Monica A. McHenry

Aerodynamic, acoustic, and perceptual measures of nasality following traumatic brain injury

Data were obtained from 31 subjects who had incurred a traumatic brain injury (TBI). Two expert listeners judged nasality using direct magnitude estimation with a referent. They rated samples of the first sentence of the Rainbow Passage, played backwards, with all pauses removed. Sensitivity was good for nasalance, velopharyngeal airway resistance, and velopharyngeal orifice area, indicating that these measures would accurately identify an individual as nasal. Specificity was reduced, and was adequate only for nasalance. The reduced specificity was due to a high number of false positives, i.e. perceived nasality in the absence of objective corroboration. Analysis of the false positives revealed that a slow speaking rate could mislead a listeners perception of nasality. Overall, for individuals with dysarthria following TBI, the measure of nasalance may most accurately reflect listener perception of nasality.

The Effect of Increased Vocal Effort on Estimated Velopharyngeal Orifice Area

Velopharyngeal deficits are a common component of dysarthria following neurogenic insults. Compensatory strategies may minimize the impact of velopharyngeal deficits on speech production. Velophary...

The challenge of unintelligible speech following traumatic brain injury

Management of unintelligible speech following traumatic brain injury is complex. In addition to multiple physiological system deficits, individuals typically present with complicating non-speech factors that impede their progress. The present case study illustrates the influence on outcome of impaired speech physiology, reduced cognitive abilities, pre-morbid personality characteristics, and psychosocial variables such as post-injury psychosis. Highlighted intervention strategies include optimizing the physiological system with a palatal lift prosthesis, reducing speaking rate by pacing, phonetically transcribing words to minimize apraxia of speech, adapting stimuli to optimize auditory comprehension, and providing therapy within functional contexts.

Acoustic characteristics of voice after severe traumatic brain injury.

Objectives/Hypothesis To describe the acoustic characteristics of voice in individuals with motor speech disorders after traumatic brain injury (TBI).

Brain–computer interfaces increase whole-brain signal to noise

Brain–computer interfaces (BCIs) can convert mental states into signals to drive real-world devices, but it is not known if a given covert task is the same when performed with and without BCI-based control. Using a BCI likely involves additional cognitive processes, such as multitasking, attention, and conflict monitoring. In addition, it is challenging to measure the quality of covert task performance. We used whole-brain classifier-based real-time functional MRI to address these issues, because the method provides both classifier-based maps to examine the neural requirements of BCI and classification accuracy to quantify the quality of task performance. Subjects performed a covert counting task at fast and slow rates to control a visual interface. Compared with the same task when viewing but not controlling the interface, we observed that being in control of a BCI improved task classification of fast and slow counting states. Additional BCI control increased subjects’ whole-brain signal-to-noise ratio compared with the absence of control. The neural pattern for control consisted of a positive network comprised of dorsal parietal and frontal regions and the anterior insula of the right hemisphere as well as an expansive negative network of regions. These findings suggest that real-time functional MRI can serve as a platform for exploring information processing and frontoparietal and insula network-based regulation of whole-brain task signal-to-noise ratio.

Neurofeedback of two motor functions using supervised learning-based real-time functional magnetic resonance imaging

This study examines the effects of neurofeedback provided by support vector machine (SVM) classification-based real-time functional magnetic resonance imaging (rt-fMRI) during two types of motor tasks. This approach also enables the examination of the neural regions associated with predicting mental states in different domains of motor control, which is critical to further our understanding of normal and impaired function. Healthy volunteers (n = 3D13) performed both a simple button tapping task, and a covert rate-of-speech counting task. The average prediction accuracy was approximately 95% for the button tapping task and 86% for the speech task. However, subsequent offline analysis revealed that classification of the initial runs was significantly lower - 75% (p<0.001) for button and 72% (p<0.005) for speech. To explore this effect, a group analysis was performed using the spatial maps derived from the SVM models, which showed significant differences between the two fMRI runs. One possible explanation for the difference in spatial patterns and the asymmetry in the prediction accuracies is that when subjects are actively engaged in the task (i.e. when they are trying to control a computer interface), they are generating stronger BOLD responses in terms of both intensity and spatial extent.

The vocal health of auctioneers.

A questionnaire designed to assess vocal demands and vocal health was completed by 438 randomly selected auctioneers. Over 96% reported using amplification to auction the majority of the time. A greater proportion of individuals who auctioned in environments with poor air quality visited a physician for a voice problem than individuals who auctioned in environments with clean air. Significant contributors to vocal quality changes and vocal fatigue were frequency of auctioning, as well as auctioning in noise. In addition, the duration of auctioning without a break significantly contributed to vocal fatigue. Vocal hygiene recommendations are provided based on these findings.

Vital capacity following traumatic brain injury

This study was designed to describe lung volume subdivisions in individuals with traumatic brain injury. Records were reviewed for 114 consecutive referrals for motor speech evaluations in a community re-entry residential rehabilitation programme. Obtained measures were vital capacity, inspiratory capacity, and expiratory reserve volume at the time of evaluation. Seventy-nine per cent of subjects evidenced at least moderate deficits in expiratory reserve volume, with 60% evidencing severe deficits. Inspiratory capacity was the least affected, with 61% of subjects evidencing values within normal limits. Possible contributors to reduced expiratory reserve volumes include expiratory muscle weakness due to physical inactivity, inability to voluntarily perform the task, or perceived effort.

Differential activity of the pars recta and pars oblique infundamental frequency control

This study was designed to determine if differences exist in pars recta and pars oblique muscle activity during speech and singing. Hooked wire electrodes were implanted in the muscle bundles under direct vision during thyroid surgery in two men and three women. It was found that the pars recta and pars oblique do not function in a similar manner across fundamental frequencies (fos), tasks, or subjects. Large inter- and intrasubject variability was evident in the contribution of the cricothyroid bundles to fundamental frequency (fo) control. It is speculated that the effect of pars recta and pars oblique contraction may be a function of individual anatomic variations.

Comparison of direct and indirect calculations of laryngeal airway resistance in various voicing conditions

Calculation of laryngeal airway resistance using intraoral pressure divided by airflow has become a widely accepted clinical tool. The estimation is based largely on theoretical assumptions, particularly regarding the relationship between intraoral and subglottal pressure. To determine the estimates validity, direct measures of airflow and subglottal, intraoral and pharyngeal pressures were obtained for four men and four women. Subjects produced normal, loud, soft and simulated breathy and strained syllable trains. Comparison of direct and indirect calculations of laryngeal airway resistance revealed generally good correspondence, particularly for [pi] syllables, although the estimates accuracy varied among individual subjects. Some interpretive caution is warranted for the extremes of laryngeal airway resistance, with resistance likely to be underestimated in the strained condition, and overestimated in the breathy condition.