Optimum distance for voice navigation in walking support system for visually impaired

Voice navigation with information and communication technologies allows the visually impaired (VI) to grasp the current situation promptly. While instruction prior to the action e.g. turning a corner, seems to be effective, the optimum lead distance remains unclear. This paper verifies experimentally the optimum lead distance to support VI while walking. In the experiment, each subject (normal vision) walked while wearing an eye mask to simulate VI, holding a white cane, and received voice guidance. After each trial, the subject scored the lead distance in terms of acceptability. 28 young healthy males/females participated. Results showed the highest score was for 3 m while the lowest was for 5 m. Distance range with score over 3 (average) was 2 to 4 m. No clear significant difference was observed in terms of subject height. As walking speed was around 0.55 m/s, 1 m was deemed insufficient. 5 m or more seemed to be too long as subjects failed to predict accurately how far they had moved. This experiment verified that VI voice navigation turn instructions are effective if given more than 1m and less than 4 m before the turning point