The purpose of this study was to determine the effect of augmentative visual feedback training on auditory-motor performance. Thirty-two healthy young participants used facial surface electromyography (sEMG) to control a human-machine interface (HMI) for which the output was vowel synthesis. An auditory-only (AO) group (n=16) trained with auditory feedback alone and an auditory-visual (AV) group (n=16) trained with auditory feedback and progressively-removed visual feedback. Subjects participated in three training sessions and one testing session over three days. During the testing session they were given novel targets to test auditory-motor generalization. We hypothesized that the auditory-visual group would perform better on the novel set of targets than the group that trained with auditory feedback only. Analysis of variance on the percentage of total targets reached indicated a significant interaction between group and session: individuals in the AV group performed significantly better than those in the AO group during early training sessions (while using visual feedback), but no difference was seen between the two groups during later sessions. Results suggest that augmentative visual feedback during training does not improve auditory-motor performance.

The purpose of this study was to determine the effect of age on visuomotor tracking using submental and anterior neck surface electromyography (sEMG) to assess feasibility of computer control via neck musculature, which allows people with little remaining motor function to interact with computers. Thirty-two healthy adults participated: sixteen younger adults aged 18 – 29 years and sixteen older adults aged 69 – 85 years. Participants modulated sEMG to achieve targets presented at different amplitudes using real-time visual feedback. Root-mean-squared (RMS) error was used to quantify tracking performance. RMS error was increased for older adults relative to younger adults. Older adults demonstrated more RMS error than younger adults as a function of increasing target amplitude. The differential effects of age found on static tracking performance in anterior neck musculature suggest more difficult translation of human-computer-interfaces controlled using anterior neck musculature for static tasks to older populations.

Objective High voice users (individuals who demonstrate excessive or loud vocal use) are at risk for developing voice disorders. The objective of this study was to examine, both acoustically and perceptually, vocal changes in healthy speakers following an acute period of high voice use. Methods Members of a university women’s volleyball team (N=12) were recorded a week prior (Pre) and week following (Post) the 10-week spring season; N=6 control speakers were recorded over the same time period for comparison. Speakers read four sentences, which were analyzed for relative fundamental frequency (RFF). Eight naïve listeners participated in an auditory-perceptual visual sort and rate (VSR) task, in which they rated each voice sample’s overall severity and strain. Results No significant differences were found as a function of time point in the VSR ratings for the volleyball group. Onset cycle 1 RFF values were significantly lower (p = 0.04) in the Post recordings of the volleyball participants compared to Pre recordings, but there was no significant difference (p = 0.20) in offset cycle 10 RFF values. Receiver operating characteristic analyses indicated moderate sensitivity and specificity of onset cycle 1 RFF for discrimination between the volleyball and control participants. Changes were not apparent in the control group as a function of time for either, onset cycle 1 RFF, offset cycle 10 FF, or either vocal attribute. Conclusion Onset cycle 1 RFF may be an effective marker for detecting vocal changes over an acute high voice use period of time before perceptual changes are noted.

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The purpose of this study was to evaluate the effect of augmentative visual feedback training on performance using auditory feedback alone for human-machine interface (HMI) control. Sixteen healthy participants used bilateral facial surface electromyography to achieve two-dimensional control to reach vowel targets. Eight participants trained with combined visual and auditory feedback, while eight participants trained with real-time auditory feedback only. Each subject participated in four sessions over three days; three sessions with their designated feedback modality (auditory only or auditory with supplementary visual) and a fourth session on the third day using novel vowel targets to test generalization of auditory-motor learning. Analyses of variance performed on the percentage of total targets reached demonstrated a main effect of group and the interaction of group and session. Individuals provided with augmentative visual feedback during training outperformed individuals using auditory feedback alone in initial training sessions. However, training with augmentative visual feedback had no effect on individuals' training and generalization performance using auditory feedback alone after three days of training.