Hearing & Speech Sciences Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2776
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Item SPECTRAL CONTRASTS PRODUCED BY CHILDREN WITH COCHLEAR IMPLANTS: INVESTIGATING THE IMPACT OF SIGNAL DEGRADATION ON SPEECH ACQUISITION(2022) Johnson, Allison Ann; Edwards, Jan; Hearing and Speech Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The primary objective of this dissertation was to assess four consonants, /t/, /k/, /s/, and /ʃ/, produced by young children with cochlear implants (CIs). These consonants were chosen because they comprise two place-of-articulation contrasts, which are cued auditorily by spectral information in English, and they cover both early-acquired (/t/, /k/) and late-acquired (/s/, /ʃ/) manners of articulation. Thus, the auditory-perceptual limitations imposed by CIs is likely to impact acquisition of these sounds: because spectral information is particularly distorted, children have limited access to the cues that differentiate these sounds.Twenty-eight children with CIs and a group of peers with normal hearing (NH) who were matched in terms of age, sex, and maternal education levels participated in this project. The experiment required children to repeat familiar words with initial /t/, /k/, /s/, or /ʃ/ following an auditory model and picture prompt. To create in-depth speech profiles and examine variability both within and across children, target consonants were elicited many times in front-vowel and back-vowel contexts. Patterns of accuracy and errors were analyzed based on transcriptions. Acoustic robustness of contrast was analyzed based on correct productions. Centroid frequencies were calculated from the release-burst spectra for /t/ and /k/ and the fricative noise spectra for /s/ and /ʃ/. Results showed that children with CIs demonstrated patterns not observed in children with NH. Findings provide evidence that for children with CIs, speech acquisition is not simply delayed due to a period of auditory deprivation prior to implantation. Idiosyncratic patterns in speech production are explained in-part by the limitations of CI’s speech-processing algorithms. The first chapter of this dissertation provides a general introduction. The second chapter includes a validation study for a measure to differentiate /t/ and /k/ in adults’ productions. The third chapter analyzes accuracy, errors, and spectral features of /t/ and /k/ across groups of children with and without CIs. The fourth chapter analyzes /s/ and /ʃ/ across groups of children, as well as the spectral robustness of both the /t/-/k/ and the /s/-/ʃ/ contrasts across adults and children. The final chapter discusses future directions for research and clinical applications for speech-language pathologists.Item The Development of Syntactic Complexity and the Irregular Past Tense in Children Who Do and Do Not Stutter(2009) Bauman, Jessica; Ratner, Nan B; Hearing and Speech Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This study examined spontaneous language samples and standardized test data obtained from 31 pairs of children who stutter (CWS), ages 25-59 months, and age-matched children who do not stutter (CWNS). Developmental Sentence Scores (DSS; Lee, 1974) as well as the relationships among age, DSS, and other standardized test scores were compared for both groups. No substantial differences were found between groups in the syntactic complexity of spontaneous language; however, the two groups show different relationships between age and DSS and between test scores and DSS. Additionally, observed differences between CWS and CWNS in patterns of past-tense errors and usage are discussed in light of a recent theoretical model of language performance in populations with suspected basal ganglia involvement (Ullman, 2004).Item Speech Recognition in Noise and Intonation Recognition in Primary-School-Aged Children, and Preliminary Results in Children with Cochlear Implants(2008-05-13) Wawroski, Lauren Ruth; Chatterjee, Monita; Hearing and Speech Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Fundamental frequency (F0), or voice pitch, is an important acoustic cue for speech intonation and is perceived most accurately through the fine spectral resolution of the normal human auditory system. However, relatively little is known about how young children process F0-based speech intonation cues. The fine spectral resolution required for F0 information has also been shown to be beneficial for listening in noise, a skill that normally-hearing children are required to use on a daily basis. While it is known that hearing-impaired adults with cochlear implants are at a disadvantage for intonation recognition and listening in noise following loss of fine spectral structure cues, relatively little is known about how young children with unilateral cochlear implants perform in these situations. The goal of the current study was to quantify how a group of twenty normally-hearing children (6-8 years of age) perform in a listening-in-noise task and in a speech intonation recognition task. These skills were also measured in a small group of 5 children of similar age with unilateral cochlear implants (all implanted prior to the age of five). The cochlear implant participants in this study presumably had reduced spectral information, and it was hypothesized that this would be manifested as performance differences between groups. In the listening-in-noise task, sentence recognition was measured in the presence of a single-talker masker at different signal-to-noise ratios. Results indicated that the participants with cochlear implants achieved significantly lower scores than the normally-hearing participants. In the intonation recognition task, listeners heard re-synthesized versions of a single bisyllabic word ("popcorn") with systematically varying F0 contours, and indicated whether the speaker was "asking" or "telling" (i.e., question-like or statement-like). Both groups of children were able to use the F0 cue to perform the task, and no significant differences between the groups were observed. Although limited in scope, the results suggest that children who receive their cochlear implant before the age of five have significantly more difficulty understanding speech in noise than their normally-hearing peers. However, the two populations appear to be equally able to use F0 cues to determine speech intonation patterns.