Effect of age on human-computer-interface control via neck electromyography.

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.

Effects of Adventitious Acute Vocal Trauma: Relative Fundamental Frequency and Listener Perception.

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 after an acute period of high voice use. METHODS: Members of a university women's volleyball team (n = 12) were recorded a week before (pre) and week after (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 postrecordings of the volleyball participants compared with prerecordings, 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 RFF, or either vocal attribute. CONCLUSIONS: 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.

Visuomotor control of neck surface electromyography in Parkinson's disease.

OBJECTIVE: To compare performance of individuals with Parkinson's disease (PD) and age-matched controls on a visuomotor tracking task controlled via surface electromyography (sEMG). METHODS: Twenty-seven adults with PD and twenty-four older controls produced dry swallows and completed a visuomotor tracking task utilizing both static and dynamic targets. sEMG was recorded at the anterior neck and submental surface during both tasks. RESULTS: There was no significant difference in visuomotor tracking ability between cohorts. Post hoc analyses indicated that there was no significant difference between participant groups in the strength or duration of swallows as measured by sEMG but that participants with PD showed a trend for decreased swallow durations at the anterior neck (padj = 0.067) whereas controls showed a trend for increased durations at the anterior neck (padj = 0.112), compared to the submental surface. However, there were no significant correlations between swallowing behavior and visuomotor tracking ability. CONCLUSION: There were no significant differences in visuomotor tracking performance between individuals with PD and controls. Furthermore, there was no relationship between tracking ability and swallowing behavior. We conclude that sEMG-mediated biofeedback may have limited promise as a tool for treating PD-related dysphagia.

Effects of augmentative visual training on audio-motor mapping.

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 3days. 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 role of augmentative visual training in auditory human-machine-interface performance.

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.

Effects of Parkinson's Disease on Fundamental Frequency Variability in Running Speech.

In Parkinson's Disease (PD), qualitative speech changes such as decreased variation in pitch and loudness are common, but quantitative vocal changes are not well documented. The variability of fundamental frequency (F0) in 32 individuals (23 male) with PD both ON and OFF levodopa medication was compared with 32 age-matched healthy controls (23 male). Participants read a single paragraph and estimates of fundamental frequency (F0) variability were determined for the entire reading passage as well as for the first and last sentences of the passage separately. F0 variability was significantly increased in controls relative to both PD groups and PD patients showed significantly higher F0 variability while ON medication relative to OFF. No significant effect of group was seen in the change in F0 variability from the beginning to the end of the reading passage. Female speakers were found to have higher F0 variability than males. F0 variability was both significantly reduced in PD relative to controls and significantly increased in patients with PD during use of dopaminergic medications. F0 variability changes over the course of reading a paragraph may not be indicative of PD but rather dependent on non-disease factors such as the linguistic characteristics of the text.