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Modulation of neural responses to naturalistic speech production and perception
Get PDFSpeech production is under-studied compared to speech perception largely due to complications in data collection caused by articulation. In electroencephalography (EEG), these complications manifest as electromyographic activity (EMG) originating from the muscles that control articulation (Chen et al. 2019). This is unfortunate because EEG is well-suited for studying the rapid temporal changes in speech production. In addition, the few EEG studies of speech production are limited to the single-word level, which limits the generalizability of studies to how speech is used in everyday contexts.
In this thesis I present an EEG study of the differences between speech production and perception using sentence-level naturalistic stimuli. Participants overtly produced sentences from the MOCHA-TIMIT (Wrench 1999) corpus then listened to playback of themselves producing the sentences. Perception trials were then split into predictable and unpredictable trials. Predictable trials consisted of playback of the previously produced sentence, while unpredictable trials consisted of playback of a randomly selected previously produced sentence. In this thesis, two contrasts are compared: (1) overt production of sentences versus passive listening to sentences, and (2) passive listening to predictable sentences versus passive listening to unpredictable sentences. Canonical correlation analysis (CCA) was used to remove EMG artifact from the recorded EEG.
To demonstrate removal of EMG and preservation of neural responses in CCA-corrected EEG data, event-related potential (ERP) analysis was used on neural responses to perception stimuli, inter-trial click tones, and activity recorded from auxiliary facial EMG electrodes. These ERP analyses revealed a reduction in amplitude for production trials and facial EMG activity after CCA artifact correction and a preservation of early auditory responses in inter-trial click tones, suggesting that EMG was successfully removed while preserving neural responses. After validation of EMG removal, perception and production trials were compared using ERP analysis. Responses to produced sentences were found to have reduced amplitude when compared with perceived sentences, which is consistent with previous research on speaker-induced suppression. Differences in stimulus predictability during speech perception had an effect on response amplitude as well; however, this difference was weaker than the difference in amplitudes observed while comparing the differences between perception and production trials. Multivariate temporal receptive field modeling was used to examine phonological tuning in perception and production. Models demonstrated that speaker-induced suppression does not reflect a change in neural encoding of phonological features but instead a generalized reduction in response amplitude during speech production. Understanding the differences between speech perception and production in a naturalistic context has implications for developing brain-computer interfaces and understanding the neural basis of communication disorders such as apraxia of speech and stuttering. This thesis also serves as a proof-of-concept for studying sentence-level speech production using EEG by demonstrating an effective way of removing EMG artifact while preserving integrity of neural responses.Communication Sciences and Disorder
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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Neural speech tracking in quiet and noisy listening environments using naturalistic stimuli
Get PDFIn noisy situations, speech may be masked with conflicting acoustics, including background noise from the environment or other competing talkers. The process of listening to one stream of sounds while ignoring background noise is referred to as the “cocktail party problem,” but its physiological basis remains poorly understood. In this study, we used electroencephalography (EEG) to measure neural responses to a continuous, controlled clean speech stimulus versus speech in naturalistic noise in 17 participants with typical hearing. We employed linear encoding models to assess the degree of neural tracking to specific speech features. These models allow us to predict neural activity from EEG based on specific acoustic or linguistic features in the speech stimulus over time. The aims of this project were the following: 1) assess the fidelity of neural tracking of speech features using a highly uncontrolled and naturalistic stimulus containing speech-in-noise alongside a clean speech condition, 2) characterize neural responses to acoustic features such as the speech envelope and pitch, along with linguistic features such as phonological features in both speech-in-noise and speech alone stimuli, 3) utilize a cross-prediction analysis to predict the neural responses to a speech-in-noise condition from a clean speech condition, and vice versa. The first two analyses seek to understand which speech features drive brain responses measured from the scalp. The purpose of the third analysis is to understand whether the predictions from our encoding model are generalizable to different types of stimuli. Our results demonstrated that model performance was more robust for the phonological features compared to the acoustic envelope in clean speech conditions, but combining acoustic and phonological features aided in listeners tracking speech in a noisy condition. Our ability to predict neural activity in response to speech sounds was higher when those sounds occurred without background noise. Finally, we predicted responses to the clean speech stimuli based on responses to the noisy speech stimuli, and vice versa. These results have implications for identifying which speech features could be used to build a brain-machine interface or a cognitive hearing aid to identify and separate speech from noise.Communication Sciences and Disorder
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The neural representation of simultaneous speech and music
Get PDFResearch on neural processing of speech in the presence of other sounds has mostly been limited to studies of the cocktail party problem, in which a target speech signal is superimposed on other speech. The processing of speech in combination with other types of sound, meanwhile, has received little research and is poorly understood. In the current study, electroencephalography (EEG) was used to measure listeners’ neural responses to stimuli consisting of overlapping segments of speech and different musical instruments. Presented here is a preliminary analysis of these data that indicates differential neural representation of component sounds in these mixtures. Possible explanations for this result are discussed, as well as potential future analyses of the data.Communication Sciences and Disorder
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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