The Relative Contribution of Cochlear Synaptopathy and Reduced Inhibition to Age-Related Hearing Impairment for People With Normal Audiograms.

Older people often show auditory temporal processing deficits and speech-in-noise intelligibility difficulties even when their audiogram is clinically normal. The causes of such problems remain unclear. Some studies have suggested that for people with normal audiograms, age-related hearing impairments may be due to a cognitive decline, while others have suggested that they may be caused by cochlear synaptopathy. Here, we explore an alternative hypothesis, namely that age-related hearing deficits are associated with decreased inhibition. For human adults (N = 30) selected to cover a reasonably wide age range (25-59 years), with normal audiograms and normal cognitive function, we measured speech reception thresholds in noise (SRTNs) for disyllabic words, gap detection thresholds (GDTs), and frequency modulation detection thresholds (FMDTs). We also measured the rate of growth (slope) of auditory brainstem response wave-I amplitude with increasing level as an indirect indicator of cochlear synaptopathy, and the interference inhibition score in the Stroop color and word test (SCWT) as a proxy for inhibition. As expected, performance in the auditory tasks worsened (SRTNs, GDTs, and FMDTs increased), and wave-I slope and SCWT inhibition scores decreased with ageing. Importantly, SRTNs, GDTs, and FMDTs were not related to wave-I slope but worsened with decreasing SCWT inhibition. Furthermore, after partialling out the effect of SCWT inhibition, age was no longer related to SRTNs or GDTs and became less strongly related to FMDTs. Altogether, results suggest that for people with normal audiograms, age-related deficits in auditory temporal processing and speech-in-noise intelligibility are mediated by decreased inhibition rather than cochlear synaptopathy.

Auditory temporal resolution and backward masking in musicians with absolute pitch.

Among the many questions regarding the ability to effortlessly name musical notes without a reference, also known as absolute pitch, the neural processes by which this phenomenon operates are still a matter of debate. Although a perceptual subprocess is currently accepted by the literature, the participation of some aspects of auditory processing still needs to be determined. We conducted two experiments to investigate the relationship between absolute pitch and two aspects of auditory temporal processing, namely temporal resolution and backward masking. In the first experiment, musicians were organized into two groups according to the presence of absolute pitch, as determined by a pitch identification test, and compared regarding their performance in the Gaps-in-Noise test, a gap detection task for assessing temporal resolution. Despite the lack of statistically significant difference between the groups, the Gaps-in-Noise test measures were significant predictors of the measures for pitch naming precision, even after controlling for possible confounding variables. In the second experiment, another two groups of musicians with and without absolute pitch were submitted to the backward masking test, with no difference between the groups and no correlation between backward masking and absolute pitch measures. The results from both experiments suggest that only part of temporal processing is involved in absolute pitch, indicating that not all aspects of auditory perception are related to the perceptual subprocess. Possible explanations for these findings include the notable overlap of brain areas involved in both temporal resolution and absolute pitch, which is not present in the case of backward masking, and the relevance of temporal resolution to analyze the temporal fine structure of sound in pitch perception.

Neural synchronization and intervention in pre-readers who later on develop dyslexia.

A growing number of studies has investigated temporal processing deficits in dyslexia. These studies largely focus on neural synchronization to speech. However, the importance of rise times for neural synchronization is often overlooked. Furthermore, targeted interventions, phonics-based and auditory, are being developed, but little is known about their impact. The current study investigated the impact of a 12-week tablet-based intervention. Children at risk for dyslexia received phonics-based training, either with (n = 31) or without (n = 31) auditory training, or engaged in active control training (n = 29). Additionally, neural synchronization and processing of rise times was longitudinally investigated in children with dyslexia (n = 26) and typical readers (n = 52) from pre-reading (5 years) to beginning reading age (7 years). The three time points in the longitudinal study correspond to intervention pre-test, post-test and consolidation, approximately 1 year after completing the intervention. At each time point neural synchronization was measured to sinusoidal stimuli and pulsatile stimuli with shortened rise times at syllable (4 Hz) and phoneme rates (20 Hz). Our results revealed no impact on neural synchronization at syllable and phoneme rate of the phonics-based and auditory training. However, we did reveal atypical hemispheric specialization at both syllable and phoneme rates in children with dyslexia. This was detected even before the onset of reading acquisition, pointing towards a possible causal rather than consequential mechanism in dyslexia. This study contributes to our understanding of the temporal processing deficits underlying the development of dyslexia, but also shows that the development of targeted interventions is still a work in progress.

