AUDITORY CUES FOR ORIENTATION AND POSTURAL CONTROL IN SIGHTED AND CONGENITALLY BLIND PEOPLE

This study assessed whether stationary auditory information could affe ct body and head sway (as does visual and haptic information) in sight ed and congenitally blind people. Two speakers, one placed adjacent to each ear, significantly stabilized center-of-foot-pressure sway in a tandem Romberg stance, while neither a single speaker in front of subj ects nor a head-mounted sonar device reduced center-of-pressure sway. Center-of-pressure sway was reduced to the same level in the two-speak er condition for sighted and blind subjects. Both groups also evidence d reduced head sway in the two-speaker condition, although blind subje cts' head sway was significantly larger than that of sighted subjects. The advantage of the two-speaker condition was probably attributable to the nature of distance compared with directional auditory informati on. The results rule out a deficit model of spatial hearing in blind p eople and are consistent with one version of a compensation model. Ana lysis of maximum cross-correlations between center-of-pressure and hea d sway, and associated time lags suggest that blind and sighted people may use different sensorimotor strategies to achieve stability.