Tone processing and the acquisition of tone in Mandarin- and English-speaking typically developing children and children with Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is characterised by pervasive social difficulties, which partly manifest themselves in inappropriate pragmatics. It has also been hypothesised that individuals with ASD, or at least those on the lower-functioning end of the autism spectrum, may also have atypical pitch and musical perception. This thesis investigates pitch perception in autism in a domain where pitch is directly represented in the grammar: tones. Tone perception was investigated in a series of four experiments with high-functioning English and Mandarin ASD participants with and without language problems and their corresponding TD groups. The first experiment involved a tone comprehension task (only for the Mandarin participants) using picture-matching. The second experiment involved a psychoacoustic tone discrimination task using the Mandarin Tone 1-4 continuum. The third experiment was a categorical perception task involving two tasks: a naming task and a two-step identification task. The results of the experiments indicated subtle but persistent issues with the grammatical representation of tones for Mandarin ASD speakers, especially for those with language problems. Although ASD participants’ tone comprehension and tone discrimination abilities are essentially in line with their typical peers, they have different error patterns in comprehension of Tone 2-3 distinctions and they treat nonce word stimuli more like pure tone stimuli in identification, suggesting a weaker representation of abstract tones. In addition, the categorical perception task revealed that although the performance of Mandarin ASD participants in the naming task was not distinguishable from their typically developing peers, the two-step identification task revealed a less strongly categorical perception of the Tone 1-4 continuum. In addition, the performance of the ASD SLP groups was also overall worse. These results altogether constitute a significant discovery of a grammatical impairment of people living with ASD. This population might have prosodic impairments relating their pitch perception, and their ability to categorise pitch contours in a grammatical fashion, in addition to their pragmatic difficulties

An exploratory study of imagining sounds and “hearing” music in autism

Individuals with autism spectrum disorder (ASD) reportedly possess preserved or superior music-processing skills compared to their typically developing counterparts. We examined auditory imagery and earworms (tunes that get “stuck” in the head) in adults with ASD and controls. Both groups completed a short earworm questionnaire together with the Bucknell Auditory Imagery Scale. Results showed poorer auditory imagery in the ASD group for all types of auditory imagery. However, the ASD group did not report fewer earworms than matched controls. These data suggest a possible basis in poor auditory imagery for poor prosody in ASD, but also highlight a separability between auditory imagery and control of musical memories. The separability is present in the ASD group but not in typically developing individuals

Language Profiles Of Thai Children With Autism: Lexical, Grammatical, And Pragmatic Factors

