Different effects of auditory feedback in man- machine interfaces

Two experiments were carried out to estimate the effect of sound feedback (e.g., auditory alarms) on the operator's work of a man-machine system. The first experiment tested the hypothesis of additional, but redundant auditory feedback. Twelve subjects were instructed to define queries on a simple database. In this experiment, we could not find a general superiority of auditory feedback. In a second experiment we designed a process simulator so that each of eight machines made tones to indicate its hidden status over time. Eight students of computer science operated this process simulation program of an assembly line with robots. Relevant information of disturbances and machine breakdowns was given in auditory forms, too. The results indicate, that the additional feedback of auditory alarms improves significantly the operator performance and increases positively some mood aspects.