Development and Evaluation of the Italian Version of the Dichotic Digit Test: Insights from 39 Normal-Hearing Children Aged 11 to 13 years.

BACKGROUND The dichotic digit test (DDT) is one of the tests for the behavioral assessment of central auditory processing. Dichotic listening tests are sensitive ways of assessing cortical structures, the corpus callossum, and binaural integration mechanisms, showing strong correlations with learning difficulties. The DDT is presently available in a number of languages, each appropriate for the subject's native language. However, there is presently no test in the Italian language. The goal of this study was to develop an Italian version of the one-pair dichotic digit test (DDT-IT) and analyze results in 39 normal-hearing Italian children 11 to 13 years old. We used 2 conditions of presentation: free recall and directed attention (left or right ear), and looked at possible effects of sex and ear side. MATERIAL AND METHODS This study involved 3 steps: creation of the stimuli, checking their quality with Italian speakers, and assessment of the DDT-IT in our subject pool. The study involved 39 children (26 girls and 13 boys), aged 11-13 years. All participants underwent basic audiological assessment, auditory brainstem response, and then DDT-IT. RESULTS Results under free recall and directed attention conditions were similar for right and left ears, and there were no sex or age effects. CONCLUSIONS The Italian version of DDT (DDT-IT) has been developed and its performance on 39 normal-hearing Italian children was assessed. We found there were no age or sex effects for either the free recall condition or the directed attention condition.

Opposite perceptual biases in analogous auditory and visual tasks are unique to consonant-vowel strings and are unlikely a consequence of repetition.

Despite wide reporting of a right ear (RE) advantage on dichotic listening tasks and a right visual field (RVF) advantage on visual half-field tasks, we know very little about the relationship between these perceptual biases. Previous studies that have investigated perceptual asymmetries for analogous auditory and visual consonant-vowel tasks have indicated a serendipitous finding: a RE advantage and a left visual field (LVF) advantage with poor cross-modal correlations. In this study, we examined the possibility that this LVF advantage for visual processing of consonant-vowel strings may be a consequence of repetition by examining perceptual biases in analogous auditory and visual tasks for both consonant-vowel strings and words. We replicated opposite perceptual biases for consonant-vowel strings (RE and LVF advantages). This did not extend to word stimuli where we found RE and RVF advantages. Furthermore, these perceptual biases did not differ across the three experimental blocks. Thus, we can firmly conclude that this LVF advantage is unique to consonant-vowel strings and is not a consequence of the repetition of a relatively limited number of stimuli. Finally, a test of covariances indicated no cross-modal relationships between laterality indices suggesting that perceptual biases are dissociable within individuals and cluster on mode of presentation.

Modality matters: Three auditory conflict tasks to measure individual differences in attention control.

Early work on selective attention used auditory-based tasks, such as dichotic listening, to shed light on capacity limitations and individual differences in these limitations. Today, there is great interest in individual differences in attentional abilities, but the field has shifted towards visual-modality tasks. Furthermore, most conflict-based tests of attention control lack reliability due to low signal-to-noise ratios and the use of difference scores. Critically, it is unclear to what extent attention control generalizes across sensory modalities, and without reliable auditory-based tests, an answer to this question will remain elusive. To this end, we developed three auditory-based tests of attention control that use an adaptive response deadline (DL) to account for speed-accuracy trade-offs: Auditory Simon DL, Auditory Flanker DL, and Auditory Stroop DL. In a large sample (N = 316), we investigated the psychometric properties of the three auditory conflict tasks, tested whether attention control is better modeled as a unitary factor or modality-specific factors, and estimated the extent to which unique variance in modality-specific factors contributed incrementally to the prediction of dichotic listening and multitasking performance. Our analyses indicated that the auditory conflict tasks have strong psychometric properties and demonstrate convergent validity with visual tests of attention control. Auditory and visual attention control factors were highly correlated (r = .81)-even after controlling for perceptual processing speed (r = .75). Modality-specific attention control factors accounted for unique variance in modality-matched criterion measures, but the majority of the explained variance was modality-general. The results suggest an interplay between modality-general attention control and modality-specific processing.

