Communication Science and Disorders electronic theses and dissertations (MU)
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The items in this collection are the theses and dissertations written by students of the Department of Communication Science and Disorders. Some items may be viewed only by members of the University of Missouri System and/or University of Missouri-Columbia. Click on one of the browse buttons above for a complete listing of the works.
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Item Individual variability in maternal infant-directed speech(University of Missouri--Columbia, 2023) Mahajani, Riya; Smith, Nicholas A.Infant-directed speech (IDS) is a universal, distinctive way in which adults speak to infants. IDS is characterized by a higher and more variable voice pitch, slower rate of speech, shorter utterances, more repetition, longer pauses, and increased simplification. This study examined acoustical differences between IDS and adult-directed speech (ADS) in terms of mean and median pitch, and pitch variability during play interactions between 42 mother-infant dyads. Also, this study examined individual variability in the degree of pitch enhancement done by mothers in IDS as compared to their own ADS. Finally, this study investigated the potential relation between individual difference in maternal sensitivity and differences in maternal IDS. The results indicated significantly higher mean and median pitches, and a significantly more pitch variability in IDS as compared to ADS. Despite individual variability in the degree to which mothers enhanced their speech while interacting with infants, no significant correlation was found between maternal sensitivity and acoustic measures of IDS pitch.Item Effects of menthol on swallowing function in a mouse model of presbyphagia(University of Missouri--Columbia, 2016) Littrell, Loren Leigh; Lever, Teresa E.[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] The goal of this study was to characterize the progression of presbyphagia in our recently established mouse model and investigate the treatment effect of menthol on swallow dysfunction in advanced aging mice. To accomplish these goals, we evaluated a total of 17 advanced-age (i.e., late senescent) C57BL/6 mice (22-25 months; 9 males, 8 females) using our freely-behaving videofluoroscopic swallow study (VFSS) protocol. Three test solutions were administered at room temperature in the following order, spaced 30 minutes apart: standard VFSS recipe, standard VFSS recipe + 5 mM menthol, and standard VFSS recipe. Video recordings were analyzed to quantify the immediate and potentiation (30 minute) effects of menthol. Swallow function in late senescent mice was significantly more impaired than young mice. Oral ingestion of 5 mM menthol had immediate and potentiation effects on all three stages of swallowing. Specifically, menthol resulted in significantly (p<0.05) faster lick rates, higher lick-swallow ratios, longer inter-swallow intervals, slower swallow rates, faster esophageal transit times, higher proportion of effective esophageal swallows, and fewer swallows required to clear the esophagus. This study provides novel evidence that menthol "rescues" swallow function, returning it to youthful levels. A larger scale pre-clinical study is underway to systematically investigate the therapeutic efficacy and safety of menthol as a treatment strategy for presbyphagia/dysphagia in mice and to elucidate the responsible molecular mechanisms of action.Item Word learning from context : relations with language ability, socioeconomic status, and executive function(University of Missouri--Columbia, 2017) Hill, Margaret, 1963-; Wagovich, Stacy A.During the school-age years, children learn most new word meanings from context rather than through deliberate vocabulary instruction. However, the actual process of word learning from context among schoolage children remains poorly understood. Prior research suggests that language ability and higher-order executive function skills such as working memory and inhibitory control of attention may aid children in acquiring new word meanings from context, but studies have not examined the effect of cognitive flexibility on word learning. In addition, although research has shown that children from families of low socioeconomic status (SES) often lag behind their peers from higher-SES backgrounds in vocabulary, there is no evidence to suggest that SES directly influences the word learning process itself. The purpose of this study was to examine the effects of language ability, SES, and executive function on word learning from context among typically developing children. Fifty children of ages nine to 11 years completed a standardized measure of language ability and tasks of working memory, inhibitory control, and cognitive flexibility along with a pretest to assess their understanding of 12 rare target words. Approximately one week later, the children read along with two short stories containing the target words while listening as the stories were narrated aloud by a computer. Posttest results showed that as a group, children made small but significant gains in knowledge of target word meanings from the stories. Analyses