Search results for "speech recognition"
showing 10 items of 357 documents
2021
In vowel discrimination, commonly found discrimination patterns are directional asymmetries where discrimination is faster (or easier) if differing vowels are presented in a certain sequence compared to the reversed sequence. Different models of speech sound processing try to account for these asymmetries based on either phonetic or phonological properties. In this study, we tested and compared two of those often-discussed models, namely the Featurally Underspecified Lexicon (FUL) model (Lahiri and Reetz, 2002) and the Natural Referent Vowel (NRV) framework (Polka and Bohn, 2011). While most studies presented isolated vowels, we investigated a large stimulus set of German vowels in a more n…
Does "whole-word shape" play a role in visual word recognition?
2002
To analyze the impact of outline shape on visual word recognition, the visual pattern of the stimuli can be distorted by size alternation. Contrary to the predictions of models that rely on outline shape (Allen, Wallace, & Weber, 1995), the effect of size alternationwas greater for low-frequency words than for high-frequency words in a lexical decision task (Experiment 1). In Experiment 2, the effect of case type (lowercase vs. UPPERCASE) occurred for low-frequency words, but not for high-frequency words. The effect of neighborhood size was remarkably similar in the two experiments. The results can be readily explained in the framework of a resonance model (Grossberg & Stone, 1986), in whic…
A role for backward transitional probabilities in word segmentation?
2008
A number of studies have shown that people exploit transitional probabilities between successive syllables to segment a stream of artificial continuous speech into words. It is often assumed that what is actually exploited are the forward transitional probabilities (given XY, the probability that X will be followed by Y ), even though the backward transitional probabilities (the probability that Y has been preceded by X) were equally informative about word structure in the languages involved in those studies. In two experiments, we showed that participants were able to learn the words from an artificial speech stream when the only available cues were the backward transitional probabilities.…
Editorial: Breakthrough BCI Applications in Medicine
2020
Beyond the word and image: III. Neurodynamic properties of the semantic network
2019
AbstractUnderstanding the neural process underlying the comprehension of visual images and sentences remains a major open challenge in cognitive neuroscience. We previously demonstrated with fMRI and DTI that comprehension of visual images and sentences describing human activities recruits a common semantic system. The current research tests the hypothesis that this common semantic system will display similar neural dynamics during processing in these two modalities. To investigate these neural dynamics we recorded EEG from naïve subjects as they saw simple narratives made up of a first visual image depicting a human event, followed by a second that was either a sequentially coherent narrat…
Epilepsy stages diagnosis by Gabor atom density according to their aspect ratio
2008
During epilepsy seizure Electrocorticogram (ECoG) may change dramatically from a nearly chaotic signal (basal state) into a highly synchronized signal during a seizure, characterized by high amplitude and low frequency, and suddenly go back to the basal sate, making hard to identify them from time series. The epileptic seizure shows some stages as it is evolving, the here studied are: basal, preictal, ictal and posictal. As most of the bioelectrical signal, ECoG is a highly non periodical signal, so the most suitable techniques to analyze them are the Time-Frequency algorithms (T-F), allowing to follow up its frequency evolution through the seizure. Each seizure stage has a set of frequency…
Bioelectric model of atrial fibrillation: Applicability of blind source separation techniques for atrial activity estimation in atrial fibrillation e…
2003
In this contribution, we present the theoretical justification that give support to the suitability of blind signal separation (BSS) techniques for the estimation of the atrial activity (AA) present in ECGs of persistent atrial fibrillation (AF). The application of BSS methods to this problem needs the fulfillment of several conditions regarding AA, ventricular activity (VA) and the fashion in which both activities arise on the body surface, that will be justified along the paper. To empirically validate the model, an ICA method is applied to 10 real 12-lead recordings of AF. The identification of AA is put forward based on kurtosis and spectral analysis. The kurtosis value of the estimated…
Information-theoretic assessment of cardiovascular-brain networks during sleep
2015
This study was aimed at detecting the structure of the physiological network underlying the regulation of the cardiovascular and brain systems during normal sleep. To this end, we measured from the polysomnographic recordings of 10 healthy subjects the normalized spectral power of heart rate variability in the high frequency band (HF) and the EEG power in the δ, θ, α, σ, and β bands. Then, the causal statistical dependencies within and between these six time series were assessed in terms of internal information (conditional self entropy, CSE) and information transfer (transfer entropy, TE) computed via a linear method exploiting multiple regression models and a nonlinear method combining ne…
Truncation effects on muscular fatigue indexes based on M waves analysis
2012
International audience; In this paper, we investigate muscular fatigue. We propose a new fatigue index based on the continuous wavelet transform (CWT) and compare it with the standard fatigue indexes from literature. Fatigue indexes are all based on the electrical activity of muscles (electromyogram) acquired during an electrically stimulated contraction (ES). The stimulator and electromyogram system, which were presented in a previous work, allows real-time analysis. The extracted fatigue parameters are compared between each other and their sensitivity to noise is studied. The effect of truncation of M waves is then investigated, enlightening the robustness of the index obtained using CWT.
Multi axis representation and Euclidean distance of muscle fatigue indexes during evoked contractions
2014
International audience; In this article, we proposed a new representation of muscular fatigue during evoked muscle contractions based on fatigue indexes such as peak to peak amplitude, RMS of the M wave, mean and median frequency and fatigue index calculated from continuous wavelet transform (I CWT). These new representations of muscle fatigue using multi axis represented and Euclidean distance give better insights on changes in physiological characteristics during muscle fatigue. This technique provides a fatigue index using several muscle characteristics. The use of other kinds of fatigue characteristics as force could also be possible.