Auditory Attention Ability under Dichotic Dual-Task Situation in Adults with Listening Difficulties.

INTRODUCTION: Recent studies have reported poor cognition, such as attention and working memory, in adults with listening difficulties (LiD). However, they do not adequately describe the actual state of poor attention ability in adults with LiD. We examined the state of auditory attention in adults with and without LiD in tasks requiring multiple attention controls. METHODS: Twenty-one adults who had normal hearing but complained about LiD encountered during everyday life and 22 healthy controls were included. We presented a target detection task using an odd-ball format for one ear and a sentence repetition task for the other ear. In the target detection task, participants listened to the 1,000-Hz tone served as the standard stimulus, while they had to accept a 2,000-Hz tone presented as the deviant stimulus. In the sentence repetition task, short sentences were presented. The stimuli presented to them were played on a personal computer at the most comfortable level. The participants heard these stimuli through headphones. They were required to press a key for standard stimuli in the target detection task and repeat what they heard immediately in the repetition task. We compared the response accuracy for each ear task between adults with and without LiD. RESULTS: Our results showed that there were significant differences between the participant groups in the auditory dual-task under the dichotic listening situation. When examined individually, four adults with LiD had decreased scores in both the sentence repetition and target detection task, while the other nine participants showed a bias toward either task. Furthermore, the analysis of reaction time for pressing button revealed that the standard deviation of reaction time was extended in participants who scored poorly in either of the ear tasks. On the other hand, all adults without LiD were able to conduct the auditory dual-task exactly and promptly. CONCLUSION: The results suggest that adults with LiD have difficulties in appropriately allocating various cognitive abilities required for each task. We concluded that auditory attention is an important ability to conduct the auditory dual-task, and this is applicable for adults with LiD. Therefore, we believe that it is necessary to use auditory tests that require complex attentional abilities in listening, such as those required in daily life, to assess adults with LiD.

The use of the Feather Squadron to identify auditory processing disorders in South African children: a comparative study.

OBJECTIVE: Development of the Feather Squadron (FS) has created a cost-effective, accessible form of assessment through tele-audiology. As accessibility to reliable, cost-effective assessment of auditory processing (AP) skills is limited in South Africa (SA), this study aims to establish whether there is correlation between the FS and traditional tests of AP viz. Frequency Pattern and Dichotic Digits Test, and to establish its relevance to the SA population. DESIGN: Retrospective, within-subject, comparative design used to compare performance on the FS and the traditional tests. Data were considered in two ways: Firstly, using the traditional -2SD cut-off on some subtests of the FS compared to the same traditional tests, and secondly, by comparing the Z-scores obtained on the FS compared to Z-scores on the same traditional tests obtained by applying a double arcsine transformation. STUDY SAMPLE: Sixty-six subjects (35 males, 31 females) aged between 8.08 and 9.75 years (mean = 8.73; SD = 0.51) seen for AP assessments between 2016 and 2019. RESULTS: -2SD criteria yielded no significant association (p > 0.05). Z-score comparison suggested a statistically significant correlation (p < 0.05). CONCLUSION: A statistically significant correlation between certain subtests of FS with traditional tests of AP to merit its use in the SA population is suggested.

Language lateralization in very preterm children: associating dichotic listening to interhemispheric connectivity and language performance.