This dissertation is a linguistically-motivated investigation into different areas of language in children with autism spectrum disorders (ASD), compared to typically developing (TD) children. Fine distinctions between linguistic units were used in designing tasks on language production and comprehension in seven experiments. The focus of each chapter of this dissertation was on three main hypotheses respectively, namely (1) the Abstract Representation Difficulty Hypothesis that children with ASD (perhaps limited to the subgroup with co-morbid language impairments) have difficulties activating abstract lexical representations as effectively as TD children, due to their hyperattention to phonetic details of speech, (2) the Pragmatic over Grammatical Deficit Hypothesis that pragmatics is particularly difficult for all the ASD children, while morphological and semantic aspects of language are relatively intact, and (3) the Cognitive Factor Hypothesis that cognitive factors such as nonverbal intelligence quotient (NVIQ) and nonverbal working memory play a greater role in the ASD than the TD performance on linguistic tasks. Chapter 2 investigates the morpho-phonological and semantic aspects of the lexical processing of Thai compound and simplex words. Results suggest that morphological facilitation effects can be obtained independently of phonological and semantic relatedness in the processing of Thai compounds. While children with ASD with lower task performance display hyper-attention to the acoustic differences between primes and targets, children with ASD in the higher performance group have enhanced morphological effects, compared to their TD peers, and the effects appear to be independent of the presence of phonological effects and enhanced semantic effects. The lack of phonological effects in the first set of experiments was explored further in the later experiments. Children with ASD were found to be slower in processing natural-sounding surface phonological forms, suggesting that a deeper processing of neutralized forms than full forms. The similar performance on the next task with the integration of visual information suggests that the slower processing may result from their slower lexical semantic processing. The Abstract Representation Difficulty Hypothesis, thus, holds for a subgroup of children with ASD, while other children with ASD display intact phonological representation, enhanced morphological processing compared to TD controls, and intact but slower lexical processing. Chapter 3 explores the Pragmatic over Grammatical Deficits Hypothesis. Using fine distinctions within the personal reference terms, consistently replicated results suggest that while grammatical person phi-features are intact in children with ASD\u27s representation of pronouns, these children are less sensitive to deictic information in their interpretation of pronouns and tend to avoid using the first-person pronoun, with high deictic level, when they have freedom to choose personal names to refer to themselves. Children with ASD also performed more poorly on the comprehension of unmarked pronouns which requires implicated presupposition, suggesting that even with minimal comparisons among the pronouns, lexically-encoded core grammatical features and pragmatic ones are distinguished in children\u27s language processing. Chapter 3 also adds to the literature on lexical presuppositions, scalar implicature, and implicated presuppositions that not only adolescents, but also children with ASD are age-appropriate in deriving scalar implicatures and that not all kinds of pragmatic inferences are equally challenging for children with ASD. The most indicative difference between the children with ASD and the TD group lies in the children with ASD\u27s heavier reliance on literal, logical meaning when other semantically- and pragmatically-inferred meanings are violated. Chapter 4 partly contributes to the Cognitive Factor Hypothesis, suggesting a possibility that cognitive factors, as opposed to developmental factors, correlates more with children with ASD\u27s performance on linguistic tasks. Additionally, children in both groups displayed correlations in their performance across all of the experiment in the dissertation. Individual language profiles were compiled with the results from the previous chapters. Two subgroups of children with ASD were identified through k-means cluster analysis. The children with ASD in Cluster 1 have globally better performance across experiments than children with ASD in Cluster 2, supporting that ASD children may be able to be classified into subgroups based on their performance on linguistic tasks alone. Even with globally better linguistic task performance, the children with ASD in Cluster 1 still appear to be less sensitive to social-deictic information, confirming that certain types of pragmatics are indeed more challenging than the others. In sum, this dissertation advances our understanding on morphological, semantic, and pragmatic abilities of children with autism through carefully-designed linguistically-motivated experiments

Lexical Context Effects on Speech Perception in Chinese People with Autistic Traits

One theory (weak central coherence) that accounts for a different perceptual-cognitive style in autism may suggest the possibility that individuals with autism are less likely to be affected by lexical knowledge on speech perception. This lexical context effects on speech perception has been evidenced by Ganong (1980) by using word-to-nonword identification test along a VOT dimension. This Ganong effect (which suggests that people tend to make their percept a real word) can be seen as one kind of central coherence. However, the boundary of the VOT contrast in Chinese is different from English, so the present study firstly explores the Ganong effect in Chinese and then adopts this effect in a neurotypical population of Chinese with different degrees of autistic traits in order to test the hypothesis. Seventeen graduate students of Chinese from Taiwan took part in the present experiment with the Autism-Spectrum Quotient (AQ) as their index of autistic traits and word-to-nonword identification task (die2-tie2 and tiao2-diao2). Other factors, such as auditory sensitivity and slower lexical access that may potentially influence reduced lexical context effects in autism are considered. The result indicated that Ganong effect was significant in Chinese as well and an inverse relationship between the identification shift (Ganong effect) and one of the subsections of AQ (‘attention todetail’) was significant. The AQ score or word-to-nonword identification task did not correlate with scores on tasks (that examined auditory sensitivity and slower lexical access). It suggested that those extraneous factors can be ruled out

