Re: [Bloat] DSLReports Speed Test has latency measurement built-in

[David Lang <david@lang.hm>]

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On Tue, 28 Apr 2015, Rich Brown wrote:

> On Apr 28, 2015, at 4:38 AM, Sebastian Moeller <moeller0@gmx.de> wrote:
>
>> 	Well, what I want to see is a study, preferably psychophysics not modeling ;), showing the different latency “tolerances” of humans. I am certain that humans can adjust to even dozens of seconds de;ays if need be, but the goal should be fluent and seamless conversation not interleaved monologues. Thanks for giving a bound for jitter, do you have any reference for perceptional jitter thresholds or some such?
>
> An anecdote (we don't need no stinkin' studies :-)
>
> I frequently listen to the same interview on NPR twice: first at say, 6:20 am when the news is breaking, and then at the 8:20am rebroadcast.
>
> The first interview is live, sometimes with significant satellite delays between the two parties. The sound quality is fine. But the pauses between question and answer (waiting for the satellite propagation) sometimes make the responder seem a little "slow witted" - as if they have to struggle to compose their response.
>
> But the rebroadcast gets "tuned up" by NPR audio folks, and those pauses get edited out. I was amazed how the conversation takes on a completely different flavor: any negative impression goes away without that latency.
>
> So, what lesson do I learn from this? Pure latency *does* affect the nature of the conversation - it may not be fluent and seamless if there's a satellite link's worth of latency involved.
>
> Although not being exhibited in this case, I can believe that jitter plays worse havoc on a conversation. I'll also bet that induced latency is a good proxy for jitter.

satellite round trip latency is on the order of 1 second, which is at the far 
end of what can be tolerated for VoIP.

Go back to the '80s and '90s when the phone companies were looking at converting 
from POTS long-distance lines to digital (with ATM) and there was a lot of work 
done at the time about voice communication and what 'sounds good'. This is a lot 
fo what drove the ATM design, predictable latency.

David Lang