Neuromodulation of the left auditory cortex with transcranial direct current stimulation (tDCS) has no effect on the categorical perception of speech sounds.

Temporal cue analysis in auditory stimulus is essential in the perception of speech sounds. The effect of transcranial direct current stimulation (tDCS) on auditory temporal processing remains unclear. In this study, we examined whether tDCS applied over the left auditory cortex (AC) has a polarity-specific behavioral effect on the categorical perception of speech sounds whose temporal features are modulated. Sixteen healthy volunteers in each group were received anodal, cathodal, or sham tDCS. A phonetic categorization task including auditory stimuli with varying voice onset time was performed before and during tDCS, and responses were analyzed. No statistically significant difference was observed between groups (anode, cathode, sham) and within the groups (pre-tDCS, during tDCS) in comparisons of the slope parameter of the identification function obtained from the phonetic categorization task data. Our results show that a single-session application of tDCS over the left AC does not significantly affect the categorical perception of speech sounds.

Evidence of Validity and Normative Values of a New Auditory Backward Masking Test.

There are still no valid, clinically feasible instruments to assess backward masking (BM), an auditory temporal processing (ATP) phenomenon. The aim of this study was to develop, standardize and present evidence of validity for a behavioral test for BM assessment. Young adults were submitted to a BM test (BMT), where they were asked to identify a 1000 Hz pure tone followed by a narrowband noise with interstimulus intervals of 0 to 400 ms and signal-to-noise ratio (SNR) between -20 and -30 dB. The correct response rate and target sound detection threshold were calculated, and the results compared with those of young adults with abnormal ATP tests and older adults. Diagnostic accuracy analyses were carried out. Young adults with normal ATP obtained an average correct response rate of 89 and 87% for SNR -20 and -30 dB, respectively, with average thresholds between 10 and 15 ms and no difference between the left and right ears. Results were more consistent at SNR -20 dB, and the best diagnostic accuracy was obtained for SNR -20 dB, with good specificity, but low sensitivity. Normative values were obtained for the BMT, which proved to be clinically feasible, with preliminary evidence of validity.

Age-related hearing loss is associated with alterations in temporal envelope processing in different neural generators along the auditory pathway.

People with age-related hearing loss suffer from speech understanding difficulties, even after correcting for differences in hearing audibility. These problems are not only attributed to deficits in audibility but are also associated with changes in central temporal processing. The goal of this study is to obtain an understanding of potential alterations in temporal envelope processing for middle-aged and older persons with and without hearing impairment. The time series of activity of subcortical and cortical neural generators was reconstructed using a minimum-norm imaging technique. This novel technique allows for reconstructing a wide range of neural generators with minimal prior assumptions regarding the number and location of the generators. The results indicated that the response strength and phase coherence of middle-aged participants with hearing impairment (HI) were larger than for normal-hearing (NH) ones. In contrast, for the older participants, a significantly smaller response strength and phase coherence were observed in the participants with HI than the NH ones for most modulation frequencies. Hemispheric asymmetry in the response strength was also altered in middle-aged and older participants with hearing impairment and showed asymmetry toward the right hemisphere. Our brain source analyses show that age-related hearing loss is accompanied by changes in the temporal envelope processing, although the nature of these changes varies with age.

Temporal acuity is preserved in the auditory midbrain of aged mice.