Neural correlates of indicators of sound change in Cantonese: evidence from cortical and subcortical processes

Across time, languages undergo changes in phonetic, syntactic and semantic dimensions. Social, cognitive and cultural factors contribute to sound change, a phenomenon in which the phonetics of a language undergo changes over time. Individuals who misperceive and produce speech in a slightly divergent manner (called innovators) contribute to variability in the society, eventually leading to sound change. However, the cause of variability in these individuals is still unknown. In this study, we examined whether such misperceptions are represented in neural processes of the auditory system. We investigated behavioral, subcortical (via FFR), and cortical (via P300) manifestations of sound change processing in Cantonese, a Chinese language in which several lexical tones are merging. Across the merging categories, we observed a similar gradation of speech perception abilities in both behavior and the brain (subcortical and cortical processes). Further, we also found that behavioral evidence of tone merging correlated with subjects’ encoding at the subcortical and cortical levels. These findings indicate that tone-merger categories, that are indicators of sound change in Cantonese, are represented neurophysiologically with high fidelity. Using our results, we speculate that innovators encode speech in a slightly deviant neurophysiological manner, and thus produce speech divergently that eventually spreads across the community and contributes to sound change

A Sound Approach to Language Matters: In Honor of Ocke-Schwen Bohn

The contributions in this Festschrift were written by Ocke’s current and former PhD-students, colleagues and research collaborators. The Festschrift is divided into six sections, moving from the smallest building blocks of language, through gradually expanding objects of linguistic inquiry to the highest levels of description - all of which have formed a part of Ocke’s career, in connection with his teaching and/or his academic productions: “Segments”, “Perception of Accent”, “Between Sounds and Graphemes”, “Prosody”, “Morphology and Syntax” and “Second Language Acquisition”. Each one of these illustrates a sound approach to language matters

Cortical auditory processing of informational masking effects by target-masker similarity and stimulus uncertainty

