[Elecraft] [K3] Hearing aids, meet K3

[Jim Brown]

On 8/7/2013 10:40 AM, Alan Jump wrote:
> As I recall from my broadcasting classes years ago, human speech has a
> "typical" bandwidth of just 3KHz. "Normal" human hearing, IIRC, picks up
> frequencies from 20Hz to 20KHz.
>
> If someone has a copy of Schrader's "Electronic Communications" ready to
> hand, the specifics should be in there somewhere.

Not quite -- audio and acoustics professionals know that there are 
components of human speech from around 100 Hz to 10 kHz. What IS correct 
is that audio bandwidth of about 500 Hz to 3 kHz is entirely sufficient 
for good speech intelligibility. Bell Labs, the R & D arm of AT&T, and 
the greatest such lab on the planet for the first 80 or so years of the 
20th century, learned this more than 100 years ago. Extending bandwidth 
at both ends makes the voice more natural, and usually more pleasing, 
and extending highs to 5-6 kHz improves intelligibility slightly, but 
extending lows often hurts intelligibility.

73, Jim K9YC