Dissertation
Real-time lexical and semantic processing in school-age children with hearing aids and cochlear implants
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Summer 2020
DOI: 10.17077/etd.005556
Abstract
Children with any degree of hearing loss are at risk for delays in development of higher-level language skills that persist into mid-elementary school. To effectively comprehend speech, children need more than accurate word recognition—they must efficiently and rapidly use the speech input to access semantic representations of words in the moment. This dissertation investigates the possibility that children with hearing loss differ from children with normal hearing (NH) in these fundamental processes.
As a speech signal unfolds, all listeners must cope with temporary ambiguity. For example, as “sandal” is heard, “san-” could be the onset of numerous lexical candidates. Listeners immediately activate multiple candidates consistent with the speech input (e.g., “sandal,” “sandwich”). Activation spreads to semantic features of these candidates (e.g., “worn on foot,” “edible”), which facilitates activation of semantically related words (e.g., “sneaker,” “apple”). Once enough input is available, listeners suppress competitors. NH listeners require fast target word activation and competitor suppression to decode running speech efficiently. Prelingually deaf adolescents with cochlear implants (CIs) show a different pattern: they delay lexical access until substantial input arrives, resulting in decreased phonological competition (a “wait-and-see” approach). It is not clear how younger children with CIs, or any children with hearing aids (HAs), may differ in these strategies.
This dissertation asks if differences in these processes may underly some of the language difficulties of children with hearing loss. Such differences could arise both directly from their degraded in-the-moment auditory signal, and also indirectly as they acquired language via a degraded signal. In this study, 51 9- to 12-year-old children with CIs, HAs, and NH completed a visual world paradigm eye-tracking task. On each trial, subjects heard a word and selected the corresponding picture from a display of four. Eye movements were recorded throughout the task. Three types of competitors were examined: cohorts, in which the competing word overlapped phonologically with the target at onset; rhymes, in which the words overlapped at the end; and semantics, in which the words shared semantic features. A battery of additional assessments was administered to characterize audiological, linguistic, and cognitive abilities.
Analyses focused on the HA and NH groups due to limited sample size in the CI group. Relative to children with NH, children with HAs were slower to look to the target, looked less to the cohort competitor, and looked more to the rhyme competitor. This is consistent with a wait-and-see approach to spoken word recognition. Children with HAs were also slower to look to the semantically related item, and this delay was explained by speed of looking to the target and cohort. For both children with HAs and children with NH, a larger vocabulary was associated with faster looks to the target and cohort and overall higher looking to the semantically related item. Neither early auditory experience nor aided audibility at the time of the VWP task was associated with looking behavior on the VWP task for the children with HAs.
The results suggest that school-age children with HAs adopt a wait-and-see approach when recognizing spoken words, even when audibility and word recognition accuracy are high. The findings suggest that children with HAs alter their dynamics of lexical access and phonological competition based on a lifetime of uncertainty in the auditory signal. The findings have implications for our theoretical understanding of how listeners cognitively adapt to uncertain input, and implications for clinical intervention to support spoken language outcomes for children with hearing loss.
Details
- Title: Subtitle
- Real-time lexical and semantic processing in school-age children with hearing aids and cochlear implants
- Creators
- Kelsey Elizabeth Klein
- Contributors
- Elizabeth Walker (Advisor)Bob McMurray (Advisor)Carolyn Brown (Committee Member)Kristi Hendrickson (Committee Member)Karla McGregor (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Speech and Hearing Science
- Date degree season
- Summer 2020
- DOI
- 10.17077/etd.005556
- Publisher
- University of Iowa
- Number of pages
- xii, 157 pages
- Copyright
- Copyright 2020 Kelsey Elizabeth Klein
- Language
- English
- Description illustrations
- color illustrations
- Description bibliographic
- Includes bibliographical references (pages 146-157).
- Public Abstract (ETD)
Children with any degree of hearing loss (HL) are at risk for deficits in spoken language comprehension through at least elementary school, even when these children use hearing aids or cochlear implants that were fit early in life. One explanation for these continued language difficulties is that children with HL may be slower, or less efficient, at processing speech as they hear it, relative to children with normal hearing (NH). In this study, I used an eye-tracking task to examine the real-time cognitive processes that school-age children with HL use to recognize spoken words. I also investigated the extent to which vocabulary, working memory, and hearing history are associated with specific aspects of these word recognition processes.
In this study, children with HL who used hearing aids were slower than the children with NH to recognize the words they heard, even though both groups of children were highly accurate at eventually recognizing the words. Relative to children with NH, children with hearing aids needed to hear more of the target word before they began to mentally guess what the target word was. Because of this delay, children with hearing aids were also slower to recognize the meaning of the word they were hearing. Larger vocabulary was associated with more efficient word recognition abilities. Findings from this study will help researchers and clinicians to better understand and address spoken language deficits in children with HL.
- Academic Unit
- Communication Sciences and Disorders; Center for Social Science Innovation
- Record Identifier
- 9983987997302771
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