Psychological Evaluation of Telephone Switching and Transmission Performance

Abstract

In order to set standards for the performance of the telephone network, it is necessary to understand the subjective effects of the telephone service impairments we wish to control. In a laboratory environment, we asked subjects to play a computer-controlled game which required the frequent use of the telephone as a natural part of the game. Impairments to telephone switching service, such as dial-tone delay, post-dialing delay, and blocked call attempts, and impairments to telephone transmission quality, such as loss and noise were introduced into the telephone service which the subjects experienced. After each use of the telephone, the subjects rendered their opinion, on a five-point rating scale, as to the quality of telephone service just provided.

The data produced by the experiment were used to construct a mathematical model of customer opinion as a function of the objective measures of telephone network performance. This model will enable us to analyze the present performance of the telephone system. More importantly, the model will enable us to estimate customer opinion for future telephone systems, were we to implement new or revised standards for the control of switching and transmission impairments.