[CQ-Contest] Advice Sought for Wireless Headsets & Mics

Jim Brown k9yc at audiosystemsgroup.com
Fri Dec 4 20:41:07 EST 2015

On Fri,12/4/2015 12:04 PM, David Pruett wrote:
> During 30+ years in the automotive industry, we had a rule of thumb 
> that anything under 100 mS couldn't be "noticed" by the human operator. 

Human tolerance of delay is VERY dependent on the application. With 
AUDIO, an echo greater than about 35 msec becomes increasingly 
problematic; even delays as short at 30 msec can be fatiguing. Increase 
the delay to 80 msec, and the talker will slow down and stop talking. In 
my live sound work, I've witnessed VERY professional announcers turn to 
silly putty when hearing themselves coming through a ballpark sound 
system 100 msec after their speech.

The problem occurs with the talker hears him/herself coming through 
distant loudspeakers, producing the delay. There are two very effective 
fixes. 1) Prevent them from hearing themselves on delay; or 2) give them 
their voice UN-delayed in headphones.

I have not seen studies, nor have I experienced, latency beyond about 10 
msec or so ham applications, but I would expect anything much beyond 100 
msec to get tricky in a contesting application, simply because you're 
giving away that much reaction time. Also, remember that our systems are 
two-way, so TX and RX delays are additive.

I'd love to hear a thoughtful, analytical presentation/discussion by 
some top contesters who have dealt with latency in high rate contesting. 
I think it would VERY educational.

73, Jim K9YC

73, Jim K9YC

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