showed that both language ability and cognitive flexibility were related to gains in word knowledge, and that children tended to rely more on the stronger of these two skills if either language or cognitive flexibility was relatively weak. Children's SES backgrounds were not directly related to word knowledge gains, but results suggested that SES may influence the word learning process indirectly through an effect on children's cognitive flexibility.Item The effect of laryngeal nerve transection on swallowing function in a mouse model(University of Missouri--Columbia, 2017) Mok, Alexis Ann; Lever, Teresa E.Dysphagia is a common postoperative complication of cervical and thoracic surgical procedures, presumably caused by iatrogenic laryngeal nerve injury. It is unknown which laryngeal nerve contributes most to dysphagia and poor medical outcomes after injury. To address this clinically relevant question, we used our established Videofluoroscopic Swallow Study (VFSS) assay to objectively assess swallow function and our established laryngoscopy assay to assess vocal fold (VF) mobility after surgically-induced (iatrogenic) laryngeal nerve injury in a mouse model. C57BL/6J mice (n=31) underwent unilateral transection of the superior or recurrent laryngeal nerves (SLN or RLN) or a sham surgery. Swallowing was assessed through VFSS and VF mobility was assessed through laryngoscopy pre-surgery and several timepoints post-surgery. We validated our surgical procedure by confirming that our surgical technique itself was not negatively impacting swallow function or VF mobility. Unilateral SLN transection did not result in acute or chronic dysphagia or VF immobility, whereas unilateral RLN transection resulted in acute dysphagia and ipsilateral VF paralysis; dysphagia did not persist long-term, whereas VF paralysis did. SLN versus RLN transection produced different dysphagia profiles in our mouse model. In the future, we plan to use this model as a platform to investigate the pathophysiology of post-surgical dysphagia and to explore potential treatments.Item A multiple subsystem approach to predicting speech intelligibility declines in older adults(University of Missouri--Columbia, 2017) McKinley, Jacob; Dietrich, Maria (Maria M.),; Kuruvilla-Dugdale, Mili S.Introduction: Given the significant impact of progressive dysarthrias on individuals’ communication abilities and the increasing prevalence of progressive dysarthrias in the United States, it is becoming imperative to develop prediction models of speech intelligibility decline. As a first step, the present study focused on healthy older adults and specifically, on determining age-related effects on the respiratory, phonatory, and articulatory subsystems and their impact on speech intelligibility. For this purpose, we used a multiple subsystem approach similar to that used in the extant literature on cerebral palsy (Lee, Hustad, & Weismer, 2013) and amyotrophic lateral sclerosis (ALS; Rong et al., 2016). The aims of the present study were to (1) determine age-related changes to the respiratory, phonatory, and articulatory subsystems and (2) investigate whether speech intelligibility decline is observed in healthy older adults and if so, to determine which variables from each subsystem are predictive of intelligibility decline. Method: Fifteen healthy, older adults and fifteen younger adults participated in instrument-based assessments of the phonatory, respiratory, and articulatory subsystems. Respiratory, acoustic, aerodynamic, and kinematic measures were obtained during syllable, sentence, word, and nonspeech tasks. Speech intelligibility for each speaker was determined by naïve listeners during multi-talker babble. Contributions of selected subsystem variables on speech intelligibility were determined using a multiple linear regression analysis. Results: Age-related differences were detected across phonatory and articulatory subsystem measures including maximum phonation time and cepstral peak prominence (phonatory subsystem) and spatiotemporal variability index and maximum speed of tongue movements (articulatory subsystem). Selected variables in the phonatory and articulatory subsystem were significant predictors of speech intelligibility in older adults including laryngeal airway resistance (39%), airflow during voicing (35%), maximum phonation time (9%; phonatory subsystem) and duration (10%) and maximum speed (5%) of tongue movements (articulatory subsystem). Collectively, 98% of speech intelligibility variance in older adults could be explained by the phonatory (83%) and articulatory (15%) subsystem models. Discussion: Significant subsystem differences between older and younger adults were found indicating age-related speech decline. Measures representing phonatory and articulatory subsystems predicted speech intelligibility differences in older adults suggesting that age-related speech declines such as breathy voice quality and age-related articulatory slowing contributed to intelligibility decline. Subsystem measures were more sensitive to age-related speech differences in older adults than intelligibility, which is a finding consistent in ALS literature (Ball, Willis, Beukelman, & Pattee, 2001; Green et al., 2013).