Length of Time Before Seven Pairs of Talkers Could Detect 1.2 Seconds of Delay PAIRS OF TALKERS NUMBER OF SECONDS BEFORE TALKERS DETECTED DELAY G/H 161 224 107 F/K 87 65 43 220 false alarm A/L 618 95 367 F/T no detection after 954 seconds S/H 227 false alarm 90 75 83 K/G 38 421 20 143 S/W 257 229 no detection after 260 seconds [Illustration: _Data from table have been arranged in this histogram to show wide range of delay detection times that were recorded in the experiment. Each block represents a single delay detection, identified by initials of conversers._] number of cases 6 S/H 5 S/H 4 S/H S/W 3 K/G A/L S/H 2 K/G F/K K/G F/K 1 F/K F/K G/H G/H S/W A/L K/G A/L 0 0 50 100 150 200 250 300 350 400 450 500 550 600 650 detection time (seconds) Now, to answer our question about whether people can converse over our circuit, we can say something like this: We have found some cases (of a certain type of conversation) where people _can_ use a circuit with 1.2 seconds of echo-free delay for the amounts of time listed in our table. But there are two important things to remember about our results: —_The findings are a_ non-negative _answer to the original question, “Can people converse over a four-wire, echo-free circuit that has delay like that of a synchronous satellite?”_ —_The experiment applies_ only _to four-wire, echo-free circuits, and does not help with the problem of improving echo suppressors or with that of finding out how good synchronous satellite circuits with the best possible echo suppressors would be if they were used to interconnect the world’s telephones._