Sonification of Rotation Instructions to Support Navigation of People with Visual Impairment

Indoor navigation services for people with visual impairment are being researched in academia, and working systems have already been deployed in public places. While previous research mainly focuses on computing the user's position with high accuracy, providing non-visual navigation instructions is also a challenge and naive approaches can fail in helping users reach their target destination or even expose them to hazards. In this paper we investigate the problem of guiding users to rotate towards a target direction. We propose three different sonification techniques that provide continuous guidance during rotation, and we compare them to a single-impulse baseline, used in previous works. We also explore three variations that reinforce the proposed techniques by combining them with the baseline. A preliminary study with 10 blind participants highlights two dominant techniques, which we analyze through a follow-up study with 18 participants, from 2 groups with very distant cultural backgrounds. While stark differences emerge in the performance from the two groups, we highlight two clear results common to both: 1) one of the proposed techniques significantly outperforms the baseline, reducing the average rotation error by a factor of 3.5 (from 11° to 3°); 2) the interaction speed of this technique, generally slower than the baseline, significantly improves when combined with the baseline technique.