Communication Sciences and Disorders Commons^™

Hydration And Vocal Loading On Voice Measures, Anusha Sundarrajan

Open Access Dissertations

Vocal loading adversely affects the healthy larynx. The negative effects of vocal loading are thought to be exacerbated in dry environments, noisy environments, using non-habitual speaking patterns, and voice quality. Advancing age is also thought to be a risk factor for the negative effects of loading. To systematically tease out the effects of these factors on the healthy larynx, three different experiments were conducted. In each experiment, healthy participants produced 45-minutes of child-directed speech. In experiment 1, older, healthy adults produced loud child-directed speech, in the presence of background noise, in both low and moderate humidities, and voice was assessed. …

Neural Activity Reveals Effects Of Aging On Inhibitory Processes During Word Retrieval, Ranjini Mohan

Open Access Dissertations

Word retrieval difficulties are one of the most frustrating problems in older adults. Poorer access to phonological (speech sound) representation of the target word has been postulated as the underlying deficit, supported by findings of improvement in word retrieval after phonological priming. But the great variability in naming performance among older adults may reflect cognitive scaffolding or compensatory neurophysiological processes related to maintenance or decline of naming abilities. In order better understand aging effects in the underlying neurophysiological changes associated with phonological retrieval, the present study examined electrophysiological correlates of phonological priming and word retrieval in adults across the lifespan. …

Current Steering And Electrode Spanning With Partial Tripolar Stimulation Mode In Cochlear Implants, Ching-Chih Wu

Open Access Dissertations

Cochlear implants (CIs) partially restore hearing sensation to profoundly deaf people by electrically stimulating the surviving auditory neurons. However, CI users perform poorly in challenging listening tasks such as speech recognition in noise and Cochlear implants (CIs) partially restore hearing sensation to profoundly deaf people by electrically stimulating the surviving auditory neurons. However, CI users perform poorly in challenging listening tasks such as speech recognition in noise and music perception, possibly due to the small number of implanted electrodes and the large current spread of electric stimulation. Although current spread may be reduced using partial tripolar (pTP) stimulation mode, the …

Effects Of Hearing Aid Amplification On Robust Neural Coding Of Speech, Jonathan Daniel Boley

Open Access Dissertations

Hearing aids are able to restore some hearing abilities for people with auditory impairments, but background noise remains a significant problem. Unfortunately, we know very little about how speech is encoded in the auditory system, particularly in impaired systems with prosthetic amplifiers. There is growing evidence that relative timing in the neural signals (known as spatiotemporal coding) is important for speech perception, but there is little research that relates spatiotemporal coding and hearing aid amplification.

This research uses a combination of computational modeling and physiological experiments to characterize how hearing aids affect vowel coding in noise at the level of …

Developing A Drug Delivery System For Treatment Of Vocal Fold Scarring, Aaron Michael Kosinski

Open Access Dissertations

Vocal fold scarring is an affliction that results in the formation of a disorganized and stiff extracellular matrix (ECM) with abnormal ECM component densities & structures including a significant increase in collagen deposition. It is caused by improper healing post injury and results in profound changes in the biomechanical properties of the vocal folds impairing their ability to generate a normal mucosal wave during phonation.

Finding an effective treatment for vocal fold scarring has been elusive. Currently, treatments seek temporary solutions that correct glottal incompetence and reduce stiffness caused by the scar through the augmentation of the vocal folds using …

Predicting Language Impairment Status: A Risk Factor Model, Johanna Maria Rudolph

Open Access Dissertations

The etiology of specific language impairment (SLI) is multifactorial. Research has shown that genetic, environmental, and developmental factors may influence the course of its development. Because many of these factors are present even before a child is born, it is possible that a child's risk of developing the disorder can be identified long before grammatical deficits are observed. The goal of this study was to develop and validate a screening tool to discriminate between children with SLI and typically developing (TD) children using risk factor information including gender, family history of communication or reading disorders, socioeconomic status, maternal and paternal …

Neural Encoding Of Complex Signals In The Healthy And Impaired Auditory Systems, Saradha Ananthakrishnan

Open Access Dissertations

Individuals with sensorineural hearing loss (SNHL) typically experience difficulty in understanding speech. Our current knowledge of deficits in speech perception and encoding consequent to SNHL is restricted to psychophysical studies in humans and single-unit experiments in animals. However, the nature of degradation in neural encoding of speech following hearing impairment in humans has not been extensively researched. The objective of this dissertation is to provide a systematic evaluation of neurobiological signature of hearing loss at the subcortical level using an objective electrophysiological non-invasive neural index, the frequency following response (FFR). Subcortical neural encoding of speech signals is explored by quantifying …