Dichotic listening as an index of lateralization of speech perception in familial risk children with and without dyslexia

Age-Related Dichotic Listening Skills in Impaired and Non-Impaired Readers: A Comparative Study

Dichotic listening is the high-level auditory process which enables the perception of different verbal stimuli delivered simultaneously to the right and left ears (binaural integration), as well as the perception of a verbal stimulus presented to one ear while ignoring a different stimulus in the other ear (binaural separation). Deficits in central auditory processing have been reported in children with learning disabilities. The present study aimed to compare dichotic listening performances in right-handed impaired readers (IR) and non-impaired readers (non-IR) according to age. For this, a cross-sectional study was conducted in 120 IR (56 males and 64 females) divided into five age groups and 120 non-IR (63 male and 57 female) matched on chronological age (8 to 9 years; 9 to 10 years; 10 to 12 years; 12 to 18 years; adult). They were tested for binaural integration and binaural separation, allowing for the calculation of dichotic aptitude (DA), ear prevalence (EP), and attentional shift index (ASI). A series of ANOVAs showed an effect of age and of the reading group for all the dichotic-related measures, except for EP. Binaural separation scores were lower in IR who also showed more intrusive responses compared to non-IR. These intrusive responses, which were more frequent on the right ear for IR, decreased with age in both groups. Overall, these results suggest that dichotic listening scores improve with age as the central auditory pathways mature. However, whatever the age, performances are lower in IR than in non-IR. This might be explained by an incomplete maturation of the auditory pathways in IR; an early start for long-term follow-up and auditory training is suggested.

Neurophysiological Evaluation of Right-Ear Advantage During Dichotic Listening

Right-ear advantage refers to the observation that when two different speech stimuli are simultaneously presented to both ears, listeners report stimuli more correctly from the right ear than the left. It is assumed to result from prominent projection along the auditory pathways to the contralateral hemisphere and the dominance of the left auditory cortex for the perception of speech elements. Our study aimed to investigate the role of attention in the right-ear advantage. We recorded magnetoencephalography data while participants listened to pairs of Japanese two-syllable words (namely, "/ta/ /ko/" or "/i/ /ka/"). The amplitudes of the stimuli were modulated at 35 Hz in one ear and 45 Hz in the other. Such frequency-tagging allowed the selective quantification of left and right auditory cortex responses to left and right ear stimuli. Behavioral tests confirmed the right-ear advantage, with higher accuracy for stimuli presented to the right ear than to the left. The amplitude of the auditory steady-state response was larger when attending to the stimuli compared to passive listening. We detected a correlation between the attention-related increase in the amplitude of the auditory steady-state response and the laterality index of behavioral accuracy. The right-ear advantage in the free-response dichotic listening was also found in neural activities in the left auditory cortex, suggesting that it was related to the allocation of attention to both ears.

Dichotic listening is associated with phonological awareness in Australian aboriginal children with otitis media: A remote community-based study

OBJECTIVE

Recent literature has highlighted a link between hearing loss as a result of otitis media in the early years of life and impacted binaural processing skills in later childhood. Such findings are of particular relevance to Indigenous Australian children, who tend to experience otitis media earlier in life and for longer periods than their non-Indigenous counterparts. There is also growing interest in the effects of reduced auditory processing ability on a child's early learning of language and, specifically, on phonological awareness that contributes to word reading skills. The aim of the present study was to determine the association between hearing thresholds, dichotic listening skills and phonological awareness in children with pervasive otitis media (OM) from remote Indigenous communities of Australia who generally do not speak English as a first language.

METHODS

Participants included one hundred and one children between the ages of 4.8-7.9 years (mean 6.1 years) from three separate remote Northern Territory communities. Evaluations included otoscopy, air conduction PTA, and tympanometry. All children were also assessed on the Dichotic Digits difference test (DDdT) and the Foundations of Early Literacy Assessment (FELA), assessing children's dichotic listening and phonological awareness respectively.

RESULTS

The results showed that 56% of the children had middle ear dysfunctions (type B and type C on tympanometry results) in at least one ear on the day. Partial correlation showed a significant correlation, between dichotic scores and FELA with age as covariate (r = 0.45, p < 0.001). One way ANOVA showed females exhibited a significantly higher performance compared to males on FELA [F (1, 99) = 5.47, p = 0.021]. The overall regression model was found to be significant in predicting total FELA scores [F (7, 77) = 7.56, p < 0.0005]. Age and gender as well as dichotic listening scores explain 40.7% of the variance.

CONCLUSIONS

The results reinforce the importance of managing the ear health of Indigenous children, clarifying the impact this has on listening and phonological awareness. These findings highlight the importance of evaluating children's listening abilities, and how poor listening can impact phonological awareness. The findings have important implications for ensuring optimal listening and learning conditions in schools in remote NT communities.

Auditive training effects from a dichotic listening app in children with dyslexia

Dichotic listening (DL) taps information on the brain's language laterality, processing, and attention. Research has shown that DL responses in dyslexia deviate from the typical pattern. Here, effects of DL training and its correspondence to rapid naming (RAN) and digit span (DS) in typical children and children with dyslexia were assessed. Three groups of third graders participated: two training groups, control training (CT) and dyslexia training (DT), and a control group that received no training (control no training, CnT). All took part in testing pretraining and posttraining. DL measures were on laterality, response scores, and attention. The three groups showed different response patterns: minor changes in CnT, change in all measures in CT, and some changes in DT. RAN and DS scores correlated significantly with some of the DL measures, especially with the attention scores. Our findings support arguments that brain architecture for language in dyslexia is lateralised in the same way as in children without dyslexia. However, the ability to modulate attention during DL is weaker in dyslexia than in typically developing children. A training-induced normalisation of lateralisation was observed in free recall in the dyslexia group, which suggests that DL training may be a promising intervention approach.