Impaired temporal resolution of the central auditory system has long been suggested to contribute to speech understanding deficits in the elderly. However, it has been difficult to differentiate between direct age-related central deficits and indirect effects of confounding peripheral age-related hearing loss on temporal resolution. To differentiate this, we measured temporal acuity in the inferior colliculus (IC) of aged CBA/J and C57BL/6 mice, as a model of aging with and without concomitant hearing loss. We used two common measures of auditory temporal processing: gap detection as a measure of temporal fine structure and amplitude-modulated noise as a measure of envelope sensitivity. Importantly, auditory temporal acuity remained precise in the IC of old CBA/J mice when no or only minimal age-related hearing loss was present. In contrast, temporal acuity was only indirectly reduced by the presence of age-related hearing loss in aged C57BL/6 mice, not by affecting the brainstem precision, but by affecting the signal-to-noise ratio of the neuronal activity in the IC. This demonstrates that indirect effects of age-related peripheral hearing loss likely remain an important factor for temporal processing in aging in comparison to 'pure' central auditory decline itself. It also draws attention to the issue that the threshold difference between 'nearly normal' or 'clinically normal' hearing aging subjects in comparison to normal hearing young subjects still can have indirect effects on central auditory neural representations of temporal processing.

Ahead of maturation: Enhanced speech envelope training boosts rise time discrimination in pre-readers at cognitive risk for dyslexia.

Dyslexia has frequently been related to atypical auditory temporal processing and speech perception. Results of studies emphasizing speech onset cues and reinforcing the temporal structure of the speech envelope, that is, envelope enhancement (EE), demonstrated reduced speech perception deficits in individuals with dyslexia. The use of this strategy as auditory intervention might thus reduce some of the deficits related to dyslexia. Importantly, reading-skill interventions are most effective when they are provided during kindergarten and first grade. Hence, we provided a tablet-based 12-week auditory and phonics-based intervention to pre-readers at cognitive risk for dyslexia and investigated the effect on auditory temporal processing with a rise time discrimination (RTD) task. Ninety-one pre-readers at cognitive risk for dyslexia (aged 5-6) were assigned to two groups receiving a phonics-based intervention and playing a story listening game either with (n = 31) or without (n = 31) EE or a third group playing control games and listening to non-enhanced stories (n = 29). RTD was measured directly before, directly after and 1 year after the intervention. While the groups listening to non-enhanced stories mainly improved after the intervention during first grade, the group listening to enhanced stories improved during the intervention in kindergarten and subsequently remained stable during first grade. Hence, an EE intervention improves auditory processing skills important for the development of phonological skills. This occurred before the onset of reading instruction, preceding the maturational improvement of these skills, hence potentially giving at risk children a head start when learning to read. A video abstract of this article can be viewed at https://www.youtube.com/watch?v=e0BfT4dGXNA.

Effectiveness of the Auditory Temporal Ordering and Resolution Tests to Detect Central Auditory Processing Disorder in Adults With Evidence of Brain Pathology: A Systematic Review and Meta-Analysis.

Background: Auditory temporal processing tests are key clinical measures in order to diagnose central auditory processing disorder (CAPD). Although these tests have been used for decades, there is no up-to-date evidence to determine the effectiveness of detecting the abnormalities in central auditory processing in adults while the available national CAPD guidelines predominantly address CAPD in the pediatric population. Purpose: To determine the efficacy of the auditory temporal ordering tests [duration pattern test (DPT) and frequency pattern test (FPT)], and a temporal resolution test [gaps-in-noise (GIN) test] for detecting the central auditory processing abnormalities in adults with documented brain pathology. Research Design: Systematic reviews and meta-analyses. Study samples: Four databases, including PubMed, Web of Science, Embase, and Scopus, were systematically searched. The publications in the English language that recruited adults (above 16 years old) with pathologic brain conditions and described the diagnostic tests for auditory temporal processing were selected for review. Data Collections and Analysis: All data were systematically evaluated, extracted, categorized, and summarized in tables. The meta-analysis was done in order to determine the effectiveness of the DPT, FPT, and GIN tests. Results: The results showed significantly poorer performance of DPT and FPT, compared between participants with confirmed brain disease and normal controls, at the mean differences of percent correct -21.93 (95% CI, -26.58 to -17.29) and -31.37 (95% CI, -40.55 to -22.19), respectively. Subjects with brain pathology also performed poorer in GIN test at the mean difference of 3.19 milliseconds (95% CI, 2.51 to 3.87). Conclusion: The results from the meta-analysis provide evidence that DPT, FPT, and GIN clinical measures are effective in the diagnosis of CAPD in adults with neurological disorders. Poor performance on these tests is significantly related to the confirmed brain pathology. However, different units in results presentation and variety of testing strategies are limitations for this meta-analysis. The standard pattern of result reporting and international protocols test strategies should be developed in order to conduct better meta-analyses with a larger collection of suitable studies and less heterogeneity.

