stodol@diku.dk (David Stodolsky) (02/10/90)
[Reposted from comp.dcom.telecom (TELECOM Digest)] Message-ID: <2284@accuvax.nwu.edu> Date: 20 Dec 89 00:11:47 GMT Sender: news@accuvax.nwu.edu Organization: TELECOM Digest Lines: 51 Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 9, Issue 584, message 1 of 10 goldstein@delni.enet.dec.com in <2002@accuvax.nwu.edu> writes >Funny you should ask. Yes, there's a new ISDN 7 kHz audio bearer >service. It makes use of 64 kbps ADPCM encoding. Mermelstein, P., (1988). G.722, A New CCITT Coding Standard for Digital Transmission of Wideband Audio Signals (IEEE Communications Magazine, v. 26, n. 1) describes a way to split audio input into two 4 khz bands using ADPCM coders. Audio data can be transmitted at 64, 56, or 48 kbits, thus allowing simultaneous transmission of other data. The system is targeted toward "audio- visual conferencing applications where one would like to approach the quality of face-to-face communication (p. 8)." My interest, is not the improvement in audio quality, but the use of data-speech multiplexing. This is projected in the article, for speaker identification or fax on the established connection. One of the major problems in teleconferencing is speaker selection, how to decide on the next speaker without using the normal cues one has when face-to-face. The Danish Telecommunication Research Labs. produced a pre-ISDN prototype with separate lines for audio, and speaker id and queuing data via modem, some years back. It turned out to be too complex for practical use. A version of my equal-time resolution rule was programmed into that system (Stodolsky, D. (1987). Dialogue management program for the Apple II computer. _Behavior Research Methods, Instruments, & Computers_, _19_, 483484.). This rule has been show to yield benefits in both emotional tone and group performance in controlled experiments. I would like to see the rule applied in one of these new ISDN conferencing systems, but its hard to get the attention of the equipment suppliers on this point. They typically resort to centralized control by a chairmen, without even the ability to run on "auto pilot", where people queue themselves up by pressing a "request" button or just by starting to talk with a voice-operated switch "pressing" the button for them. Central control of speakers was strongly disliked in the prototype system. In fact, all units were eventually rebuilt, so each one could be the "master" in a multi-unit conference. Chairmen management seemed a bit clumsy, even when the queuing was automatic and the chair just announced the name of the next speaker. From a psychological standpoint, fully distributed control is the only way to go, and it is quite feasible with ISDN, any takers? -- David S. Stodolsky, PhD Internet: david@harald.ruc.dk Department of Psychology : stodol@diku.dk Copenhagen Univ., Njalsg. 88 Voice: + 45 31 58 48 86 DK-2300 Copenhagen S, Denmark Fax: + 45 31 54 32 11