[Elecraft] Echo and feedback un SSB

[Jim Brown]

On 4/20/2014 4:16 PM, Dave Hachadorian wrote:
> I can't hear any delay in the K3 monitor, and I am VERY sensitive to 
> that.

I have the capability to measure it, but I have not done so. If it's 
going through any DSP, there will be some, probably a few msec. I would 
not expect it to be a problem.

The difference between what we hear through bone conduction and the 
actual sound of our voice is mostly the difference in frequency response 
between the two paths.

We can get a better approximation of how we sound to others by talking 
straight into a hard wall at a very close distance. Now, our ears hear 
our voice bouncing off that wall with very little loss.

There's a phenomenon called "precedence effect" that was first 
documented by Joseph Henry around 1850 (the guy whose name is on the 
unit of inductance in recognition of his inventions involving magnetics 
much earlier). Precedence effect describes the characteristic of human 
hearing that if we hear the same sound from more than one direction, we 
will "hear" it as a single sound, coming from the direction from which 
it arrives FIRST even though a later arrival is louder. There's a limit 
-- a loudness difference of more than 10 dB will "break" precedence.

Yes, long delayed echoes can make it difficult to talk or to play music. 
In live sound reinforcement, delays are produced by DSP, and also by the 
time it takes sound to get from speakers over a stage down to the 
audience. Delays more than about 35 msec will start causing fatigue or 
discomfort, and I've heard very professional announcers slow down and 
stop talking with delays in the 80-100 msec range.

73, Jim K9YC