BACKGROUND: Language difficulties of very preterm (VPT) children might be related to weaker cerebral hemispheric lateralization of language. Language lateralization refers to the development of an expert region for language processing in the left hemisphere during the first years of life. Children born VPT might not develop such a dominant left hemisphere for language processing. A dichotic listening task may be a functional task to show the dominance of the left hemisphere during language processing. During this task, different acoustic events are simultaneously presented to both ears. Due to crossing fibers in the brain, right ear stimuli are transferred directly to the left hemisphere, and left ear stimuli are transferred first to the right hemisphere and then, through the corpus callosum (CC), to the left hemisphere. Dichotic listening typically shows a right ear advantage, assuming to reflect left hemispherical language dominance. The CC, in particular the splenium, is associated with auditory processing and is considered important for language lateralization. The objective of this work was to explore whether dichotic listening performance in school-aged VPT children are associated with language performance and interhemispheric connectivity. METHODS: This is a cross-sectional study of 58 VPT children and 30 full term controls at age 10 years. Language performance and dichotic digit test (DDT) were assessed. In 44 VPT children, additionally diffusion weighted imaging (DWI) was performed using a 3 T MRI scanner. Fractional anisotropy (FA) and mean diffusivity (MD) values of the splenium of the CC were extracted. RESULTS: Poorer right ear DDT scores were associated with poorer language performance in VPT children only (p = 0.015). Association between right ear DDT scores and MD of the splenium approached the level of significance (p = 0.051). CONCLUSIONS: These results support the hypothesis that poor language performance in VPT children may be a consequence of weaker lateralized language organization, due to a poorly developed splenium of the CC. Dichotic listening may reflect the level of language lateralization in VPT children. IMPACT: Poor language performance in VPT children may be a consequence of weaker lateralized language organization, due to a poorly developed splenium of the CC. Dichotic listening performance may reflect the level of language lateralization in VPT children and right ear scores of a dichotic listening task are associated with both the splenium of the corpus callosum and language performance. If our results could be validated in future research, it suggests that poor CC development may indicate VPT children at risk for long-term language problems.

Dichotic listening abilities among liturgical teachers of the Ethiopian Orthodox Church.

This study examines patterns of ear advantage and attentional capacity among religious teachers of the Ethiopian Orthodox Church versus adults who are not religious teachers. Religious education, rooted mainly in Christianity and Islam, has a long history in Ethiopia. Most of such education has been practised through recitations and oral presentations, which demand perceptual vigour particularly on the part of the teachers. The present study employed a dichotic listening paradigm, using monosyllabic word and CV-syllables listening tasks, administered in three attentional conditions: non-forced (NF), forced-right (FR) and forced-left (FL). 54 right-handed male adults (27 teachers and 27 non-teachers) served as participants. Percentages of correct responses per ear, as well as Laterality Index (LI) were calculated and analysed using a repeated measures analysis of variance (ANOVA) statistical procedure. Results showed that, on both listening tasks, the religious teachers demonstrated a higher ear advantage in all conditions, indicative of stronger language asymmetry (in non-forced condition) and better ability to focus on one specific ear (in forced conditions). The findings of the present study are very much in support of the theory of neuroplasticity in human cognition (Konorski, 1948).

Association Between the Right Ear Advantage in Dichotic Listening and Interaural Differences in Sensory Processing at Lower Levels of the Auditory System in Older Adults.

OBJECTIVE: Current evidence suggests that an enhanced right ear advantage (REA) in dichotic listening (DL) among older adults may originate from age-related structural changes in the corpus callosum and age-related decline in cognitive processes. Less is known about the effect of information processing at lower portions of the auditory system on DL performance. The present study investigates whether interaural differences (ID) in sensory processing at lower levels of the auditory system are associated with the magnitude of the REA in DL among older adults. DESIGN: Sixty-eight older adults participated in the study. Participants were assessed with a DL test using nonforced (NF) and forced attention paradigms. Hearing sensitivity, transient-evoked otoacoustic emission (TEOAE), contralateral suppression of TEOAE, a proxy measure of medial olivocochlear activation, and auditory brainstem response to speech stimuli (speech-ABR) were tested in both ears separately. The ID in sensory processing at lower levels of the auditory system was derived by calculating the difference between the RE and LE for each auditory measure. Bivariate and multivariate regression models were performed. One multivariate model for each DL paradigm (NF and forced attention) was independently constructed. Measures of cognitive speed of processing and cognitive flexibility were accounted for in the regression models. RESULTS: For both multivariate regression models, ID in pure-tone thresholds and ID in MOC suppression of TEOAE were significantly associated with the magnitude of the REA for DL among older adults. Cognitive measures of speed of processing and cognitive flexibility also contributed to the magnitude of the REA. CONCLUSION: These results suggest that ID in sensory processing at lower levels of the auditory system account, at least in part, for the increased magnitude of the REA in DL among older adults.

