PROBLEM TO BE SOLVED: To clearly auralize information based on a relationship between a plurality of muscular activities.SOLUTION: A sound signal is output, the sound signal representing a strain degree being at least any one of a relative value between a muscle activity degree corresponding to a muscle potential of an agonist muscle and a muscle activity degree corresponding to a muscle potential of an antagonist muscle corresponding to the agonist muscle, and variation of a relative value between a muscle activity degree corresponding to a muscle potential of an agonist muscle and a muscle activity degree corresponding to a muscle potential of an antagonist muscle. The sound signal approaching a specific sound signal as an order relationship of a plurality of muscles at an activity start time point approaches an appropriate order relationship or for a set composed of an agonist muscle and antagonist muscle is output as a signal of a channel different for each set.SELECTED DRAWING: Figure 1