Levels Of Speech Processing Research Articles

Multidisciplinary Cognitive Function Assessment of Good versus Poor Performance in Children with Cochlear Implants: An Observational Cross-Sectional Study.

Introduction Despite the developing technology of cochlear implants (CIs), implanted prelingual hearing-impaired children exhibit variable speech processing outcomes. When these children match in personal and implant-related criteria, the CI outcome variability could be related to higher-order cognitive impairment. Objectives To evaluate different domains of cognitive function in good versus poor CI performers using a multidisciplinary approach and to find the relationship between these functions and different levels of speech processing. Methods This observational, cross-sectional study used the word recognition score (WRS) test to categorize 40 children with CIs into 20 good (WRS/65%) and 20 poor performers (WRS < 65%). All participants were examined for speech processing at different levels (auditory processing and spoken language) and cognitive functioning using (1) verbal tests (verbal component of Stanford-Binet intelligence [SBIS], auditory memory, auditory vigilance, and P300); and (2) performance tasks (performance components of SBIS, and trail making test). Results The outcomes of speech processing at different functional levels and both domains of cognitive function were analyzed and correlated. Speech processing was impaired significantly in poor CI performers. This group also showed a significant cognitive function deficit, in which the verbal abilities were more affected (in 93.5%) than in the good performers (in 69.5%). Moreover, cognitive function revealed a significant correlation and predictive effect on the CI speech outcomes. Conclusion Cognitive function impairment represented an important factor that underlies the variable speech proficiency in cochlear-implanted children. A multidisciplinary evaluation of cognitive function would provide a comprehensive overview to improve training strategies.

One-to-One or One Too Many? Linking Sound-to-Letter Mappings to Speech Sound Perception and Production in Early Readers.

Effects related to literacy acquisition have been observed at different levels of speech processing. This study investigated the link between orthographic knowledge and children's perception and production of specific speech sounds. Sixty Spanish-speaking second graders, differing in their phonological decoding skills, completed a speech perception and a production task. In the perception task, a behavioral adaptation of the oddball paradigm was used. Children had to detect orthographically consistent /t/, which has a unique orthographic representation (〈t〉), and inconsistent /k/, which maps onto three different graphemes (〈c〉, 〈qu〉, and 〈k〉), both appearing infrequently within a repetitive auditory sequence. In the production task, children produced these same sounds in meaningless syllables. Perception results show that all children were faster at detecting consistent than inconsistent sounds regardless of their decoding skills. In the production task, however, the same facilitation for consistent sounds was linked to better decoding skills. These findings demonstrate differences in speech sound processing related to literacy acquisition. Literacy acquisition may therefore affect already-formed speech sound representations. Crucially, the strength of this link in production is modulated by individual decoding skills.

Masking of the mouth area impairs reconstruction of acoustic speech features and higher-level segmentational features in the presence of a distractor speaker

Multisensory integration enables stimulus representation even when the sensory input in a single modality is weak. In the context of speech, when confronted with a degraded acoustic signal, congruent visual inputs promote comprehension. When this input is masked, speech comprehension consequently becomes more difficult. But it still remains inconclusive which levels of speech processing are affected under which circumstances by occluding the mouth area. To answer this question, we conducted an audiovisual (AV) multi-speaker experiment using naturalistic speech. In half of the trials, the target speaker wore a (surgical) face mask, while we measured the brain activity of normal hearing participants via magnetoencephalography (MEG). We additionally added a distractor speaker in half of the trials in order to create an ecologically difficult listening situation. A decoding model on the clear AV speech was trained and used to reconstruct crucial speech features in each condition. We found significant main effects of face masks on the reconstruction of acoustic features, such as the speech envelope and spectral speech features (i.e. pitch and formant frequencies), while reconstruction of higher level features of speech segmentation (phoneme and word onsets) were especially impaired through masks in difficult listening situations. As we used surgical face masks in our study, which only show mild effects on speech acoustics, we interpret our findings as the result of the missing visual input. Our findings extend previous behavioural results, by demonstrating the complex contextual effects of occluding relevant visual information on speech processing.

Introduction to the Special Issue on Biosignal-Based Spoken Communication

The papers in this special section focus on biosignal-based spoken communication. Speech production is a complex process resulting from human activities initiated in the brain, eventually leading to muscle activities that produce respiratory, laryngeal, and articulatory gestures which finally create acoustic signals. Traditional speech processing systems capture and interpret the acoustic signal of speech. However, speech is not only limited to acoustics - speech-related activities can be measured at each level of speech processing, including the central and peripheral nervous systems, muscular action potentials, and speech kinematics. Their measurement, obtained through recordings from variety of sensor technologies, results in speech-related that have been studied for decades to better understand the underlying mechanisms of human speech processing. However, there is more: speech-related biosignals have the potential to overcome limitations of traditional acoustic-based systems for spoken communication. Biosignals can be captured before the airborne acoustic signal and are thus less prone to environmental noise. Also, they do not rely on the production of audible speech - both features open up newtracks for Biosignalbased Spoken Communication. Examples of these tracks include Brain-Computer Interfaces allowing for communication by directly decoding cortical brain activity into speech representations, and Silent-Speech Interfaces, which offer a way to communicate privately without disturbing bystanders and to restore spoken communication for people who lost their voice due to severe speech impairments. Furthermore, biosignals could provide valuable articulatory biofeedback to speakers about their own voice production for increasing articulatory awareness in speech therapy or language learning.

