A Clinical Tool for Assessing Infants' Auditory Acuity

poster abstractMy translational research involves developing tools to assess speech perception and language skills during infancy. Language assessment during infancy helps identify children who are at risk for language disorders so that they can receive appropriate intervention as soon as possible. It also allows speech-language pathologists and other clinicians evaluate the success of their therapy and intervention strategies

Effects of congenital hearing loss and cochlear implantation on audiovisual speech perception in infants and children

Purpose: Cochlear implantation has recently become available as an intervention strategy for young children with profound hearing impairment. In fact, infants as young as 6 months are now receiving cochlear implants (CIs), and even younger infants are being fitted with hearing aids (HAs). Because early audiovisual experience may be important for normal development of speech perception, it is important to investigate the effects of a period of auditory deprivation and amplification type on multimodal perceptual processes of infants and children. The purpose of this study was to investigate audiovisual perception skills in normal-hearing (NH) infants and children and deaf infants and children with CIs and HAs of similar chronological ages. Methods: We used an Intermodal Preferential Looking Paradigm to present the same woman\u27s face articulating two words ( judge and back ) in temporal synchrony on two sides of a TV monitor, along with an auditory presentation of one of the words. Results: The results showed that NH infants and children spontaneously matched auditory and visual information in spoken words; deaf infants and children with HAs did not integrate the audiovisual information; and deaf infants and children with CIs initially did not initially integrate the audiovisual information but gradually matched the auditory and visual information in spoken words. Conclusions: These results suggest that a period of auditory deprivation affects multimodal perceptual processes that may begin to develop normally after several months of auditory experience

Hearing versus Listening: Attention to Speech and Its Role in Language Acquisition in Deaf Infants with Cochlear Implants

The advent of cochlear implantation has provided thousands of deaf infants and children access to speech and the opportunity to learn spoken language. Whether or not deaf infants successfully learn spoken language after implantation may depend in part on the extent to which they listen to speech rather than just hear it. We explore this question by examining the role that attention to speech plays in early language development according to a prominent model of infant speech perception – Jusczyk’s WRAPSA model – and by reviewing the kinds of speech input that maintains normal-hearing infants’ attention. We then review recent findings suggesting that cochlear-implanted infants’ attention to speech is reduced compared to normal-hearing infants and that speech input to these infants differs from input to infants with normal hearing. Finally, we discuss possible roles attention to speech may play on deaf children’s language acquisition after cochlear implantation in light of these findings and predictions from Jusczyk’s WRAPSA model

Molecular systematics and phylogeography of the genus Richardsonius

The complex geological and climatic events that significantly altered the landscape throughout the Cenozoic Era impacted the diversification of many North American taxa, including freshwater fishes. Here, I employ an array of phylogenetic analyses using a multiple gene tree approach to address several questions regarding the phylogenetic relationships of the North American cyprinid genus Richardsonius and two other closely related genera, Clinostomus and Iotichthys. I also use divergence time estimates generated using fossil calibrations to qualitatively assess the phylogeographic implications of evolution within and among these three genera. Mitochondrial and nuclear DNA sequences show a sister relationship between Iotichthys and Richardsonius, with Clinostomus being sister to an Iotichthys - Richardsonius clade. Therefore, the currently recognized sister relationship between Clinostomus and Richardsonius is not supported by my analyses. The genera Clinostomus, Iotichthys, and Richardsonius appear to be monophyletic lineages, and the two species within Richardsonius, R. balteatus and R. egregius, appear to be reciprocally monophyletic sister species. Richardsonius balteatus and R. egregius both exhibit phylogeographic structure, and I examined phylogeographic structure within R. egregius using molecular phylogenetic and population genetic methods. Divergence time estimates between genera and species are Miocene and Pliocene in age respectively, and divergence between phylogroups within R. balteatus and R. egregius occurred in the late Pliocene to Pleistocene. Splits between genera and species coincide with documented geological and climatic events, and the deepest divergence within R. egregius appears to have been influenced more by Pliocene or early Pleistocene events than by more recent drainage patterns associated with the latest glacial maxima of the Pleistocene Epoch. Contemporary migration does not appear to occur between eastern and western Lahontan Basin populations

Essays on understanding post-secondary preparation and matriculation of high school students relative to differential public school contexts

