Sound, central auditory nervous system function and human gait: the effect of quiet and localized sound sources on the gait of people with normal and atypical central auditory nervous system function

Abstract

A kinematic gait analysis system was used to determine the 3-D motion of human gait under varying sound conditions. This analysis was conducted in nine adults with normal central auditory nervous system (CANS) function (Group1), and nine adults with CANS dysfunction (Group2). The analysis was completed with reduced lighting in a semi-anechoic chamber fitted with five speakers around the calibrated gait area. Seven sound cases were presented to each subject: for five localized sound (LS) inputs, muffed under a reduced sound (RS) condition, and natural walking under RS. The objectives of this study were to (1) quantify the gait and head movement of people in Group1 and Group2, (2) determine the difference of the gait between the groups induced by localized sound sources, and (3) demonstrate the correlation between Central Auditory Processing Test Battery diagnosis and the gait of Group2. This study found that the gait in both groups is affected by the presence of sound. In going from RS to LS, both groups have opposite responses. For RS, Group1 reduces walking speed and stride width while lowering the head towards the chest when compared to LS. Group2, in contrast, increases stance width, and walking speed, and lowers the head more for RS than for LS. Group2 was also found to have a wider variance in head nod than Group1. This study found that the drifting of the center of mass (COM) in the lateral (Z) direction for Group2 changes significantly under LS. Interestingly, two subgroups within Group2 have different COM movement dependent upon the diagnosis of weak-ear. Also, the movement of the head in the transverse plane was found to be significantly different between Group1 and Group2 for RS versus LS. This study was the first to show the difference in gait between groups of people based upon CANS function. Furthermore, the reduced visual stimuli of this study may have emphasized the impact of the localized sound input on human gait. This research helps set parameters for forthcoming studies into the effect of sound on human motor function.