Diagnosis Of Developmental Dyslexia Research Articles

Clinical diagnostic practices for Chinese developmental dyslexia

Objective: To explore the optimization of the standardized assessment tool for clinical diagnosis of Chinese developmental dyslexia (DD). Methods: A cross-sectional study was conducted from May to December 2023, in which 130 primary school children in grades 1 to 3 with clinical signs of literacy lag and positive screening results on the screening scales were recruited from the outpatient clinic of Child Health Care Medical Division, Shanghai Children's Hospital, Shanghai Jiao Tong University School of Medicine. Chinese dyslexia screening behavior checklist for primary students (CDSBC) was used as the screening scales, and supplemented by dyslexia checklist for Chinese children. Referring to the standard procedure of the"expert advice on diagnosis and intervention of chinese developmental dyslexia", the developmental dyslexia scale for standard mandarin (DDSSM) was used to evaluate the children's literacy-related cognitive abilities and conduct the diagnostic assessment, and divided the children into learning backward group and the DD group. The t-test and χ2 test were used to compare the differences in the distribution of intelligence, literacy and attention deficit hyperactivity disorder between the two groups. Spearman's correlation was used to analyze the correlation between the scores for each cognitive ability in the DDSSM and the CDSBC. Results: Of the 130 children, 90 were male, aged (8.3±1.0) years; 40 were female, aged (8.1±0.9) years. A final diagnosis of DD was made in 59 cases, of which 41 were males. There was no statistically significant difference in operational intelligence quotient (101±15 vs.100±15, t=0.53, P>0.05) and statistically significant difference in literacy of DDSSM (32±5 vs.21±4, t=11.56, P<0.001) between the learning backward group and the DD group. Eighteen cases (25.4%) of the learning backward group were children with attention deficit subtype attention deficit hyperactivity disorder (ADHD-I), and 16 cases (27.1%) in DD group, the difference in incidence between the two groups was not statistically significant (χ2=0.05, P>0.05). There were correlations between the DDSSM (for oral vocabulary, morphological awareness and orthographic awareness) and the CDSBC total score (r=-0.42, -0.32, -0.35, all P<0.01), but the correlations for visuospatial perception and rapid automatized naming with CDSBC total score were not statistically significant (r=-0.09 and -0.20,both P>0.05). Conclusions: For literacy-related cognitive abilities, screening scales CDSBC are not sufficiently useful for assessment, so the introduction of standardized assessment tools DDSSM is an optimization of the clinical diagnosis of Chinese DD, which is crucial for achieving accurate diagnosis and intervention.

Effects of a developmental dyslexia remediation protocol based on the training of audio-phonological cognitive processes in dyslexic children with high intellectual potential: study protocol for a multiple-baseline single-case experimental design

BackgroundThe significant prevalence of children with high intellectual potential (HIP) in the school-age population and the high rate of comorbidity with learning disabilities such as dyslexia has increased the demand for speech and language therapy and made it more complex. However, the management of dyslexic patients with high intellectual potential (HIP-DD) is poorly referenced in the literature. A large majority of studies on HIP-DD children focus on the screening and diagnosis of developmental dyslexia, but only a few address remediation. Developmental dyslexia is a severe and persistent disorder that affects the acquisition of reading and implies the impairment of several underlying cognitive processes. These include deficits in Categorical Perception, Rapid Automatized Naming, and phonological awareness, particularly phonemic awareness. Some authors claim that HIP-DD children's underlying deficits mainly concern rapid automatized naming and phonological awareness. Thus, the purpose of this study is to present a remediation protocol for developmental dyslexia in HIP-DD children. This protocol proposes to compare the effects on reading skills of an intensive intervention targeting categorical perception, rapid automatized naming, and phonemic analysis versus standard speech therapy remediation in HIP-DD children.MethodsA multiple-baseline single-case experimental design (A1BCA2) will be proposed to 4 French HIP-DD patients for a period of 30 weeks. Intervention phases B and C correspond to categorical perception training and rapid automatized naming training. During phases B and C, each training session will be associated with phonemic analysis training and a reading and writing task. At inclusion, a speech and language, psychological, and neuropsychological assessment will be performed to define the four patients' profiles. Patients will be assigned to the different baseline lengths using a simple computerized randomization procedure. The duration of the phases will be counterbalanced. The study will be double blinded. A weekly measurement of phonological and reading skills will be performed for the full duration of the study.DiscussionThe purpose of this protocol is to observe the evolution of reading skills with each type of intervention. From this observation, hypotheses concerning the remediation of developmental dyslexia in HIP-DD children can be tested. The strengths and limitations of the study are discussed.Trial registrationClinicalTrials.gov, NCT04028310. Registered on July 18, 2019. Version identifier is no. ID RCB 2019-A01453-54, 19-HPNCL-02, 07/18/2019.