Binaural Frequency Modulation Detection in School-Age Children, Young Adults, and Older Adults: Effects of Interaural Modulator Phase.

OBJECTIVES: The purpose of this study was to measure low-rate binaural frequency modulation (FM) detection across the lifespan as a gauge of temporal fine structure processing. Children and older adults were expected to perform more poorly than young adults but for different reasons. DESIGN: Detection of 2-Hz FM carried by a 500-Hz pure tone was measured for modulators that were either in-phase or out-of-phase across ears. Thresholds were measured in quiet and in noise. Participants were school-age children (n = 44), young adults (n = 11), and older adults (n = 17) with normal or near-normal hearing. RESULTS: Thresholds were lower for out-of-phase than in-phase modulators among all listening groups. Detection thresholds improved with child age, with larger effects of age for dichotic than diotic FM. Introduction of masking noise tended to elevate thresholds; this effect was larger for the dichotic condition than the diotic condition, and larger for older adults than young adults. In noise, young adults received the greatest dichotic benefit, followed by older adults, then young children. The relative effects of noise on dichotic benefit did not differ for young adults compared to young children and older adults; however, young children saw greater reduction in benefit due to noise than older adults. CONCLUSION: The difference in dichotic benefit between children and young adults is consistent with maturation of central auditory processing. Differences in the effect of noise on dichotic benefit in young children and older adults support the idea that different factors or combinations of factors limit performance in these two groups. Although dichotic FM detection appears to be more sensitive to the effects of development and aging than diotic FM detection, the positive correlation between diotic and dichotic FM detection thresholds for all listeners suggests contribution of one or more factors common to both conditions.

Assessing the reliability of an online behavioural laterality battery: A pre-registered study.

Studies of cerebral lateralization often involve participants completing a series of perceptual tasks under laboratory conditions. This has constrained the number of participants recruited in such studies. Online testing can allow for much larger sample sizes but limits the amount of experimental control that is feasible. Here we considered whether online testing could give valid and reliable results on four tasks: a rhyme decision visual half-field task, a dichotic listening task, a chimeric faces task, and a finger tapping task. We recruited 392 participants, oversampling left-handers, who completed the battery twice. Three of the tasks showed evidence of both validity and reliability, insofar as they showed hemispheric advantages in the expected direction and test-retest reliability of at least r = .75. The reliability of the rhyme decision task was less satisfactory (r = .62). We also confirmed a prediction that extreme left-handers were more likely to depart from typical lateralization. Lateralization across the two language tasks (dichotic listening and rhyme judgement) was weakly correlated, but unrelated to lateralization on the chimeric faces task. We conclude that three of the tasks, dichotic listening, chimeric faces and finger tapping, show considerable promise for online evaluation of cerebral lateralization.

Certain, but incorrect: on the relation between subjective certainty and accuracy in sound localisation.

When asked to identify the position of a sound, listeners can report its perceived location as well as their subjective certainty about this spatial judgement. Yet, research to date focused primarily on measures of perceived location (e.g., accuracy and precision of pointing responses), neglecting instead the phenomenological experience of subjective spatial certainty. The present study aimed to investigate: (1) changes in subjective certainty about sound position induced by listening with one ear plugged (simulated monaural listening), compared to typical binaural listening and (2) the relation between subjective certainty about sound position and localisation accuracy. In two experiments (N = 20 each), participants localised single sounds delivered from one of 60 speakers hidden from view in front space. In each trial, they also provided a subjective rating of their spatial certainty about sound position. No feedback on response was provided. Overall, participants were mostly accurate and certain about sound position in binaural listening, whereas their accuracy and subjective certainty decreased in monaural listening. Interestingly, accuracy and certainty dissociated within single trials during monaural listening: in some trials participants were certain but incorrect, in others they were uncertain but correct. Furthermore, unlike accuracy, subjective certainty rapidly increased as a function of time during the monaural listening block. Finally, subjective certainty changed as a function of perceived location of the sound source. These novel findings reveal that listeners quickly update their subjective confidence on sound position, when they experience an altered listening condition, even in the absence of feedback. Furthermore, they document a dissociation between accuracy and subjective certainty when mapping auditory input to space.

