We recently showed that congenitally blind adults have severely impaired thresholds in an auditory spatial bisection task, pointing to the importance of vision in constructing auditory spatial maps. To explore strategies that may improve the auditory spatial sense of the blind, we investigated the impact of tactile feedback on spatial auditory localization in 29 blindfolded sighted subjects, assigned at random to one of three groups: tactile feedback (n=11), verbal feedback (n=8) and no feedback (n=10). For all groups, auditory bisection thresholds were first measured by playing three consecutive sounds at 500 ms intervals, and subjects judged whether the second sound was spatially closer to the first or to the third. The tactile-feedback group was given two audio-tactile training sessions of 100 trials, where each auditory trial was followed by the same spatial sequence played on the subject’s forearm; auditory spatial bisection thresholds were evaluated after each session. The no-feedback group did the same sequence of trials, with no feedback. In the verbal-feedback condition, the positions of the sounds was verbally reported to the subject after each training trial. Interestingly, subject performance improved significantly only after the audio-tactile training, on average by a factor of 2.5. The no-feedback sessions, and those with verbal feedback produced no statistically significant improvement. The results suggest that direct tactile feedback interacts with the auditory spatial localization system, possibly by a process of cross-sensory recalibration. More generally, the results encourage the possibility of designing rehabilitation programs to help blind individuals establish a robust sense of space.

tactile; audio; recalibration; spatial localization