Hemispheric asymmetries for music and speech: Spectrotemporal modulations and top-down influences

Unraveling eye movement-related eardrum oscillations (EMREOs): how saccade direction and tympanometric measurements relate to their amplitude and time course

Eye movement-related eardrum oscillations (EMREOs) reflect movements of the tympanic membrane that scale with the magnitude and direction of saccades. EMREOs have been consistently described in humans and non-human primates, yet many questions regarding this phenomenon remain unresolved. Based on bilateral in-ear recordings in human participants we here explore several properties of these EMREOs in order to improve our understanding of this signal's origin and functional significance. Our data support that the EMREO time course is comparable between the left and right ears, and between paradigms guiding saccades by visual and auditory target stimuli. However, the precise amplitude time course differs significantly between ipsi- and contralateral saccades in addition to the previously known phase-inversion described for saccades in opposing directions. Finally, our data suggest that the EMREO amplitude is negatively related to the compliance of the tympanic membrane as established by tympanometry. Collectively, these results support the notion that EMREOs reflect motor-related top-down signals relayed to the ear from yet-to-be-resolved sources, and fuel the speculation that EMREOs may be generated by the middle ear muscles in a differential operation similar to the execution of ipsi- and contralateral saccades.

"What" and "When" Predictions Jointly Modulate Speech Processing

Adaptive behavior rests on predictions based on statistical regularities in the environment. Such regularities pertain to stimulus contents ("what") and timing ("when"), and both interactively modulate sensory processing. In speech streams, predictions can be formed at multiple hierarchical levels of contents (e.g., syllables vs words) and timing (faster vs slower time scales). Whether and how these hierarchies map onto each other remains unknown. Under one hypothesis, neural hierarchies may link "what" and "when" predictions within sensory processing areas: with lower versus higher cortical regions mediating interactions for smaller versus larger units (syllables vs words). Alternatively, interactions between "what" and "when" regularities might rest on a generic, sensory-independent mechanism. To address these questions, we manipulated "what" and "when" regularities at two levels-single syllables and disyllabic pseudowords-while recording neural activity using magnetoencephalography (MEG) in healthy volunteers (N = 22). We studied how neural responses to syllable and/or pseudoword deviants are modulated by "when" regularity. "When" regularity modulated "what" mismatch responses with hierarchical specificity, such that responses to deviant pseudowords (vs syllables) were amplified by temporal regularity at slower (vs faster) time scales. However, both these interactive effects were source-localized to the same regions, including frontal and parietal cortices. Effective connectivity analysis showed that the integration of "what" and "when" regularity selectively modulated connectivity within regions, consistent with gain effects. This suggests that the brain integrates "what" and "when" predictions that are congruent with respect to their hierarchical level, but this integration is mediated by a shared and distributed cortical network.

Proprioceptive Resonance and Multimodal Semiotics: Readiness to Act, Embodied Cognition, and the Dynamics of Meaning

This paper proposes a theoretical model of meaning-making grounded in proprioceptive awareness and embodied imagination, arguing that human cognition is inherently multimodal, anticipatory, and sensorimotor. Drawing on Peircean semiotics, Lotman's model of cultural cognition, and current research in neuroscience, we show that readiness to act-a proprioceptively grounded anticipation of movement-plays a fundamental role in the emergence of meaning, from perception to symbolic abstraction. Contrary to traditional approaches that reduce language to a purely symbolic or visual system, we argue that meaning arises through the integration of sensory, motor, and affective processes, structured by axial proprioceptive coordinates (vertical, horizontal, sagittal). Using Peirce's triadic model of interpretants, we identify proprioception as the modulatory interface between sensory stimuli, emotional response, and logical reasoning. A study on skilled pianists supports this view, showing that mental rehearsal without physical execution improves performance via motor anticipation. We define this process as proprioceptive resonance, a dynamic synchronization of embodied states that enables communication, language acquisition, and social intelligence. This framework allows for a critique of linguistic abstraction and contributes to ongoing debates in semiotics, enactive cognition, and the origin of syntax, challenging the assumption that symbolic thought precedes embodied experience.