Neural Generators Underlying Temporal Envelope Processing Show Altered Responses and Hemispheric Asymmetry Across Age.

Speech understanding problems are highly prevalent in the aging population, even when hearing sensitivity is clinically normal. These difficulties are attributed to changes in central temporal processing with age and can potentially be captured by age-related changes in neural generators. The aim of this study is to investigate age-related changes in a wide range of neural generators during temporal processing in middle-aged and older persons with normal audiometric thresholds. A minimum-norm imaging technique is employed to reconstruct cortical and subcortical neural generators of temporal processing for different acoustic modulations. The results indicate that for relatively slow modulations (<50 Hz), the response strength of neural sources is higher in older adults than in younger ones, while the phase-locking does not change. For faster modulations (80 Hz), both the response strength and the phase-locking of neural sources are reduced in older adults compared to younger ones. These age-related changes in temporal envelope processing of slow and fast acoustic modulations are possibly due to loss of functional inhibition, which is accompanied by aging. Both cortical (primary and non-primary) and subcortical neural generators demonstrate similar age-related changes in response strength and phase-locking. Hemispheric asymmetry is also altered in older adults compared to younger ones. Alterations depend on the modulation frequency and side of stimulation. The current findings at source level could have important implications for the understanding of age-related changes in auditory temporal processing and for developing advanced rehabilitation strategies to address speech understanding difficulties in the aging population.

The internal time keeper: Causal evidence for the role of the cerebellum in anticipating regular acoustic events.

Most acoustic events in our environment do not appear randomly but are rather predictable due to the temporal regularity in that they occur. Besides sensory-related cortical areas, the cerebellum has been suggested as a key structure in temporal processing and in the anticipation of future events. Hence, patients with cerebellum lesions show impaired precision in temporal processing as reflected in the reduced ability to exploit temporal regularity. Using transcranial direct current stimulation (tDCS), we here aimed to draw further causal conclusions on the human cerebellum as functionally relevant in temporal processing of acoustic events. We focused on the electrophysiologic P3b, a large positive wave apparent in the electroencephalography (EEG), that represents encoding of task-relevant events and that has been demonstrated as sensitive to the exploitation of temporal regularities. Participants received 30 min of anodal, cathodal or sham tDCS over the cerebellum while they performed two oddball paradigms with different temporal regularities in that the acoustic stimuli were presented. Following clinical observations, we hypothesized that tDCS-effects will be present in the regular oddball paradigm only, thus, in the condition that allows anticipating the occurrence of subsequent stimuli. In result, we found that cathodal tDCS over the cerebellum reduced the P3b-amplitude specifically in response to target stimuli in the regular paradigm. Thereby, tDCS-induced changes mirror the effects of cerebellar lesions in clinical samples. Our data provides direct evidence for a causal link between the human cerebellum and auditory processing of temporal regularity and emphasize future work on a potential benefit of cerebellar-tDCS in clinical samples.

Noise-Induced Changes of the Auditory Brainstem Response to Speech-a Measure of Neural Desynchronisation?

It is commonly assumed that difficulty in listening to speech in noise is at least partly due to deficits in neural temporal processing. Given that noise reduces the temporal fidelity of the auditory brainstem response (ABR) to speech, it has been suggested that the speech ABR may serve as an index of such neural deficits. However, the temporal fidelity of ABRs, to both speech and non-speech sounds, is also known to be influenced by the cochlear origin of the response, as responses from higher-frequency cochlear regions are faster and more synchronous than responses from lower-frequency regions. Thus, if noise caused a reweighting of response contributions from higher- to lower-frequency cochlear regions, the temporal fidelity of the aggregate response should be reduced even in the absence of any changes in neural processing. This 'place mechanism' has been demonstrated for non-speech ABRs. The aim of this study was to test whether it also applies to speech ABRs. We used the so-called 'derived-band' method to isolate response contributions from frequency-limited cochlear regions. Broadband and derived-band speech ABRs were measured both in quiet and in noise. Whilst the noise caused significant changes to the temporal properties of the broadband response, its effects on the derived-band responses were mostly restricted to the response amplitudes. Importantly, the amplitudes of the higher-frequency derived-band responses were much more strongly affected than those of the lower-frequency responses, suggesting that the noise indeed caused a reweighting effect. Our results indicate that, as for non-speech ABRs, the cochlear place mechanism can represent a potentially substantial confound to speech-ABR-in-noise measurements.