Purpose: Understanding speech in a background of other people talking is one of the most difficult listening challenges for hearing-impaired individuals, and even for those with normal hearing. Speech-on-speech masking, is known to contribute to increased perceptual difficulty over non-speech background noise because of informational masking provided over and above the energetic masking effect. While informational masking research has identified factors of similarity and uncertainty between target and masker that contribute to reduced behavioral performance in speech background noise, critical gaps in knowledge including the underlying neural-perceptual processes remain. By systematically manipulating aspects of similarity and uncertainty in the same auditory paradigm, the current study proposed to examine the time course and objectively quantify these informational masking effects at both early and late stages of auditory processing using auditory evoked potentials (AEPs) in a two-factor repeated measures paradigm. Method: Thirty participants were included in this cross sectional repeated measures design. Target-masker similarity between target and masker were manipulated by varying the linguistic/phonetic similarity (i.e. language) of the talkers in the noise maskers. Specifically, four levels representing hypothesized increasing levels of informational masking were implemented: (1) No masker (quiet), (2) Mandarin (linguistically and phonetically dissimilar), (3) Dutch (linguistically dissimilar, but phonetically similar), and (4) English (linguistically and phonetically similar). Stimulus uncertainty was manipulated by task complexity, specifically target-to-target interval (TTI) of an auditory paradigm. Participants had to discriminate between English word stimuli (/bæt/ and /pæt/) presented in an oddball paradigm in each masker condition at +3 dB SNR by pressing buttons to either the target or standard stimulus (pseudo-randomized between /bæt/ and /pæt/ for all participants). Responses were recorded simultaneously for P1-N1-P2 (standard waveform) and P3 (target waveform). This design allowed for simultaneous recording of multiple AEP peaks, including analysis of amplitude, area, and latency characteristics, as well as accuracy, reaction time, and d’ behavioral discrimination to button press responses. Finally, AEP measurers were compared to performance on a behavioral word recognition task (NU-6 25-word lists) in the proposed language maskers and at multiple signal-to-noise ratios (SNRs) to further explore if AEP components of amplitude/area and latency are correlated to behavioral outcomes across proposed maskers. Results: Several trends in AEP and behavioral outcomes were consistent with the hypothesized hierarchy of increasing linguistic/phonetic similarity from Mandarin to Dutch to English, but not all differences were significant. The most supported findings for this factor were that all babble maskers significantly affected outcomes compared to quiet, and that the native language English masker had the largest effect on outcomes in the AEP paradigm, including N1 amplitude, P3 amplitude and area, as well as decreased reaction time, accuracy, and d’ behavioral discrimination to target word responses. AEP outcomes for the Mandarin and Dutch maskers, however, were not significantly different across all measured components. Outcomes for AEP latencies for both N1 and P3 also supported an effect of stimulus uncertainty, consistent with a hypothesized increase in processing time related to increased task complexity when target stimulus timing was randomized. In addition, this effect was stronger, as evidenced by larger effect sizes, at the P3 level of auditory processing compared to the N1. An unanticipated result was the absence of the expected additive effect between linguistic/phonetic similarity and stimulus uncertainty. Finally, trends in behavioral word recognition performance were generally consistent with those observed for AEP component measures such that no differences between Dutch and Mandarin maskers were found, but the English masker yielded the lowest percent correct scores. Furthermore, correlations between behavioral word recognition and AEP component measures yielded some moderate correlations, but no common AEP components accounted for a majority of variance for behavioral word recognition. Conclusions: The results of this study add to our understanding of auditory perception in informational masking in four ways. First, observable effects of both similarity and uncertainty were evidenced at both early and late levels of auditory cortical processing. This supports the use of AEPs to better understand the informational masking deficit by providing a window into the auditory pathway. Second, stronger effects were found for P3 response, an active, top-down level of auditory processing providing some suggestion that while informational masking degradation happens at lower levels, higher level active auditory processing is more sensitive to informational masking deficits. Third, the lack of interaction of main effects leads us to a linear interpretation of the interaction of similarity and uncertainty with an equal effect across listening conditions. Fourth, even though there were few and only moderate correlations to behavioral word recognition, AEP and behavioral performance data followed the same trends as AEP measures across similarity. Through both auditory neural and behavioral testing, language maskers degraded AEPs and reduced word recognition, but particularly using a native-language masker. The behavioral and objective results from this study provide a foundation for further investigation of how the linguistic content of target and masker and task difficulty contribute to difficulty understanding speech in noise

Tailored perception: individuals’ speech and music perception strategies fit their perceptual abilities

Perception involves integration of multiple dimensions that often serve overlapping, redundant functions, e.g. pitch, duration, and amplitude in speech. Individuals tend to prioritize these dimensions differently (stable, individualized perceptual ‘strategies’) but the reason for this has remained unclear. Here we show that perceptual strategies relate to perceptual abilities. In a speech cue weighting experiment (trial N = 990), we first demonstrate that individuals with a severe deficit for pitch perception (congenital amusics; N=11) categorize linguistic stimuli similarly to controls (N=11) when the main distinguishing cue is duration, which they perceive normally. In contrast, in a prosodic task where pitch cues are the main distinguishing factor, we show that amusics place less importance on pitch and instead rely more on duration cues—even when pitch differences in the stimuli were large enough for amusics to discern. In a second experiment testing musical and prosodic phrase interpretation (N=16 amusics; 15 controls), we found that relying on duration allowed amusics to overcome their pitch deficits to perceive speech and music successfully. We conclude that auditory signals, because of their redundant nature, are robust to impairments for specific dimensions, and that optimal speech and music perception strategies depend not only on invariant acoustic dimensions (the physical signal), but on perceptual dimensions whose precision varies across individuals. Computational models of speech perception (indeed, all types of perception involving redundant cues e.g. vision and touch) should therefore aim to account for the precision of perceptual dimensions and characterize individuals as well as groups