directions, the one that arrives first at our 
ears tells us where the sound is coming from. This fact is the basis of 
the Bell Labs stereo patent, and makes it far superior to the Blumlein 
work published a year or so earlier. 



 
I remember something from the telecom days and I found this on the Internet.
 
"The lowest discernible signal that can be heard by a human being is -90 dBm
(800 or 1000 Hz)"
 
It brings back something I heard in the early days when DSP noise reduction
was first introduced to Ham Radio.  At one of the Dayton Hamvention
seminars, I don't remember who that was, they said something to the affect
"Noise reduction cannot pull an SSB signal out of the noise. It can however
reduce the noise floor to a comfortable listing level'.  I guess, that's all
we can hope for.
 
PS; In order to reduce bandwidth, I try to cut previous posting from my
replies. Sometimes I forget and for that I apologies. 
--
Jack WA9FVP


 




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Jack WA9FVP

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