EEG Interchannel Causality to Identify Source/Sink Phase Connectivity Patterns in Developmental Dyslexia.

While the brain connectivity network can inform the understanding and diagnosis of developmental dyslexia, its cause-effect relationships have not yet enough been examined. Employing electroencephalography signals and band-limited white noise stimulus at 4.8 Hz (prosodic-syllabic frequency), we measure the phase Granger causalities among channels to identify differences between dyslexic learners and controls, thereby proposing a method to calculate directional connectivity. As causal relationships run in both directions, we explore three scenarios, namely channels' activity as sources, as sinks, and in total. Our proposed method can be used for both classification and exploratory analysis. In all scenarios, we find confirmation of the established right-lateralized Theta sampling network anomaly, in line with the assumption of the temporal sampling framework of oscillatory differences in the Theta and Gamma bands. Further, we show that this anomaly primarily occurs in the causal relationships of channels acting as sinks, where it is significantly more pronounced than when only total activity is observed. In the sink scenario, our classifier obtains 0.84 and 0.88 accuracy and 0.87 and 0.93 AUC for the Theta and Gamma bands, respectively.

Investigating the prevalence and comorbidity of attention deficit hyperactivity disorder and developmental dyslexia in learners in a South African practice

Background: Dyslexia and attention deficit hyperactivity disorder (ADHD) are marked comorbid neurodevelopmental disorders with an estimated bidirectional comorbidity of 25% – 40%. Previous international studies have identified strong hereditary and neurological overlap between these disorders, but the comorbidity of these developmental disorders in a South African practice has not yet been explored.Methods: This retrospective study aimed to investigate the co-existence of ADHD and the specific learning disorder (SLD) related to reading known as developmental dyslexia (DD). Additionally, the study sought to determine possible correlations between the overlapping diagnostic factors of the two developmental disorders. The study database consisted of 847 learners ranging from 8 to 18 years of age. Study data were obtained through a parent questionnaire regarding scholastic difficulties as well as prior ADHD diagnosis and/or treatment. A comprehensive psychometric assessment of DD was conducted on each participant in the first language of educational instruction, that is English or Afrikaans, to establish a direct dyslexia diagnosis as inclusion criterion.Results: Of the 847 participants analysed in this study, 38.6% presented with a co-existing diagnosis of both ADHD and DD. However, there was no evidence of statistically significant interdependency between overlapping diagnostic factors of these two disorders.Conclusions: The zero-correlations in the mentioned areas may indicate an overlap of shared symptoms rather than of distinctive diagnostic approaches.

Rhythm as an independent determinant of developmental dyslexia.

Temporal accounts of Developmental Dyslexia (DD) postulate that a timing impairment plays an important role in this learning disorder. However, DD has been associated with timing disorders as well as other motor and cognitive dysfunctions. It is still unclear whether nonverbal timing skills per se may be considered as independent determinants of DD. In this study, we investigated the independent contribution of predictive timing to DD above and beyond the motor and cognitive dysfunctions typically associated with this disorder. Twenty-one children with DD (aged 8-12, nine females) and 27 controls (14 females) were evaluated on perceptual timing, finger tapping, fine motor control, as well as attention and executive tasks. Participants were native French speakers from various socioeconomic backgrounds. The performance of children with DD was poorer than that of controls in most of the tasks. Predictors of DD, as identified by logistic regression modeling, were beat perception and precision in tapping to the beat, which are both predictive timing variables, children's tapping rate, and cognitive flexibility. These data support temporal accounts of DD in which predictive timing impairments partially explain the core phonological deficit, independent from general motor and cognitive functioning, making predictive timing a valuable tool for early diagnosis and remediation of DD. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Dyslexia Telerehabilitation during the COVID-19 Pandemic: Results of a Rhythm-Based Intervention for Reading.

