Subjective evaluation of transmission delay in telephone conversations

An earlier experiment by Riesz and Klemmer on the effect of pure-transmission delay upon natural telephone conversations was extended in a test with more than double the time period and number of calls. The previous finding of little or no adverse reaction to round-trip pure delays of 600 and 1200 msec alone was confirmed. The previous finding of a large increase in dissatisfaction with both of these delays following exposure to 2400 msec was not obtained. Exposure to delays of 2400 msec led to no dissatisfaction with later calls at 600 msec, but some rejections at 1200 msec did occur. There is no contradiction of other results on normal telephone circuits with 2-wire terminations (and related echo sources, paths, and suppressors) wherein customer dissatisfaction is greater with 600 msec delay than with the much shorter delay of a normal long-distance circuit.