The role of sensory feedback on the coordination dynamics of a limb and a voice task.

다국어 초록 (Multilingual Abstract)

Although it is generally acknowledged that sensory feedback is required to fine tune movement patterns, its role in coordinative dynamics has received less attention. Experiment 1 investigated the role of visual and auditory feedback on 0° and 180° relative phase patterns at increasing frequency of oscillation for a bimanual limb task. The dependent variables were mean error of relative phase and standard deviation of relative phase. Results indicated that the visual and auditory feedback conditions did not influence the accuracy and the variability in performance of the 2 relative phase patterns, whereas increasing frequency influenced the performance of the 180° relative phase pattern, but not the 0° relative phase pattern. Experiment 2 investigated the role of auditory feedback on breathy, normal, and pressed voice qualities at increasing fundamental frequency for a voice coordination task. The dependent variables were mean of laryngeal resistance (cmH2O/l/s) and standard deviation of laryngeal resistance (cmH2O/l/s). Results indicated that the masked auditory feedback condition significantly increased variability in performance across all 3 voice qualities and specifically, the masked auditory feedback condition facilitated significantly higher mean laryngeal resistance values for the pressed voice quality but not for the breathy and the normal voice qualities. As a potential explanation of the current findings in Experiment 1, it is hypothesized that the bimanual coordination task did not rely on visual and auditory feedback because the task was governed by proprioceptive feedback, which was not controlled in the present study. For Experiment 2, sensory feedback may be relevant for voice patterns that have a shallow basin of attraction (i.e., pressed voice), but irrelevant for voice patterns that have a steep basin of attraction (i.e., breathy and normal voice). Perhaps the breathy and normal voice qualities were governed by voice coordination dynamics, while the pressed voice quality was partly influenced by auditory feedback connections. In addition, level of expertise may also play a role in the coordination dynamics of a voice task. The influence of auditory feedback on voice coordination dynamics suggests an expanded view of dynamic systems theory and supports the role of auditory feedback in vocal rehabilitation.