The COVID-19 outbreak necessitated a reorganization of the rehabilitation practices for Learning Disorders (LDs). During the lockdown phase, telerehabilitation offered the possibility to continue training interventions while enabling social distancing. Given such an advantage of telerehabilitation methods for LDs, clinical research is still needed to test the effectiveness of diverse teletraining approaches by comparing their outcomes with those of face-to-face interventions. To compare the effectiveness of telerehabilitation vs. in-presence rehabilitation of dyslexia, a rhythm-based intervention for reading, called Rhythmic Reading Training (RRT), was tested in a small-scale clinical trial during the lockdown phase of the COVID-19 pandemic. Thirty children aged 8–13 with a diagnosis of developmental dyslexia were assigned to either a telerehabilitation or an in-presence rehabilitation setting and received RRT for 10 biweekly sessions of 45 min, supervised by a trained practitioner. The results showed that both telerehabilitation and in-presence rehabilitation were effective in improving reading and rapid automatized naming in children with dyslexia and that the effects were comparable between settings. Therefore, RRT was found to be effective in spite of the administration method (remote or in-presence). These results confirm the potential of telemedicine for the rehabilitation of LDs. Clinical Trial ID: NCT04995471.

A predictive model for chinese children with developmental dyslexia—Based on a genetic algorithm optimized back-propagation neural network

The identification or the diagnosis of developmental dyslexia has long been a difficult issue, and traditional logistic regression predictive models have some defects. This study established a genetic algorithm optimized back-propagation neural network model to predict whether Chinese children have dyslexia based on data from 399 children (187 children with dyslexia and 212 typically developing children, 3rd–6th graders, aged 7–13 years). The model achieved an overall prediction accuracy of approximately 94%. Moreover, reading accuracy was the strongest factor in predicting Chinese dyslexic children, and phonological awareness, the accuracy rate of pseudocharacters, morphological awareness, reading fluency, rapid digit naming, and the reaction times of noncharacters also made important contributions to the prediction. In summary, the model we established in this study had an excellent predictive capability regarding Chinese children with/without developmental dyslexia. Furthermore, the genetic algorithm optimized back-propagation neural network model that substantially improves the prediction accuracy of Chinese dyslexia, has the potential to direct more targeted prevention and treatment strategies, and lay the foundation for the artificial intelligence expert diagnosis system for Chinese dyslexia.

多言語環境児における発達性読み書き障害の評価と診断 : 日本語-英語バイリンガル症例のケースシリーズ研究

多言語環境児における発達性読み書き障害の評価と診断 : 日本語-英語バイリンガル症例のケースシリーズ研究

Sensory auditory interval perception errors in developmental dyslexia

Developmental dyslexia (DD) is a heritable condition associated with reading, visual and auditory deficits. Atypical processes involved in low-level sensory coding have been implicated. We tested the contribution made by auditory magnocellular function using a behavioural task which considered the temporal difference between pairs of identical sinewave tones. Adult undergraduates with an existing diagnosis of DD (n = 78) were compared with controls (n = 111) from the same population on error rates and response times at different interval durations. Error rates and response times increased in both groups with increasing task difficulty. However, on average the DD group made uniformly more errors and slower decisions than controls. Unsupervised learning of error patterns exposed a trait continuum associated with individual differences in response efficiency. Difficulty in using temporal information in DD arising from impaired sensory coding in the auditory thalamus is suggested. The results provide strong support for the idea that auditory processing difficulties in dyslexia, along with visual and sensorimotor deficits, have a common neurodevelopmental cause.

Dyslexia Diagnosis by EEG Temporal and Spectral Descriptors: An Anomaly Detection Approach.

