Customer Evaluation of Telephone Circuits with Delay

In 1964 tests were begun in which customers making transatlantic calls, to which varying amounts of delay had been added, were interviewed after call completion to determine the circuit quality. These tests were continued in 1965 using the Early Bird satellite which some customers used extensively before being interviewed. During this period a number of different echo suppressors were also tested. Results show that the quality of telephone circuits with echo suppressors decreases with increasing delay, that previous satellite calls have no effect on the customer's opinion of his present call, and that no echo suppressor was superior for all delays although some appear to be better for the longer delays.