Dichotic listening using Mandarin CV-words of six plosives and vowel /a/.

OBJECTIVE: Available data on dichotic listening using tonal Chinese words have been limited, and conflicting results on a right-ear advantage (REA) have been reported. The current study developed a set of Mandarin CV-words based on the Bergen dichotic listening paradigm. DESIGN: The test materials consisted of two sets of stimuli. The English set, derived from the iDichotic application, consisted of six nonsense syllables with plosives conjugated to /a/. The Mandarin set had these 6 CV-syllables spoken as real words according to the Mandarin phonology. Study sample: Forty young, native Mandarin speakers were tested dichotically with both sets of test materials. Twenty participants were right-handed, and the other twenty were left-handed. Fourteen participants were randomly selected to repeat the test with the Mandarin set. RESULTS: The mean difference of correct recognition responses between two ears indicated a REA with both sets of stimuli for the right-handers, but not for left-handers. For the right-handers, performance with the Mandarin set was significantly better than performance with the English set. Dichotic listening with the Mandarin set had strong correlation between two time points, r = 0.8. CONCLUSIONS: Performance using the Mandarin set is reliable in dichotic listening; a REA is observed for the right-handers.

Correlating performance on the Listening in Spatialised Noise - Sentences test (LiSN-S) with the Listening in Spatialised Noise - Universal test (LiSN-U).

Objective: The aim of this study was to correlate 6- to 7-year-old children's results on each condition of the Listening in Spatialised Noise - Sentences test (LiSN-S) with the new language-independent version, the Listening in Spatialised Noise - Universal test (LiSN-U), to examine the strength of the relationship between them and with memory in a small sample of typically developing children.Design: Correlational analysis.Study samples: Sixteen typically developing 6- to 7-year-old children completed the LiSN-S and LiSN-U as well as the Test of Auditory Processing Skills - Third Edition (TAPS-3) number memory forward and reversed subtests which assess short-term memory and working memory, respectively.Results: Moderate positive correlations were found between LiSN-S and LiSN-U spatially separated conditions (though this did not reach significance), and co-located conditions. Correlations between the LiSN-S and LiSN-U conditions and number memory forward and reversed subtests were not significant.Conclusion: This study shows a moderate relationship between the LiSN-S and LiSN-U when the distractors and target speech are co-located. A study with a larger sample of participants is needed to further understand the relationship between the two tests, especially for the spatially separated condition.

Detection of hearing problems in Aboriginal and Torres strait islander children: a comparison between clinician-administered and self-administrated hearing tests.

Objective: This study evaluated the agreement of self-administered tests with clinician-administered tests in detecting hearing loss and speech-in-noise deficits in Aboriginal & Torres Strait Islander children.Design: Children completed clinician-administered audiometry, self-administered automatic audiometry (AutoAud), clinician-administered Listening in Spatialised Noise - Sentences test and self-administered tablet-based hearing game Sound Scouts. Comparisons were made between tests to determine the agreement of the self-administered tests with clinician-administered tests in detecting hearing loss and speech-in-noise deficits.Study sample: Two hundred and ninety seven Aboriginal and Torres Strait Islander children aged 4-14 years from three schools.Results: Acceptable threshold differences of ≤5 dB between AutoAud and manual audiometry hearing thresholds were found for 88% of thresholds, with a greater agreement for older than for younger children. Consistent pass/fail results on the Sound Scouts speech-in-quiet measure and manual audiometry were found for 81% of children. Consistent pass/fail results on the Sound Scouts speech-in-noise measure and LiSN-S high-cue condition were found for 73% of children.Conclusions: This study shows good potential in using self-administered applications as initial tests for hearing problems in children. These tools may be especially valuable for children in remote locations and those from low socio-economic backgrounds who may not have easy access to healthcare.