A phenomenon called Mondegreen

The term Mondegreens describes misperceptions as defined by "slips of the ear", denoting that an utterance is perceived differently to what has actually been said. The analysis of these misperceptions permits a deeper insight into speech processing in the human brain. A selective literature research in PubMed has been carried out for this systematic review. Altogether, 24 publications were found addressing the issue of auditory misperceptions. The analysis of Mondegreens enables a characterization of the different levels of speech processing as well as the processing steps involved. The hard of hearing in particular suffer from misperceptions. Therefore, it should be considered whether listening programs could be helpful in combination with hearing aids.

The phonemic restoration effect reveals pre-N400 effect of supportive sentence context in speech perception

The phonemic restoration effect refers to the tendency for people to hallucinate a phoneme replaced by a non-speech sound (e.g., a tone) in a word. This illusion can be influenced by preceding sentential context providing information about the likelihood of the missing phoneme. The saliency of the illusion suggests that supportive context can affect relatively low (phonemic or lower) levels of speech processing. Indeed, a previous event-related brain potential (ERP) investigation of the phonemic restoration effect found that the processing of coughs replacing high versus low probability phonemes in sentential words differed from each other as early as the auditory N1 (120–180 ms post-stimulus); this result, however, was confounded by physical differences between the high and low probability speech stimuli, thus it could have been caused by factors such as habituation and not by supportive context. We conducted a similar ERP experiment avoiding this confound by using the same auditory stimuli preceded by text that made critical phonemes more or less probable. We too found the robust N400 effect of phoneme/word probability, but did not observe the early N1 effect. We did however observe a left posterior effect of phoneme/word probability around 192–224 ms—clear evidence of a relatively early effect of supportive sentence context in speech comprehension distinct from the N400.

Teaching and Learning Guide for: Speaking and Hearing Clearly: Talker and Listener Factors in Speaking Style Changes

Teaching and Learning Guide for: Speaking and Hearing Clearly: Talker and Listener Factors in Speaking Style Changes

Bringing neuroimaging tools closer to diagnostic use in the severely injured brain

In a vanguard study reported in this issue of Brain , Coleman et al. (page 2494) used hierarchically organized passive language tasks and functional magnetic resonance imaging (fMRI) to study 14 patients with severe brain injuries. Functional levels of the study subjects ranged across a spectrum from vegetative state to minimally conscious state, and severe disability following emergence from the minimally conscious state. The investigators assessed three levels of speech processing beginning with comparisons of auditory stimuli to a silent baseline, followed by comparisons of intelligible speech versus unintelligible noise, and finally advancing to high-level semantic contrasts using English sentences containing words with either high or low ambiguity of interpretation. Notably, their findings revealed evidence of preserved higher level language processing among a subset of three patients meeting the criteria for vegetative state. Taken together with an earlier single-subject study of one of the vegetative state patients (Owen et al. , 2006), the results support further developing these and other neuroimaging tools to aid the difficult diagnostic assessments of patients with severe brain injuries (Laureys et al. , 2004; Schiff, 2006). Owen et al. (2006) earlier demonstrated at least minimally conscious state level function in one of the three vegetative state patients using another novel imaging technique that is operationally exchangeable with behavioural evidence of command following as judged clinically at the bedside. The patient demonstrated the ability to follow complex commands. Based on these earlier studies, it could be strongly argued that this vegetative state patient in fact reflects a novel category of ‘non-behavioural’ minimally conscious state (Fins and Schiff, 2006). This distinction may ultimately be of considerable importance as prospective studies …

Do vegetative patients retain aspects of language comprehension? Evidence from fMRI

A diagnosis of vegetative state is made if a patient demonstrates no evidence of awareness of self or environment, no evidence of sustained, reproducible, purposeful or voluntary behavioural response to sensory stimuli and critically no evidence of language comprehension. For those patients who retain peripheral motor function, rigorous behavioural assessment is usually able to determine retained function. However, some patients do not retain the ability to respond overtly to command and it is becoming increasingly accepted that assessment of these patients should include techniques, which do not rely on any 'motor action' on the part of the patient. Here, we apply a hierarchical functional magnetic resonance imaging (fMRI) auditory processing paradigm to determine the extent of retained language processing in a group of 14 aetiologically heterogeneous patients who met the diagnostic criteria for either the vegetative state (n = 7), the minimally conscious state (n = 5), or who were in a severely disabled condition having emerged from a minimally conscious state (n = 2). Three different levels of speech processing were assessed: (i) Low-level auditory responses were measured using a contrast between a set of auditory stimuli and a silence baseline; (ii) mid-level speech perception processing abilities were assessed by comparing intelligible speech to unintelligible noise stimuli and (iii) high-level semantic aspects of speech processing were assessed by comparing sentences that were made difficult to understand by the presence of words that were semantically ambiguous compared to matched low-ambiguity sentences. As expected the two severely disabled, but conscious patients showed preserved speech processing at all three levels. However, contrary to the diagnostic criteria defining the vegetative state, three patients (1 traumatic, 2 non-traumatic aetiology) demonstrated some evidence of preserved speech processing. The remaining four patients (1 traumatic, 3 non-traumatic aetiology) with a diagnosis of vegetative state showed no significant activation in response to sound compared with silence. These results provide further evidence that a subset of patients fulfilling the behavioural criteria for the vegetative state retain islands of preserved cognitive function.

