Auditory processing disorder in children: the value of a multidisciplinary assessment.

PURPOSE: Auditory processing disorder (APD) may affect 0.2-5% of the paediatric population. The diagnosis of APD remains difficult because of polymorphic symptoms possibly entangled with other difficulties. The purpose of this study was to evaluate a new multi-disciplinary assessment in the French language. METHODS: The battery of tests was composed of: (a) APD targeted speech assessment: speech perception in noise, a dichotic test, temporal processing tests (patterns); (b) Psychometric assessment: sustained auditory attention, sustained visual attention, evaluation of cognitive functions; (c) phonemic identification and discrimination; (d) ENT examination, tonal and vocal audiometry and ABR recordings. The diagnosis was made if two of the targeted speech tests were 2 standard deviations (SDs) below the mean or if only one of the tests was 3 SDs below. The auditory attention tests, as well as the phonemic identification and discrimination tests were complementary to the diagnostic battery. However, they did not allow for the diagnosis of APD. RESULTS: 50 children suspected of APD benefited from this protocol, and 12 were excluded from the study. A diagnosis of APD was confirmed in 17 children (45%). 59% of the patients had associated disorders. The most effective tests for diagnosing APD were dichotic testing (p = 0.001) and pattern recognition (frequency, p = 0.001). The sustained auditory attention test (p = 0.01) and the phonemic identification and discrimination test reinforced the diagnosis of APD. CONCLUSION: It seems important to evaluate children suspected of APD with a multi-disciplinary protocol. It makes it possible to diagnose APD children, but also to identify attentional difficulties and cognitive disorders that may be associated.

Remediation of Allophonic Perception and Visual Attention Span in Developmental Dyslexia: A Joint Assay.

Categorical perception of phonemes and visual attention span are cognitive processes that contribute independently to poor reading skills in developmental dyslexia. We here explored whether training programs specifically targeting one or the other process do improve reading performance in dyslexic children. The dyslexic participants were trained using either the RapDys© program designed to improve phonemic perception or the MAEVA© program targeting visual attention span. Each participant was provided the two programs successively for intensive training. Results show specific effects of RapDys© on phonemic discrimination and pseudo-word reading. MAEVA© specifically improved visual attention span and irregular word reading. Phonemic awareness and regular word reading improved after application of both training programs, suggesting similar positive effects of both methods although effects of concomitant phonic training cannot be ruled out (as there was no control group). The overall findings suggest that both categorical perception and visual attention span remediation contribute to reading.

Is There a Relationship Between Speech Identification in Noise and Categorical Perception in Children With Dyslexia?

PURPOSE: Children with dyslexia have been suggested to experience deficits in both categorical perception (CP) and speech identification in noise (SIN) perception. However, results regarding both abilities are inconsistent, and the relationship between them is still unclear. Therefore, this study aimed to investigate the relationship between CP and the psychometric function of SIN perception. METHOD: Sixteen children with dyslexia, 16 chronological-age controls, and 16 reading-level controls were evaluated in CP of a voicing continuum and in consonant identification in both stationary and fluctuating noises. RESULTS: There was a small but significant impairment in speech identification performance of children with dyslexia in stationary noise compared with chronological age-matched controls (but not reading level-matched controls). However, their performance increased in a fluctuating background, hence suggesting normal masking and unmasking effects and preserved sensory processing of speech information. Regarding CP, location of the phoneme boundary differed in the children with dyslexia compared with both control groups. However, scrutinizing individual profiles failed to reveal consistently poor performance in SIN and CP tasks. In addition, there was no significant correlation between CP, SIN perception, and reading scores in the group with dyslexia. CONCLUSIONS: The relationship between the SIN deficit and CP, and how they potentially affect reading in children with dyslexia, remains unclear. However, these results are inconsistent with the notion that children with dyslexia suffer from a low-level temporal processing deficit and rather suggest a role of nonsensory (e.g., attentional) factors in their speech perception difficulties.

Relationships between Categorical Perception of Phonemes, Phoneme Awareness, and Visual Attention Span in Developmental Dyslexia.

