The design of CAST (Computer-Aided Speechreading Training)

The underlying theoretical assumptions, goals, design, and implementation of a Computer-Aided Speechreading Training system (CAST) are described as a case study in program design. This computerized speechreading assessment and training system simulates face-to-face intervention and is designed to be one component of a comprehensive aural rehabilitation program for preretirement adults with acquired mild-to-moderate hearing loss. The interactive, automated course consists of eight training lessons, each focusing on a particular viseme that is practiced by a modified discourse tracking method using viseme-specific texts. Three basic speechreading skills are emphasized: visual speech perception, use of linguistic redundancy, and use of feedback between message sender and receiver. These skills are evaluated separately by means of CAST tracking rate, receiver strategy, and inferred error type. Four example case assessments are provided to illustrate the potential applications of CAST as a standardizable rehabilitative tool. An independent program evaluation is provided in a companion paper (Gagné, Dinon, & Parsons, 1991). Comparisons between CAST, face-to-face tracking procedures, and natural discourse are presented and discussed with reference to theoretical and clinical issues in speechreading and program evaluation.