Diagnosis of learning difficulties is a challenging goal. There are huge number of factors involved in the evaluation procedure that present high variance among the population with the same difficulty. Diagnosis is usually performed by scoring subjects according to results obtained in different neuropsychological (performance-based) tests specifically designed to this end. One of the most frequent disorders is developmental dyslexia (DD), a specific difficulty in the acquisition of reading skills not related to mental age or inadequate schooling. Its prevalence is estimated between 5% and 12% of the population. Traditional tests for DD diagnosis aim to measure different behavioral variables involved in the reading process. In this paper, we propose a diagnostic method not based on behavioral variables but on involuntary neurophysiological responses to different auditory stimuli. The experiments performed use electroencephalography (EEG) signals to analyze the temporal behavior and the spectral content of the signal acquired from each electrode to extract relevant (temporal and spectral) features. Moreover, the relationship of the features extracted among electrodes allows to infer a connectivity-like model showing brain areas that process auditory stimuli in a synchronized way. Then an anomaly detection system based on the reconstruction residuals of an autoencoder using these features has been proposed. Hence, classification is performed by the proposed system based on the differences in the resulting connectivity models that have demonstrated to be a useful tool for differential diagnosis of DD as well as a method to step towards gaining a better knowledge of the brain processes involved in DD. The results corroborate that nonspeech stimulus modulated at specific frequencies related to the sampling processes developed in the brain to capture rhymes, syllables and phonemes produces effects in specific frequency bands that differentiate between controls and DD subjects. The proposed method showed relatively high sensitivity above 0.6, and up to 0.9 in some of the experiments.

The processing of rhythmic structures in music and prosody by children with developmental dyslexia and developmental language disorder.

Rhythm perception seems to be crucial to language development. Many studies have shown that children with developmental dyslexia and developmental language disorder have difficulties in processing rhythmic structures. In this study, we investigated the relationships between prosody and musical processing in Italian children with typical and atypical development. The tasks aimed to reproduce linguistic prosodic structures through musical sequences, offering a direct comparison between the two domains without violating the specificities of each one. About 16 Typically Developing children, 16 children with a diagnosis of Developmental Dyslexia, and 16 with a diagnosis of developmental language disorder (age 10-13years) participated in the experimental study. Three tasks were administered: an association task between a sentence and its humming version, a stress discrimination task (between couples of sounds reproducing the intonation of Italian trisyllabic words), and an association task between trisyllabic nonwords with different stress position and three-notes musical sequences with different musical stress. Children with developmental language disorder perform significantly lower than Typically Developing children on the humming test. By contrast, children with developmental dyslexia are significantly slower than TD in associating nonwords with musical sequences. Accuracy and speed in the experimental tests correlate with metaphonological, language, and word reading scores. Theoretical and clinical implications are discussed within a multidimensional model of neurodevelopmental disorders including prosodic and rhythmic skills at word and sentence level.

Are children with developmental dyslexia all the same? A cluster analysis with more than 300 cases.

Reading is vital to every aspect of modern life, exacerbated by reliance of the internet, email, and social media on the written medium. Developmental dyslexia (DD) characterizes a disorder in which the core deficit involves reading. Traditionally, DD is thought to be associated with a phonological impairment. However, recent evidence has begun to suggest that the reading impairment in some individuals is provoked by a visual processing deficit. In this paper, we present WISC‐IV data from more than 300 Italian children with a diagnosis of DD to investigate the manifestation of phonological and visual subtypes. Our results indicate the existence of two clusters of children with DD. In one cluster, the deficit was more pronounced in the phonological component, while both clusters were impaired in visual processing. These data indicate that DD may be an umbrella term that encompasses different profiles. From a theoretical perspective, our results demonstrate that dyslexia cannot be explained in terms of an isolated phonological deficit alone; visual impairment plays a crucial role. Moreover, general rather than specific accounts of DD are discussed.

Inhibition and Updating, but Not Switching, Predict Developmental Dyslexia and Individual Variation in Reading Ability.

To elucidate the core executive function profile (strengths and weaknesses in inhibition, updating, and switching) associated with dyslexia, this study explored executive function in 27 children with dyslexia and 29 age matched controls using sensitive z-mean measures of each ability and controlled for individual differences in processing speed. This study found that developmental dyslexia is associated with inhibition and updating, but not switching impairments, at the error z-mean composite level, whilst controlling for processing speed. Inhibition and updating (but not switching) error composites predicted both dyslexia likelihood and reading ability across the full range of variation from typical to atypical. The predictive relationships were such that those with poorer performance on inhibition and updating measures were significantly more likely to have a diagnosis of developmental dyslexia and also demonstrate poorer reading ability. These findings suggest that inhibition and updating abilities are associated with developmental dyslexia and predict reading ability. Future studies should explore executive function training as an intervention for children with dyslexia as core executive functions appear to be modifiable with training and may transfer to improved reading ability.

