Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!tinman.cis.ohio-state.edu!bob From: bob@tinman.cis.ohio-state.edu (Bob Sutterfield) Newsgroups: comp.protocols.tcp-ip Subject: Re: human factors aspects of echo delay Message-ID: Date: 7 May 89 19:30:02 GMT References: <8905041101.aa24075@huey.udel.edu> <15965@bellcore.bellcore.com> Sender: news@tut.cis.ohio-state.edu Organization: The Ohio State University Dept of Computer & Information Science Lines: 27 In-reply-to: karn@ka9q.bellcore.com's message of 7 May 89 05:38:20 GMT Though delayed sidetone (feedback of one's own speech through headphones) is tough on an individual, delayed full-duplex vocal transmission causes all sorts of new social conventions to arise. I've held conversations over circuits that the telephone company generously routed via satellite, even though the call only went between Columbus and Boston. None of the normal socially-induced timings that we Americans use to decide when the other person is done speaking seemed to work, because we'd both jump into the silence at the same time that we heard the other person start speaking. This caused lots of awkward backoffs and retries until we figured out what was happening. At first, I just figured it was normal east-cost asocial rudeness :-) The line quality was good enough that we couldn't tell from the transmission carrier itself whether the other person had "lifted his thumb from the mike". So we both, fairly naturally it turned out, fell back into the old half-duplex radio conventions of terminating each thought-chunk with "Over". This got us through several calls in the course of a week and finally that vendor's hardware and my backplane were happy with each other. The other people in the office got quite a kick out of overhearing my side of the conversation. Perhaps this means that interactive clients and servers will need better characters-per-packet batching algorithms for higher-delay networks, with local half-duplex feedback and appropriate "I'm done now" signals on both ends...