Gaps-In-Noise Test Performance in Children with Speech Sound Disorder and Cognitive Difficulty.

BACKGROUND AND OBJECTIVES: The Gaps-In-Noise (GIN) test is a clinically effective measure of the integrity of the central auditory nervous system. The GIN procedure can be applied to a pediatric population above 7 years of age. The present study conducted the GIN test to compare the abilities of auditory temporal resolution among typically developing children, children with speech sound disorder (SSD), and children with cognitive difficulty (CD). SUBJECTS AND METHODS: Children aged 8 to 11 years-(total n=30) participated in this study. There were 10 children in each of the following three groups: typically developing children, children with SSD, and children with CD. The Urimal Test of Articulation and Phonology was conducted as a clinical assessment of the children's articulation and phonology. The Korean version of the Wechsler Intelligence Scale for Children-III (K-WISC-III) was administered as a screening test for general cognitive function. According to the procedure of Musiek, the pre-recorded stimuli of the GIN test were presented at 50 dB SL. The results were scored by the approximated threshold and the overall percent correct score (%). RESULTS: All the typically developing children had normal auditory temporal resolution based on the clinical cutoff criteria of the GIN test. The children with SSD or CD had significantly reduced gap detection performance compared to age-matched typically developing children. The children's intelligence score measured by the K-WISC-III test explained 37% of the variance in the percent-correct score. CONCLUSIONS: Children with SSD or CD exhibited poorer ability to resolve rapid temporal acoustic cues over time compared to the age-matched typically developing children. The ability to detect a brief temporal gap embedded in a stimulus may be related to the general cognitive ability or phonological processing.

Auditory temporal processing assessment in children with developmental stuttering.

OBJECTIVE: Stuttering is a developmental disorder of speech production with a dynamic and multifactorial nature. Scientific theories mentioned the role of auditory processing disorder in stuttering. Investigating the auditory processing in stuttering would provide insights into the mechanisms of stuttering. The details of basic auditory processing in children with stuttering (CWS) continue to remain uncertain. This study aimed to investigate the auditory temporal processing (ATP) in CWS and also its relationship with the stuttering severity. METHODS: The participants of this comparative cross-sectional study were 54 CWS and 63 children without stuttering (CWOS). All children were between 7 and 12 years old. ATP ability of the participants was measured using the Backward Masking (BM), Duration Pattern (DP), and Gap in Noise (GIN) tests. Then, the groups were compared in terms of ATP results. The correlation between the scores of these tests and stuttering severity was assessed. RESULTS: According to the results, CWS showed poorer performance on DP, BM and GIN tests when compared with CWOS. Moreover, the stuttering severity had a significant negative correlation with the DP scores and percentage of correct identification scores in GIN; whereas it had a significant positive correlation with the BM thresholds. CONCLUSIONS: The results showed that some CWS have ATP disorder, which could exacerbate their stuttering. These findings highlighted the role of ATP disorder in stuttering.

Speech Comprehension and Its Relation to Other Auditory Parameters in Elderly Patients With Tinnitus.