De E-Wiz à C-Clone. Recueil, modélisation et synthèse d'expressions authentiques

Different levels of affects are expressed in different levels of speech processing: expressions of emotions linked to an involuntarily triggered control, expressions of the speaker's attitudes and intentions and meta-linguistic expressive strategies. C-Clone is presented as an interactive cognitive architecture of the expressive communication. Authentic but controlled expressive corpora have been collected using a Wizard of Oz experimental platform (E-Wiz) The acoustic as well as video and some physiological signals were recorded synchronously. An auto-annotated subset of emotional expressions made possible the validation of the modeling of affective prosody into gradient contours. Moreover perceptive experiments show that no prosodic dimension is specific of an emotional value.

Identification of lexical–phonological networks in the superior temporal sulcus using functional magnetic resonance imaging

General agreement exists that dorsal aspects of the temporal lobe support the perception of speech but there is less agreement regarding the mapping between levels of speech processing and neural regions within the dorsal temporal lobe. The present experiment sought to identify temporal lobe regions that support one such level, namely, lexical-phonological representation/processing. To do this, we manipulated phonological neighborhood density, a variable that affects processing within lexical-phonological networks. In a functional magnetic resonance imaging experiment, 10 participants listened to blocks of either high-density or low-density words. High-density words produced significantly more activation in the posterior half of the superior temporal sulcus bilaterally, suggesting that these regions are involved in lexical-phonological processing networks.

Perceptual adjustment to highly compressed speech: effects of talker and rate changes.

This study investigated the perceptual adjustments that occur when listeners recognize highly compressed speech. In Experiment 1, adjustment was examined as a function of the amount of exposure to compressed speech by use of 2 different speakers and compression rates. The results demonstrated that adjustment takes place over a number of sentences, depending on the compression rate. Lower compression rates required less experience before full adjustment occurred. In Experiment 2, the impact of an abrupt change in talker characteristics was investigated; in Experiment 3, the impact of an abrupt change in compression rate was studied. The results of these 2 experiments indicated that sudden changes in talker characteristics or compression rate had little impact on the adjustment process. The findings are discussed with respect to the level of speech processing at which such adjustment might occur.

Japanese quail categorize /d/ across allophonic variation

Studies using animal subjects provide a unique opportunity to assess the nature of processes for perceiving speech. Demonstrations that animals have the ability to categorize speech sounds in ways similar to humans, serve to undermine claims that some levels of speech processing either are specific to humans or carry substantial cognitive requirements. In our study, Japanese quail were taught to discriminate natural CV + /s/ syllables beginning with /d/ from those beginning with /b/ or /g/. The phoneme /d/ was chosen because of its well‐documented context‐conditioned variability. Birds received food reinforcement for pecking a lighted key during repeated presentation of /d/ syllables, but were required to refrain from pecking in order for the presentation of /b/ and /g/ syllables to be terminated. The quail were first trained to discriminate /dæs/, /das/, /dus/, and /dis/ from tokens with the same vowels following /b/ and /g/. After reaching asymptotic performance for the /æ/, /a/, /u/, and /i/ contexts, birds were tested on novel tokens with the vowels /ε/, /Λ/, /v/, and /ɪ/. They received no reinforcement for pecking to novel tokens. Quail pecked substantially more to novel /d/ tokens than to novel /b/ or /g/ tokens, suggesting that they treated the novel stimuli as similar to their non‐novel counterparts. Apparently, there exist significant acoustic/auditory commonalities among the class of /d/ allophones that may serve as the basis of category formation for both humans and animals. [Work supported by NICHD.]

文章内に挿入された信号音の知覚

The so called click method was applied at different levels of speech processing. In Exp. I significantly more clicks which were superimposed on sentences were mislocated toward syntactic boundaries, and this phenomenon was observed to occur immediately after the presentation of stimuli. In Exp. II subjects were required to respond (a) immediately after they heard the click sound, (b) after the whole sentence was presented, (c) 15sec after the presentation of the sentence. Preliminary knowledge of sentences was also controlled. The results demonstrated that (1) syntactic boundary effect was irrelevant to S-R interval or to preliminary knowledge of background sentences, (2) when S-R interval became longer, backward mislocation toward a prior segment of the sentence increased. Some explanations of mislocation mechanism were briefly discussed.