We tested the hypothesis that the categorical perception deficit of speech sounds in developmental dyslexia is related to phoneme awareness skills, whereas a visual attention (VA) span deficit constitutes an independent deficit. Phoneme awareness tasks, VA span tasks and categorical perception tasks of phoneme identification and discrimination using a d/t voicing continuum were administered to 63 dyslexic children and 63 control children matched on chronological age. Results showed significant differences in categorical perception between the dyslexic and control children. Significant correlations were found between categorical perception skills, phoneme awareness and reading. Although VA span correlated with reading, no significant correlations were found between either categorical perception or phoneme awareness and VA span. Mediation analyses performed on the whole dyslexic sample suggested that the effect of categorical perception on reading might be mediated by phoneme awareness. This relationship was independent of the participants' VA span abilities. Two groups of dyslexic children with a single phoneme awareness or a single VA span deficit were then identified. The phonologically impaired group showed lower categorical perception skills than the control group but categorical perception was similar in the VA span impaired dyslexic and control children. The overall findings suggest that the link between categorical perception, phoneme awareness and reading is independent from VA span skills. These findings provide new insights on the heterogeneity of developmental dyslexia. They suggest that phonological processes and VA span independently affect reading acquisition.

Altitude and seasonality impact on sleep in Antarctica.

BACKGROUND: This study investigates the effects of seasonality and altitude on sleep in extreme Antarctic conditions. METHODS: During summer and winter periods, 24 h of actimetric recordings were obtained at two different research stations, Dumont d'Urville (sea level altitude) and Concordia (corrected altitude 12,467 ft or 3800 m). RESULTS: During daytime, there were no altitude- or season-related differences in time spent at work, energy expenditure, or number of walking steps. During the nighttime however, total sleep time was longer (m = 427.4; SD = 42.4), sleep efficiency higher (m = 90; SD = 4.8), and wake after sleep onset shorter (m = 42.2; SD = 28.7) at sea level. Additionally, sleep fragmentation episodes and energy expenditure were higher during summer than winter periods. DISCUSSION: Our results show that dramatic variations in light exposure are not the only main factor affecting sleep quality in Antarctica, as altitude also markedly impacted sleep in these conditions. The effect of altitude-induced hypoxia should be taken into account in future investigations of sleep in extreme environments.

Review of neural rehabilitation programs for dyslexia: how can an allophonic system be changed into a phonemic one?

Neural investigations suggest that there are three possible core deficits in dyslexia: phonemic, grapho-phonemic, and graphemic. These investigations also suggest that the phonemic deficit resides in a different mode of speech perception which is based on allophonic (subphonemic) units rather than phonemic units. Here we review the results of remediation methods that tap into each of these core deficits, and examine how the methods that tap into the phonemic deficit might contribute to the remediation of allophonic perception. Remediation of grapho-phonemic deficiencies with a new computerized phonics training program (GraphoGame) might be able to surpass the limits of classical phonics training programs, particularly with regard to reading fluency. Remediation of visuo-graphemic deficiencies through exposure to enhanced letter spacing is also promising, although children with dyslexia continued to read more slowly than typical readers after this type of training. Remediation of phonemic deficiencies in dyslexia with programs based solely on phonemic awareness has a limited impact on reading. This might be due to the persistence of a covert deficit in phonemic perception. Methods based on slowed speech enhance the perception not only of phonemic features but also of allophonic features, and this is probably why they have not been found to be effective in meta-analyses. Training of phonemic perception with a perceptual fading paradigm, a method that improves precision in identification and discrimination around phonemic boundaries, has yielded promising results. However, studies with children at risk for dyslexia and dyslexic adults have found that even when behavioral data do not reflect allophonic perception, it can nevertheless be present in neural recordings. Further investigations should seek to confirm that the perceptual fading paradigm is beneficial for reading, and that it renders perception truly phonemic.

Is the auditory evoked P2 response a biomarker of learning?