Deteriorated speech comprehension is a common manifestation of the age-related decline of auditory functions (presbycusis). It could be assumed that when presbycusis is accompanied by tinnitus, general hearing functions, and particularly comprehension of speech in quiet and speech in noise (SIN), will be significantly affected. In this study, speech comprehension ability and other parameters of auditory function were assessed in elderly subjects with (T, n = 25) and without (NT, n = 26) tinnitus, aiming for examination of both peripheral and central auditory processing. Apart from high-frequency audiograms in quiet and in background noise, speech recognition thresholds in silence or in competitive babble noise, and the ability to understand temporally gated speech (GS), we measured also sensitivity to frequency modulation (FM) and interaural delay, gap detection thresholds (GDT), or the difference limens of intensity. The results show that in elderly participants matched by age (mean ages around 68 years), cognitive status (median MoCA scores around 27), and hearing thresholds [median pure-tone averages (PTA) around 16 dB hearing loss (HL)], tinnitus per se has little influence on speech comprehension. The tinnitus patients also show similar GDT, sensitivity to interaural intensity difference, and sensitivity to FM as the NT subjects. Despite these similarities, nevertheless, significant differences in auditory processing have been found in the tinnitus participants: a worse ability to detect tones in noise, a higher sensitivity to intensity changes, and a higher sensitivity to interaural time differences. Additional correlation analyses further revealed that speech comprehension in the T subjects is dependent on the sensitivity to temporal modulation and interaural time delay (ITD), while these correlations are weak and non-significant in the NT subjects. Therefore, despite similarities in average speech comprehension and several other parameters of auditory function, elderly people with tinnitus exhibit different auditory processing, particularly at a suprathreshold level. The results also suggest that speech comprehension ability of elderly tinnitus patients relies more on temporal features of the sound stimuli, especially under difficult conditions, compared to elderly people without tinnitus.

Distinct effects of visual and auditory temporal processing training on reading and reading-related abilities in Chinese children with dyslexia.

This study aimed to examine the effects of temporal processing training on the reading abilities of Chinese children with dyslexia. In total, 69 Chinese children with dyslexia in grades three through six were recruited in Taiwan. The children were divided into the following three equal groups: (1) auditory temporal processing training group, (2) visual temporal processing training group, and (3) control group with no specific training. The participants in both training groups received instruction with identical durations (30-40 min), intensities (12 times in total), and frequencies (three to four times per week). The participants in the control group were asked to independently surf some specified websites using devices similar to those used by the two experimental groups for an identical duration, intensity, and frequency. Our results indicated that the two groups who received temporal processing training exhibited significant correlations among Chinese character reading, rapid naming, and corresponding reading-related abilities, while visual temporal processing served as a significant predictor of Chinese character reading ability even if all background data, reading-related abilities, and auditory temporal processing were introduced first. Additionally, significant interactions were found between the Groups and Tested sessions in all the measures, except for phonological awareness, confirming the distinct effects of different temporal processing on most measures involved in this study. Further simple main effects revealed that only those who received the visual temporal processing training gained benefits in the corresponding reading-related ability (i.e., orthographic knowledge) and far-transfer to Chinese character reading.

Time-Compressed Speech Identification Is Predicted by Auditory Neural Processing, Perceptuomotor Speed, and Executive Functioning in Younger and Older Listeners.

Older adults typically have difficulty identifying speech that is temporally distorted, such as reverberant, accented, time-compressed, or interrupted speech. These difficulties occur even when hearing thresholds fall within a normal range. Auditory neural processing speed, which we have previously found to predict auditory temporal processing (auditory gap detection), may interfere with the ability to recognize phonetic features as they rapidly unfold over time in spoken speech. Further, declines in perceptuomotor processing speed and executive functioning may interfere with the ability to track, access, and process information. The current investigation examined the extent to which age-related differences in time-compressed speech identification were predicted by auditory neural processing speed, perceptuomotor processing speed, and executive functioning. Groups of normal-hearing (up to 3000 Hz) younger and older adults identified 40, 50, and 60 % time-compressed sentences. Auditory neural processing speed was defined as the P1 and N1 latencies of click-induced auditory-evoked potentials. Perceptuomotor processing speed and executive functioning were measured behaviorally using the Connections Test. Compared to younger adults, older adults exhibited poorer time-compressed speech identification and slower perceptuomotor processing. Executive functioning, P1 latency, and N1 latency did not differ between age groups. Time-compressed speech identification was independently predicted by P1 latency, perceptuomotor processing speed, and executive functioning in younger and older listeners. Results of model testing suggested that declines in perceptuomotor processing speed mediated age-group differences in time-compressed speech identification. The current investigation joins a growing body of literature suggesting that the processing of temporally distorted speech is impacted by lower-level auditory neural processing and higher-level perceptuomotor and executive processes.