The development of the listening in spatialised noise - universal test (LiSN-U) and preliminary evaluation in English-speaking listeners.

Objective: To create a language independent version of the Listening in Spatialised Noise - Sentences test (LiSN-S) and evaluate it in an English-speaking population.Design: Test development and normative data collection. LiSN-Universal (LiSN-U) targets consisted of CVCV pseudo-words (e.g. /mupa/). Two looped distracter tracks consisted of CVCVCVCV pseudo-words. The listener's task was to repeat back the target pseudo-words. Stimuli were presented over headphones using an iPad. Speech reception thresholds were measured adaptively. In the co-located condition all stimuli came from directly in front. In the spatially-separated condition the distracters emanated from +90° and -90° azimuth. Perceived location was manipulated using head-related transfer functions. Spatial advantage was calculated as the difference in dB between the co-located and spatially separated conditions.Study samples: Stimulus intelligibility data were collected from 20 adults. Normative data were collected from native English speakers (23 adults and 127 children).Results: Children's spatially separated, co-located, and spatial advantage results improved significantly with age. Spatial advantage was 4-6 dB larger in the LiSN-U than LiSN-S depending on age group.Conclusion: Whereas additional research in non-native English populations is required, the LiSN-U appears to be an effective tool for measuring spatial processing ability.

Development, validity, reliability and normative data of the Persian Phonemic Synthesis Test (P-PST).

Objectives: This study was conducted to develop the Persian version of the Phonemic Synthesis Test, evaluate its psychometric properties and generate normative data.Design: Test development, including the optimisation of materials, determining content and face validities and assessing the psychometric properties.Study samples: Overall, 425 subjects participated in this study in three different stages. Ten experts participated in the content validity assessment stage. The face validity was determined by taking the views of 17 subjects, including children diagnosed with APD, normal children and experts. The psychometric properties were evaluated with 395 normal children aged 7 to 11, divided into five age groups. All the participants were retested after four weeks for evaluating the test-retest reliability.Results: The results revealed the strong content and face validity of the test. No significant differences were observed between the genders. Significant differences were observed in the quantitative and qualitative scores among the age groups. The Spearman correlation coefficient showed that the scores of the test and retest were strongly and positively correlated (r > 0.9). The findings showed many similarities with the data reported in the original American English Phonemic Synthesis Test.Conclusions: The Persian Phonemic Synthesis Test is a reliable and valid test for auditory processing assessments in Persian-speaking children.

Transcranial Static Magnetic Field Stimulation Over the Temporal Cortex Modulating the Right Ear Advantage in Dichotic Listening.

OBJECTIVE: Transcranial static magnetic field stimulation (tSMS) has proposed a new, promising, and simple non-invasive brain stimulation method. While several studies gained certain evidence about tSMS effects in the motor, somatosensory, and visual domains, there is still a controversial debate about its general effectiveness. In the present study, we investigated potential tSMS effects on auditory speech processing as measured by a dichotic listening (DL) task. MATERIALS AND METHODS: Fifteen healthy participants received in randomized order on three different days one session of either sham, tSMS over the left, or tSMS over the right auditory cortex (AC). Under stimulation, participants performed a standard DL task with consonant-vowel syllables. Simultaneously, we recorded electroencephalogram from central sites (Fz, Cz, Pz). RESULTS: TSMS over the left AC changed the behavioral performance and modulated auditory evoked potentials. Stimulation of the left AC significantly reduced the right ear advantage during the DL task and the N1 component of auditory evoked potentials in response to these syllables. CONCLUSIONS: The preliminary results of the present exploratory study demonstrate the ability of tSMS to modulate human brain activity on a behavioral as well as physiologic level. Furthermore, tSMS effects on acoustic processing may have clinical implications by fostering potential approaches for a treatment of speech-related pathologies associated with hyperexcitability in the AC.

Estimates of functional cerebral hemispheric differences in monolingual and bilingual people who stutter: dichotic listening paradigm.

