[Elecraft] Copying CW and Pitch
Chris R. NW6V
chrisrut7 at gmail.com
Sun Mar 14 19:11:09 EDT 2021
On Sat, Mar 13, 2021 at 5:45 PM Jim Brown <jim at audiosystemsgroup.com> wrote:
> On 3/13/2021 10:48 AM, Sverre Holm (LA3ZA) wrote:
> > A CW sidetone pitch of 400 Hz is consistent with what little research
> there
> > is on this. A paper from 1992 says that "/All subjects improved their
> > recognition as the frequency was lowered to 500 Hz, some even at 250 Hz.
>
> As a retired designer of large sound systems, I had to learn a lot about
> acoustics and psychoacoustics (the science of how humans' ear/brain
> interprets what we hear). That science tells us that, like most of our
> senses, hearing is logarithmic both with respect to frequency and
> loudness. This means that our discrimination of one frequency as
> compared to another increases with decreasing frequency. That is, we are
> better able to separate signals from each other with RX pitch set to
> lower frequencies.
>
> 73, Jim K9YC
Exactly right.
I have screaming-loud tinnitus at 1700hz - which is louder than
conversation, and rises and falls in pitch and volume with every
heartbeat... Fun, fun.
Changing sidetone from 800 to 400 made a HUGE difference in my ability to
copy through the chaos. I did so after reading an article 2 or 3 years ago
- perhaps those referenced, but I thought it was done by the USAF for
intercept operators in the late 60's - I may be mistaken.
ut for those who might not get the implications of what Jim said: our
perceptions depend less on absolute values than on the difference between
two values. That's why when you get "hot" with a fever, you "feel cold"
(and want heat, blankets, etc.): the outside air is now "colder" with
respect to your skin temp.
In terms of Morse, if the signal you're listening to is at 800 Hz, and the
interfering signal (or even the tone of the white noise) is at 700 Hz, the
100hz difference amounts to just 12%. However, if the desired signal is at
400 Hz, and the interfering signal at 300, that 100hz difference is now
25%. At 300/200, it's 50%. Bigger differences are easier to copy.
I did have to reprogram myself to listen at the lower frequency -
familiarity had bred contentment.
73 Chris NW6V
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