The use of myoelectric feedback in teaching facial expression to the blind

Five blind subjects were provided with an auditory "mirror" of their facial activity by transducing myoelectric signals from facial muscles into sound. Expressions of happiness, surprise, and anger were defined primarily by involvement of the zygomaticus, the frontalis, and the corrugator, respectively. These muscles were connected through separate voltage-controlled oscilllators to separate loudspeakers, such that each muscle activated a different speaker. Motion pictures taken before and after training were assembled in random order and were shown to preselected judges who attempted to identify the expressions. The judges were correct significantly more often on the posttraining expressions. Appropriateness and adequacy of expressions, as rated by the judges, also improved significantly as a result of training.