Recent studies indicate functional cerebral hemispheric processing differences between monolinguals and bilinguals who stutter, as well as monolinguals and bilinguals who do not stutter. Eighty native German speakers, half of whom were also proficient speakers of English as a second language (L2), were assessed on a dichotic listening paradigm using CV syllables as stimuli. The participants were organised into four different groups according to speech status and language ability: 20 monolinguals who stutter, 20 bilinguals who stutter, 20 monolinguals who do not stutter, and 20 bilinguals who do not stutter. A right ear advantage (REA) was observed across all groups with no significant group differences in regard to hemispheric asymmetry. Although MWS (18 dB) and BWS (16 dB) crossed over to an LEA at an earlier point compared to the MWNS (5 dB) and BWNS (2 dB), the difference between groups was minor and not significant. Thus, a significant difference in REA resistance, as proposed by other researchers, was not reflected in the current study neither for people who stutter nor for bilinguals. In addition, no meaningful relationship was found between dichotic listening and stuttering severity, as well as the four language modalities (listening, speaking, reading, writing). Thus, we contend that neither stuttering nor bilingualism has any non-trivial effect on functional cerebral hemispheric differences in language processing in dichotic listening.

Attention Is Required for Knowledge-Based Sequential Grouping: Insights from the Integration of Syllables into Words.

How the brain groups sequential sensory events into chunks is a fundamental question in cognitive neuroscience. This study investigates whether top-down attention or specific tasks are required for the brain to apply lexical knowledge to group syllables into words. Neural responses tracking the syllabic and word rhythms of a rhythmic speech sequence were concurrently monitored using electroencephalography (EEG). The participants performed different tasks, attending to either the rhythmic speech sequence or a distractor, which was another speech stream or a nonlinguistic auditory/visual stimulus. Attention to speech, but not a lexical-meaning-related task, was required for reliable neural tracking of words, even when the distractor was a nonlinguistic stimulus presented cross-modally. Neural tracking of syllables, however, was reliably observed in all tested conditions. These results strongly suggest that neural encoding of individual auditory events (i.e., syllables) is automatic, while knowledge-based construction of temporal chunks (i.e., words) crucially relies on top-down attention.SIGNIFICANCE STATEMENT Why we cannot understand speech when not paying attention is an old question in psychology and cognitive neuroscience. Speech processing is a complex process that involves multiple stages, e.g., hearing and analyzing the speech sound, recognizing words, and combining words into phrases and sentences. The current study investigates which speech-processing stage is blocked when we do not listen carefully. We show that the brain can reliably encode syllables, basic units of speech sounds, even when we do not pay attention. Nevertheless, when distracted, the brain cannot group syllables into multisyllabic words, which are basic units for speech meaning. Therefore, the process of converting speech sound into meaning crucially relies on attention.

Diminished pre-stimulus alpha-lateralization suggests compromised self-initiated attentional control of auditory processing in old age.

Older adults experience difficulties in daily situations that require flexible information selection in the presence of multiple competing sensory inputs, like for instance multi-talker situations. Modulations of rhythmic neural activity in the alpha-beta (8-30 Hz) frequency range in posterior brain areas have been established as a cross-modal neural correlate of selective attention. However, research linking compromised auditory selective attention to changes in rhythmic neural activity in aging is sparse. We tested younger (n = 25; 22-35 years) and older adults (n = 26; 63-76 years) in an attention modulated dichotic listening task. In this, two streams of highly similar auditory input were simultaneously presented to participants' both ears (i.e., dichotically) while attention had to be focused on the input to only one ear (i.e. target) and the other, distracting information had to be ignored. We here demonstrate a link between severely compromised auditory selective attention in aging and a partial reorganization of attention-related rhythmic neural responses. In particular, in old age we observed a shift from a self-initiated, preparatory modulation of lateralized alpha rhythmic activity to an externally driven response in the alpha-beta range. Critically, moment-to-moment fluctuations in the age-specific patterns of self-initiated and externally driven lateralized rhythmic activity were associated with behavioral performance. We conclude that adult age differences in spatial selective attention likely derive from a functional reorganization of rhythmic neural activity within the aging brain.