Auditory temporal processing, reading, and phonological awareness among aging adults.

Auditory temporal processing (ATP) has been related in the literature to both speech perception as well as reading and phonological awareness. In aging adults, it is known to be related to difficulties in speech perception. In the present study, we aimed to test whether an age-related deficit in ATP would also be accompanied by poor reading and phonological awareness. Thirty-eight aging adults were compared to 55 readers with dyslexia and 42 young normal readers on temporal order judgment (TOJ), speech perception, reading, and phonological awareness tests. Aging adults had longer TOJ thresholds than young normal readers, but shorter than readers with dyslexia; however, they had lower speech perception accuracy than both groups. Phonological awareness of the aging adults was better than readers with dyslexia, but poorer than young normal readers, although their reading accuracy was similar to that of the young controls. This is the first report on poor phonological awareness among aging adults. Suprisingly, it was not accompanied by difficulties in reading ability, and might instead be related to aging adults' difficulties in speech perception. This newly discovered relationship between ATP and phonological awareness among aging adults appears to extend the existing understanding of this relationship, and suggests it should be explored in other groups with ATP deficits.

Auditory temporal perceptual learning and transfer in Chinese-speaking children with developmental dyslexia.

Perceptual learning refers to the improvement of perceptual performance as a function of training. Recent studies found that auditory perceptual learning may improve phonological skills in individuals with developmental dyslexia in alphabetic writing system. However, whether auditory perceptual learning could also benefit the reading skills of those learning the Chinese logographic writing system is, as yet, unknown. The current study aimed to investigate the remediation effect of auditory temporal perceptual learning on Mandarin-speaking school children with developmental dyslexia. Thirty children with dyslexia were screened from a large pool of students in 3th-5th grades. They completed a series of pretests and then were assigned to either a non-training control group or a training group. The training group worked on a pure tone duration discrimination task for 7 sessions over 2 weeks with thirty minutes per session. Post-tests immediately after training and a follow-up test 2 months later were conducted. Analyses revealed a significant training effect in the training group relative to non-training group, as well as near transfer to the temporal interval discrimination task and far transfer to phonological awareness, character recognition and reading fluency. Importantly, the training effect and all the transfer effects were stable at the 2-month follow-up session. Further analyses found that a significant correlation between character recognition performance and learning rate mainly existed in the slow learning phase, the consolidation stage of perceptual learning, and this effect was modulated by an individuals' executive function. These findings indicate that adaptive auditory temporal perceptual learning can lead to learning and transfer effects on reading performance, and shed further light on the potential role of basic perceptual learning in the remediation and prevention of developmental dyslexia.

Dyslexia as a multi-deficit disorder: Working memory and auditory temporal processing.

Dyslexia is difficulty in acquiring reading skills despite adequate intelligence and sufficient reading opportunities. Its origin is still under debate. Studies usually focus on a singular cause for dyslexia; however, some researchers argue that dyslexia reflects multiple deficits. Two of the abilities under investigation in dyslexia are working memory (WM) and auditory temporal processing (ATP). In order to better evaluate the relative roles of WM and ATP in dyslexia, in the present study, we tested the contribution of WM and ATP to different types of reading performance and phonological awareness in dyslexia, using a multidimensional approach. Seventy-eight adults with dyslexia and 23 normal-reading adults performed WM and ATP tasks, as well as reading and phonological awareness tests. Readers with dyslexia showed poorer performance on all tests. Both WM and ATP were significant predictors of reading performance and phonological awareness among participants with dyslexia. Dividing participants with dyslexia according to their performance level on WM and ATP tasks revealed group differences in reading and phonological awareness tests. Both WM and ATP contribute to dyslexia, and varying levels of difficulties in both of these abilities are observed among this population. This is strong evidence in favor of the multi-deficit approach in dyslexia, and suggests that researchers should consider this approach in future studies of dyslexia.