Browsing by Subject "Auditory processing"

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    An Electrophysiological Investigation of Linguistic Pitch Processing in Tonal-language-speaking Children with Autism
    (2018-09) Yu, Luodi
    Speech perception is a fundamental skill interfacing sound to meaning; however, systematic characterization of autism in relation to this issue is still lacking, presumably due to insufficient consideration of the language-specific nature of speech processing. Although nearly 70% of world languages are tonal, tonal language users have been significantly under-represented in autism research. An overview of the limited literature reveals that there is a trend of distinct patterns across different language users (i.e., tonal language vs. non-tonal language), indicating potentially disrupted neural specialization for linguistic structures in individuals with autism. This dissertation examined the rapid cortical processing of pitch patterns varying in linguistic status in native Chinese school-age children with autism and age-matched typically developing (TD) peers using electroencephalography (EEG). The auditory stimuli were nonsense speech and nonspeech sounds presented in passive listening conditions. In comparison with the TD group, the autism group displayed neural timing issues at various levels of information processing as indicated by neural response latency. Moreover, the autism group displayed not only hyposensitivity for native vs. nonnative (or prototypical vs. non-prototypical) difference in the early information processing stage but also hypersensitivity in the later processing stage accompanied by diffusive scalp distribution with a rightward dominance. The results collectively support the idea of disrupted neural specialization for linguistic structures in autism. The findings underscore the proposition that autism is bound with auditory and phonological atypicalities in addition to the syndromic social and communication deficits, which have important implications for requiring language-specific considerations in autism research and clinical practice.
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    Information Processing in Complex Environments: Insights from Treefrog Communication
    (2021-12) Gupta, Saumya
    Many animals use sounds to perform critical biological functions, such as choosing a mate or evading a predator, in environments where multiple sound sources are simultaneously active. Discerning a sound of interest in such complex acoustic environments, however, is not a trivial task. It requires animals to perceptually organize mixtures of auditory input into meaningful information about their external environment. In this dissertation research, my broad aim was to understand how animals parse their complex acoustic environments to perform acoustically guided behaviors. Using Cope’s gray treefrogs (Hyla chrysoscelis) as a model system, I investigated how animals accomplish the different perceptual tasks that are required for recognizing and responding to a signal of interest in noisy social environments. I discovered some of the processes that act together to extract information and facilitate signal recognition. Specifically, I found a perceptual mechanism that allows animals to perceive the different vocal signals in their environment as distinct sounds. I also found specific neural adaptations that allow them to extract and recognize biologically meaningful information from their vocal signals. Additionally, my research reveals that despite the evolution of these perceptual and sensorineural mechanisms, background sounds present in the social environment can interfere with the information processing capacity of animals, and thus, can critically constrain their ability to perform important biological functions. This research opens up an exciting and unknown question of how animals are evolutionarily adapted to overcome the limitations in information processing to perform acoustically guided behaviors.