Even though auditory training exercises for humans have been shown to improve certain perceptual skills of individuals with and without hearing loss, there is a lack of knowledge pertaining to which aspects of training are responsible for the perceptual gains, and which aspects of perception are changed. To better define how auditory training impacts brain and behavior, electroencephalography (EEG) and magnetoencephalography (MEG) have been used to determine the time course and coincidence of cortical modulations associated with different types of training. Here we focus on P1-N1-P2 auditory evoked responses (AEP), as there are consistent reports of gains in P2 amplitude following various types of auditory training experiences; including music and speech-sound training. The purpose of this experiment was to determine if the auditory evoked P2 response is a biomarker of learning. To do this, we taught native English speakers to identify a new pre-voiced temporal cue that is not used phonemically in the English language so that coinciding changes in evoked neural activity could be characterized. To differentiate possible effects of repeated stimulus exposure and a button-pushing task from learning itself, we examined modulations in brain activity in a group of participants who learned to identify the pre-voicing contrast and compared it to participants, matched in time, and stimulus exposure, that did not. The main finding was that the amplitude of the P2 auditory evoked response increased across repeated EEG sessions for all groups, regardless of any change in perceptual performance. What's more, these effects are retained for months. Changes in P2 amplitude were attributed to changes in neural activity associated with the acquisition process and not the learned outcome itself. A further finding was the expression of a late negativity (LN) wave 600-900 ms post-stimulus onset, post-training exclusively for the group that learned to identify the pre-voiced contrast.

Sleep may not benefit learning new phonological categories.

It is known that sleep participates in memory consolidation processes. However, results obtained in the auditory domain are inconsistent. Here we aimed at investigating the role of post-training sleep in auditory training and learning new phonological categories, a fundamental process in speech processing. Adult French-speakers were trained to identify two synthetic speech variants of the syllable /d∂/ during two 1-h training sessions. The 12-h interval between the two sessions either did (8 p.m. to 8 a.m. ± 1 h) or did not (8 a.m. to 8 p.m. ± 1 h) included a sleep period. In both groups, identification performance dramatically improved over the first training session, to slightly decrease over the 12-h offline interval, although remaining above chance levels. Still, reaction times (RT) were slowed down after sleep suggesting higher attention devoted to the learned, novel phonological contrast. Notwithstanding, our results essentially suggest that post-training sleep does not benefit more than wakefulness to the consolidation or stabilization of new phonological categories.

Auditory steady-state evoked potentials vs. compound action potentials for the measurement of suppression tuning curves in the sedated dog puppy.

Auditory steady-state evoked potential (ASSEP) tuning curves were compared to compound action potential (CAP) tuning curves, both measured at 2 Hz, using sedated beagle puppies. The effect of two types of masker (narrowband noise and sinusoidal) on the tuning curve parameters was assessed. Whatever the masker type, CAP tuning curve parameters were qualitatively and quantitatively similar to the ASSEP ones, with a similar inter-subject variability, but with a greater incidence of upward tip displacement. Whatever the procedure, sinusoidal maskers produced sharper tuning curves than narrow-band maskers. Although these differences are not likely to have significant implications for clinical work, from a fundamental point of view, their origin requires further investigations. The same amount of time was needed to record a CAP and an ASSEP 13-point tuning curve. The data further validate the ASSEP technique, which has the advantages of having a smaller tendency to produce upward tip shifts than the CAP technique. Moreover, being non invasive, ASSEP tuning curves can be easily repeated over time in the same subject for clinical and research purposes.

Effect of presentation level on diagnosis of dead regions using the threshold equalizing noise test.

The effect of the level of threshold equalizing noise (TEN) on the diagnosis of dead regions (DRs) was investigated. Participants comprised 23 adults with sensorineural hearing impairment. Masked thresholds were measured monaurally with TEN at 60, 70, 80, and 90 dB HL/ERB(N). Absolute and masked thresholds (with TEN at 80 dB HL/ERB(N)) were retested. The diagnosis was unaffected by TEN level at any frequency for eight of the 13 participants who met the criteria for a DR. For four of the latter, increasing the TEN level changed the diagnosis from DR to no DR, mainly at 1.5 kHz, corresponding to the edge frequency, f(e), of the DR. For one participant with a low-frequency DR, increasing the TEN level changed the diagnosis from no DR to DR, only at 1 kHz. The changes with level were too large to be explained in terms of test repeatability. Overall, the results of the TEN test are usually not affected by TEN level, except for test frequencies close to f(e) when absolute thresholds are near-normal for frequencies adjacent to f(e).