[RFI] New Interference at kk0sd

[Jim Brown]

There is a LOT of great advice in this post, but I'll zero in on this 
one, on the basis of my professional background in psychoacoustics (the 
science of how our brains process what we hear). There's a fundamental 
property of human hearing behind the success of what Ed describes. Human 
hearing is FAR more able to hear differences in the loudness of one 
sound compared to the other when they are more nearly equal. The two 
sounds here were the arcing sound and the broadband circuit noise.

Also, we humans have very poor sensitivity to the loudness of a sound. 
It takes a change of 6-10 dB for us to perceive a sound as twice as loud 
(or half as loud), but a change of only 1-2 dB in the strength of a 
signal that is very close to the noise level can be the difference copy 
or no copy. And when I was recording mixing live sound for a jazz band, 
I rarely needed to move faders more than a dB or two once I had the mix 
"right" musically.

73, Jim K9YC

On 3/23/2021 11:27 PM, Hare, Ed, W1RFI wrote:
> I had a step attenuator, so I decided to try a trick. I drove to about where I thought it was strongest. I listended to the raucous buzz (120 Hz) and cranked in attentuation until the buzz dissapeared and all I heard was white noise from the receiver. I cranked back until I could JUST barely hear the buzz over the white noise of the receiver.  My ear was pretty good at that.  I again drove the line and heard it louder as I drove past a