UMD Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/3
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.
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Item THE ROLE OF READING COMPREHENSION IN LARGE-SCALE SUBJECT-MATTER ASSESSMENTS(2013) Zhang, Ting; Torney-Purta, Judith; Human Development; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This study was designed with the overall goal of understanding how difficulties in reading comprehension are associated with early adolescents' performance in large-scale assessments in subject domains including science and civic-related social studies. The current study extended previous research by taking a cognition-centered approach based on the Evidence-Centered Design (ECD) framework and by using U.S. data from four large-scale subject-matter assessments: the IEA TIMSS Science Study of 1999, IEA CIVED Civic Education Study of 1999, and the 1970s IEA Six Subject surveys in Science, and in Civic Education. Using multiple-choice items from the TIMSS science and CIVED tests, the study identified a list of linguistic features that contribute to item difficulty of subject-matter assessments through the Coh-Metrix software, human rating, and multiple regression analysis. These linguistic features include word length, word frequency, word abstractness, intentional verbs, negative expressions, and logical connectives. They pertain to different levels of Kintsch's reading comprehension model: surface level, textbase level, and situation model. Integrating this item-level information into multiple regression analysis and Multidimensional IRT modeling, the study provided feasible methods (1) to estimate reading demand of test items in each subject-matter assessment, and (2) to partial out variance related to high level of reading demand of some test items and independent of the domain proficiencies that the subject-matter assessment was intended to measure. Overall, results suggested that reading demands of all test items in TIMSS Science and CIVED tests were within the reading capabilities of almost all of the students, and these two tests were not saturated with high reading demand. In addition, multiple regression results from the earlier Six Subject Surveys showed that an independent measure of students' general vocabulary was highly correlated with their achievement in the domains of science and civic-related social studies. On average, boys outperformed girls in both subject domains, and students from home with ample literacy resources outperformed students from homes of few literacy resources. In the science assessment, interactions were found between gender and word knowledge, home literacy resources and word knowledge, meaning the correlation between vocabulary and science performances differed by gender and home background.Item The benefits of acoustic input to combined electric and contralateral acoustic hearing(2008-08-01) Zhang, Ting; Gordan-Salant, Sandra; Dorman, Michael F.; Hearing and Speech Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)With the extension of cochlear implant candidacy, more and more cochlear-implant listeners fitted with a traditional-long electrode array or a partial-insertion electrode array have residual acoustic hearing either in the nonimplanted ear or in both ears and have shown to receive significant speech-perception benefits from the low-frequency acoustic information provided by residual acoustic hearing. The aim of Experiment 1 was to assess the minimum amount of low-frequency acoustic information that was required to achieve speech-perception benefits both in quiet and in noise from combined electric and contralateral acoustic stimulation (EAS). Speech-recognition performance of consonant-nucleus vowel-consonant (CNC) words in quiet and AzBio sentences in a competing babble noise at +10 dB SNR was evaluated in nine cochlear-implant subjects with residual acoustic hearing in the nonimplanted ear in three listening conditions: acoustic stimulation alone, electric stimulation alone, and combined contralateral EAS. The results showed that adding low-frequency acoustic information to electrically stimulated information led to an overall improvement in speech-recognition performance for both words in quiet and sentences in noise. This improvement was observed even when the acoustic information was limited down to 125 Hz, suggesting that the benefits were primarily due to the voice-pitch information provided by residual acoustic hearing. A further improvement in speech-recognition performance was also observed for sentences in noise, suggesting that part of the improvement in performance was likely due to the improved spectral representation of the first formant. The aims of Experiments 2 and 3 were to investigate the underlying psychophysical mechanisms of the contribution of the acoustic input to electric hearing. Temporal Modulation Transfer Functions (TMTFs) and Spectral Modulation Transfer Functions (SMTFs) were measured in three stimulation conditions: acoustic stimulation alone, electric stimulation alone, and combined contralateral EAS. The results showed that the temporal resolution of acoustic hearing was as good as that of electric hearing and the spectral resolution of acoustic hearing was better than that of electric hearing, suggesting that the speech-perception benefits were attributable to the normal temporal resolution and the better spectral resolution of residual acoustic hearing. The present dissertation research provided important information about the benefits of low-frequency acoustic input added to electric hearing in cochlear-implant listeners with some residual hearing. The overall results reinforced the importance of preserving residual acoustic hearing in cochlear-implant listeners.