This study includes consists of three essays in which I demonstrate that high school contexts are related to the postsecondary preparation, entrance, and matriculation of high school students, particularly for underrepresented populations. My inquiry utilizes comprehensive state longitudinal data, nationally representative longitudinal data, and national school fiscal data, along with quantitative methods to examine these relationships. The dissertation relies on two statistical methods and two unique data sources. Utilizing multilevel modeling and state longitudinal data, the first paper examines the results of school funding policies and the extent to which school funding is related to the postsecondary preparation and matriculation of students. The results suggest that per-pupil revenue is related to an increase in ACT math scores, likelihood of four-year post-secondary enrollment, and four-year post-secondary degree attainment. Utilizing the same Illinois high school data and propensity-score matching techniques, the second paper explores the relationship between a high school’s average teacher quality and the postsecondary preparation and matriculation of students identified as Black and Latino. The findings indicate that, for Black and Latino students that attended schools with above-average or higher teachers, ACT math scores are higher and the likelihood of enrollment in a four-year post-secondary institution is greater. Finally, utilizing a nationally representative sample of data from the Educational Longitudinal Study of 2002 (ELS:02), supplemented with Common Core Data, and propensity-score matching, the third paper examines the extent to which the intersection of student socioeconomic status and school quality is related to post-secondary matriculation. For students identified as being from a low socioeconomic background, attending a higher quality school is related to an increase in the likelihood for both two- and four-year post-secondary enrollment. Taken together, the three essays provide further evidence that increases in school resources, whether it be funding, teachers, or in general, are related to educational achievement, and, more specifically, the likelihood of underrepresented students advancing to and progressing through post-secondary institutions

Language skills of profoundly deaf children who received cochlear implants under 12 months of age: a preliminary study

Conclusion. This study demonstrated that children who receive a cochlear implant below the age of 2 years obtain higher mean receptive and expressive language scores than children implanted over the age of 2 years. Objective. The purpose of this study was to compare the receptive and expressive language skills of children who received a cochlear implant before 1 year of age to the language skills of children who received an implant between 1 and 3 years of age. Subjects and methods. Standardized language measures, the Reynell Developmental Language Scale (RDLS) and the Preschool Language Scale (PLS), were used to assess the receptive and expressive language skills of 91 children who received an implant before their third birthday. Results. The mean receptive and expressive language scores for the RDLS and the PLS were slightly higher for the children who were implanted below the age of 2 years compared with the children who were implanted over 2 years old. For the PLS, both the receptive and expressive mean standard scores decreased with increasing age at implantation

Transcriptome-Facilitated Development of SNPs for the Sonoran Desert Rock Fig, Ficus petiolaris (Moraceae)

Premise of the study: Single-nucleotide polymorphism (SNP) primers were developed for a native North American desert fig, Ficus petiolaris (Moraceae), to provide markers for population genetic studies designed to quantify patterns of gene flow across a complex landscape. Methods and Results: Transcriptome sequencing and bioinformatic protocols were implemented to discover SNPs in single-copy protein-coding genes. Multiplexes of 30 nuclear and 24 organellar (chloroplast and mitochondrial) SNPs were selected for primer development and genotyping on the Sequenom MASSArray System. Of these 54 loci, 49 reliably amplified across a panel of 96 F. petiolaris individuals. Conclusions: This study has provided SNP primers that can be applied in future studies investigating population genetics of F. petiolaris and its coevolution with associated pollinating and nonpollinating fig wasps

The Role of Early Intervention in Parental Self-Efficacy for Parents of Deaf and Hard-of-Hearing Children

Purpose: To investigate the effects of age at enrollment in early intervention (EI) and dosage of EI services (frequency and intensity) on parental self-efficacy (PSE) and to determine whether parents with better PSE demonstrate more involvement in deciding Individualized Family Service Plan goals (IFSP), services, and amount of services. Method: Sixty-five parent-child dyads were included in this retrospective between-subjects study. PSE was measured using the Scale of Parental Involvement and Self-Efficacy (DesJardin, 2003). Dosage of EI services and parent/professional involvement in IFSP decision-making were measured using a Child Demographic Questionnaire. Results: Statistically significant correlations were not found between age at EI enrollment and SPISE subscales. Statistically significant correlations were not found based on frequency or intensity of EI services. Mixed results were found regarding level of parent involvement in decision-making of IFSP goals, kinds of services, and amount of services. Conclusions: Findings demonstrate the complexities in determining the effects of age at EI enrollment, EI dosage, and central elements of the IFSP on self-efficacy in parents of children who are deaf/hard-of-hearing. Future studies are needed to validate these findings and further the knowledge base about the role of EI in supporting parents’ sense of self-efficacy in supporting their child’s development

Vowel discrimination by hearing infants as a function of number of spectral channels

Reduced spectral resolution negatively impacts speech perception, particularly perception of vowels and consonant place. This study assessed impact of number of spectral channels on vowel discrimination by 6-month-old infants with normal hearing by comparing three listening conditions: Unprocessed speech, 32 channels, and 16 channels. Auditory stimuli (/ti/ and /ta/) were spectrally reduced using a noiseband vocoder and presented to infants with normal hearing via visual habituation. Results supported a significant effect of number of channels on vowel discrimination by 6-month-old infants. No differences emerged between unprocessed and 32-channel conditions in which infants looked longer during novel stimulus trials (i.e., discrimination). The 16-channel condition yielded a significantly different pattern: Infants demonstrated no significant difference in looking time to familiar vs novel stimulus trials, suggesting infants cannot discriminate /ti/ and /ta/ with only 16 channels. Results support effects of spectral resolution on vowel discrimination. Relative to published reports, young infants need more spectral detail than older children and adults to perceive spectrally degraded speech. Results have implications for development of perception by infants with hearing loss who receive auditory prostheses