Rapid Automatized Naming, Verbal Working Memory, and Rhythm Discrimination as Predictors of Reading in Italian Undergraduate Students with and without Dyslexia.

Whereas the clinical manifestations and the neuropsychological predictors of Developmental Dyslexia (DD) are already well documented in Italian-speaking children, empirical evidence on DD in Italian adults is in contrast rather scarce. The aim of the present study was to investigate the role of a subset of neuropsychological skills, which have been identified by previous literature to be related to reading, in the decoding abilities of a group of Italian undergraduates with and without DD. For this purpose, 39 university students aged between 19 and 27 years, 19 of whom with a diagnosis of DD, underwent an assessment battery including standardized reading tests, rapid automatized naming (RAN), verbal working memory, and rhythmic pattern discrimination tests. Cross-group differences confirmed significantly lower performances of undergraduates with DD in all measures but rhythm discrimination, compared to typical readers, thus showing a non-compensated neuropsychological profile. Regression analyses showed that, while reading speed was strongly and uniquely predicted by RAN speed, reading accuracy was concurrently predicted by RAN and rhythmic abilities. Finally, RAN speed emerged as a strong predictor of reading performance and risk of receiving a diagnosis of DD.

GRIN2B mediates susceptibility to intelligence quotient and cognitive impairments in developmental dyslexia.

Developmental dyslexia (DD) is a complex heritable condition associated with impairments in multiple neurocognitive domains. Substantial heritability has been reported for DD and related phenotypes, and candidate genes have been identified. Recently, a candidate gene for human cognitive processes, that is, GRIN2B, has been found to be associated significantly with working memory in a German DD sample. In this study, we explored the contribution of six GRIN2B markers to DD and key DD-related phenotypes by association analyses in a sample of Italian nuclear families. Moreover, we assessed potential gene-by-environment interactions on DD-related phenotypes. We carried out a family-based association study to determine whether the GRIN2B gene influences both DD as a categorical trait and its related cognitive traits in a large cohort of 466 Italian nuclear families ascertained through a proband affected by DD. Moreover, we tested the role of the selected GRIN2B markers and a set of commonly described environmental moderators using a test for G×E interaction in sib pair-based association analysis of quantitative traits in 178 Italian nuclear families. Evidence for a significant association was found with the categorical diagnosis of DD, performance intelligence quotient, phonemic elision, and auditory short-term memory. No significant gene-by-environment effects were found. Our results add further evidence in support of GRIN2B contributing toward DD and deficits in DD. More specifically, our data support the view that GRIN2B influences DD as a categorical trait and its related quantitative phenotypes, thus shedding further light on the etiologic basis and the phenotypic complexity of this disorder.

Tutoria em leitura e escrita baseado no modelo de RTI – resposta à intervenção em crianças com dislexia do desenvolvimento

Objetivo analisar e comparar o desempenho em tarefas de leitura e escrita em crianças com dislexia do desenvolvimento após tutoria baseado no modelo de resposta à intervenção. Métodos participaram deste estudo 15 crianças com o diagnóstico interdisciplinar de dislexia do desenvolvimento de 2º ao 6º ano do ensino fundamental da rede pública municipal da cidade de Marília-SP, com faixa etária de oito a 12 anos de idade, de ambos os sexos, sendo 75% do sexo masculino, divididos em Grupo I – grupo experimental (sete crianças que receberam intervenção) e Grupo II – grupo controle (oito crianças não receberam a intervenção, os mesmos foram pareados segundo sexo e faixa etária com o Grupo I). As crianças foram submetidas ao levantamento diagnóstico de Leitura e Escrita e ao programa de intervenção em tutoria baseado no Modelo de Resposta à Intervenção . Os resultados foram analisados estatisticamente por meio do teste de Wilcoxon e Teste de Kruskal-Wallis para verificar possíveis diferenças de desempenho nas tarefas entre os grupos estudados. Resultados os resultados revelaram diferença estatisticamente significante entre o Grupo I e o Grupo II, onde as crianças com dislexia do Grupo I apresentaram desempenho superior na tarefade leitura de palavras e leitura do livro I em relação às crianças do Grupo II. Conclusão grupo I apresentou avanços significantes comparados à Grupo II, que não recebeu intervenção de tutoria.

