Automatic evaluation of time-varying communication systems

Many types of speech-communication systems may be readily evaluated with available electronic devices which employ the concept of the Articulation Index. To study the feasibility of using such devices to evaluate time-varying systems, recordings were made of the transmission characteristics of a troposphere-scatter system. At many specific points in time in these recordings, Articulation Indexes were calculated, and intelligibility scores were obtained from listeners with the aid of a special test procedure. For most points, the intelligibility score could be reasonably well predicted from the Articulation Index. This finding was interpreted as indicating that the existing devices are potentially capable of evaluating time-varying systems.