KIAA0319 and ROBO1: evidence on association with reading and pleiotropic effects on language and mathematics abilities in developmental dyslexia

Substantial heritability has been reported for developmental dyslexia (DD), and KIAA0319 and ROBO1 appear as more than plausible candidate susceptibility genes for this developmental disorder. Converging evidence indicates that developmental difficulties in oral language and mathematics can predate or co-occur with DD, and substantial genetic correlations have been found between these abilities and reading traits. In this study, we explored the role of eight single-nucleotide polymorphisms spanning within KIAA0319 and ROBO1 genes, and DD as a dichotomic trait, related neuropsychological phenotypes and comorbid language and mathematical (dis)abilities in a large cohort of 493 Italian nuclear families ascertained through a proband with a diagnosis of DD. Marker-trait association was analyzed by implementing a general test of family-based association for quantitative traits (that is, the Quantitative Transmission Disequilibrium Test, version 2.5.1). By providing evidence for significant association with mathematics skills, our data add further result in support of ROBO1 contributing to the deficits in DD and its correlated phenotypes. Taken together, our findings shed further light into the etiologic basis and the phenotypic complexity of this developmental disorder.

Functional characteristics of developmental dyslexia in left-hemispheric posterior brain regions predate reading onset

Individuals with developmental dyslexia (DD) show a disruption in posterior left-hemispheric neural networks during phonological processing. Additionally, compensatory mechanisms in children and adults with DD have been located within frontal brain areas. However, it remains unclear when and how differences in posterior left-hemispheric networks manifest and whether compensatory mechanisms have already started to develop in the prereading brain. Here we investigate functional networks during phonological processing in 36 prereading children with a familial risk for DD (n = 18, average age = 66.50 mo) compared with age and IQ-matched controls (n = 18; average age = 65.61 mo). Functional neuroimaging results reveal reduced activation in prereading children with a family-history of DD (FHD(+)), compared with those without (FHD(-)), in bilateral occipitotemporal and left temporoparietal brain regions. This finding corresponds to previously identified hypoactivations in left hemispheric posterior brain regions for school-aged children and adults with a diagnosis of DD. Furthermore, left occipitotemporal and temporoparietal brain activity correlates positively with prereading skills in both groups. Our results suggest that differences in neural correlates of phonological processing in individuals with DD are not a result of reading failure, but are present before literacy acquisition starts. Additionally, no hyperactivation in frontal brain regions was observed, suggesting that compensatory mechanisms for reading failure are not yet present. Future longitudinal studies are needed to determine whether the identified differences may serve as neural premarkers for the early identification of children at risk for DD.

Neuropsychological Treatment of Dyslexia: Does Type of Treatment Matter?

In this study, 123 children with a diagnosis of developmental dyslexia were assigned to different treatment groups, either variations of Bakker’s intervention program based on the balance model or a control, a specific reading training group. Thorough cognitive and neuropsychological assessment allowed determination of the subtype of dyslexia according to the balance model and the neuropsychological profile with respect to reading and spelling abilities, verbal memory, and phonemic awareness. Characteristics of hemisphere-specific stimulation were systematically manipulated in an effort to shed light on the bases and mechanisms of reading improvement. It was shown that the effects of treatment vary according to type of dyslexia and that the different intervention programs have differential effects on reading-related neuropsychological functions. Since opposite effects can be produced by the same type of treatment in different dyslexia subtypes, the results of the study suggest that accurate classification of subtype on the base of reading and reading-related variables is advantageous for an optimal planning of the therapy.

Usefulness of low redundancy speech tests with dyslexic children

AbstractObjectives: Developmental dyslexia in children can affect auditory and linguistic skills. Due to the impairment of hearing discrimination, attention, memory and perception, dyslexia causes the inability to process and interpret linguistic and verbal information effectively. Standard audiological examination is much less useful than low redundancy speech tests and electro-physiological examination, which are the only objective measures of central auditory processing. The aim of the study was to assess the usefulness of low redundancy speech tests and dichotic tests in the diagnosis of developmental dyslexia in children. Methods: Ten children aged 7–15 years were tested by a dichotic numeral test, a dichotic verbal minimal-pair test, and a Calearo test. Results: The experiments demonstrated that the dyslectic group achieved worse results in the above tests compared to the control group. This suggests information exchange disorders between the hemispheres, a lack of synchronization of acoustic percep...