Predictive coding and dimension-selective attention enhance the lateralization of spoken language processing

Hemispheric lateralization in speech and language processing exemplifies functional brain specialization. Seminal work in patients with left hemisphere damage highlighted the left-hemispheric dominance in language functions. However, speech processing is not confined to the left hemisphere. Hence, some researchers associate lateralization with auditory processing asymmetries: slow temporal and fine spectral acoustic information is preferentially processed in right auditory regions, while faster temporal information is primarily handled by left auditory regions. Other scholars posit that lateralization relates more to linguistic processing, particularly for speech and speech-like stimuli. We argue that these seemingly distinct accounts are interdependent. Linguistic analysis of speech relies on top-down processes, such as predictive coding and dimension-selective auditory attention, which enhance lateralized processing by engaging left-lateralized sensorimotor networks. Our review highlights that lateralization is weaker for simple sounds, stronger for speech-like sounds, and strongest for meaningful speech. Evidence shows that predictive speech processing and selective attention enhance lateralization. We illustrate that these top-down processes rely on left-lateralized sensorimotor networks and provide insights into the role of these networks in speech processing.

Cortical and behavioral tracking of rhythm in music: Effects of pitch predictability, enjoyment, and expertise

The cortical tracking of stimulus features is a crucial neural requisite of how we process continuous music. We here tested whether cortical tracking of the beat, typically related to rhythm processing, is modulated by pitch predictability and other top-down factors. Participants listened to tonal (high pitch predictability) and atonal (low pitch predictability) music while undergoing electroencephalography. We analyzed their cortical tracking of the acoustic envelope. Cortical envelope tracking was stronger while listening to atonal music, potentially reflecting listeners' violated pitch expectations and increased attention allocation. Envelope tracking was also stronger with more expertise and enjoyment. Furthermore, we showed cortical tracking of pitch surprisal (using IDyOM), which suggests that listeners' expectations match those computed by the IDyOM model, with higher surprisal for atonal music. Behaviorally, we measured participants' ability to finger-tap to the beat of tonal and atonal sequences in two experiments. Finger-tapping performance was better in the tonal condition, indicating a positive effect of pitch predictability on behavioral rhythm processing. Cortical envelope tracking predicted tapping performance for tonal music, as did pitch-surprisal tracking for atonal music, indicating that high and low predictability might impose different processing regimes. Taken together, our results show various ways that top-down factors impact musical rhythm processing.

The role of musical aspects of language in human cognition

This paper reviews musicology, linguistics, cognitive psychology, and neuroscience research on the importance of music in developing human speech and cognition. It cites research from several scientific fields on how the brain processes and reacts to melody, rhythm, harmony, loudness, dynamics and types of articulation and timbre. It also discusses musical concepts and prosodic features such as intonation, rhythm and stress related to linguistic terminology and summarises results of earlier research on how the two systems interact to strengthen or weaken an individual's ability to function without nurturing stimulation. Music is an important preventive and therapeutic factor for human life. The author describes the interplay between music and language in the nervous system, improving or hindering communication and how it affects us personally and impacts societal mental health.

Dynamics of Pitch Perception in the Auditory Cortex

The ability to perceive pitch allows human listeners to experience music, recognize the identity and emotion conveyed by conversational partners, and make sense of their auditory environment. A pitch percept is formed by weighting different acoustic cues (e.g., signal fundamental frequency and interharmonic spacing) and contextual cues (expectation). How and when such cues are neurally encoded and integrated remains debated. In this study, 28 participants (16 female) listened to tone sequences with different acoustic cues (pure tones, complex missing fundamental tones, and tones with an ambiguous mixture), placed in predictable and less predictable sequences, while magnetoencephalography was recorded. Decoding analyses revealed that pitch was encoded in neural responses to all three tone types in the low-to-mid auditory cortex and sensorimotor cortex bilaterally, with right-hemisphere dominance. The pattern of activity generalized across cue types, offset in time: pitch was neurally encoded earlier for harmonic tones (∼85 ms) than pure tones (∼95 ms). For ambiguous tones, pitch emerged significantly earlier in predictable contexts than in unpredictable. The results suggest that a unified neural representation of pitch emerges by integrating independent pitch cues and that context alters the dynamics of pitch generation when acoustic cues are ambiguous.

Acoustic Exaggeration Enhances Speech Discrimination in Young Autistic Children

Child-directed speech (CDS), which amplifies acoustic and social features of speech during interactions with young children, promotes typical phonetic and language development. In autism, both behavioral and brain data indicate reduced sensitivity to human speech, which predicts absent, decreased, or atypical benefits of exaggerated speech signals such as CDS. This study investigates the impact of exaggerated fundamental frequency (F0) and voice-onset time on the neural processing of speech sounds in 22 Chinese-speaking autistic children aged 2-7 years old with a history of speech delays, compared with 25 typically developing (TD) peers. Electroencephalography (EEG) data were collected during passive listening to exaggerated and non-exaggerated syllables. A time-resolved multivariate pattern analysis (MVPA) was used to evaluate the potential effects of acoustic exaggeration on syllable discrimination in terms of neural decoding accuracy. For non-exaggerated syllables, neither the autism nor the TD group achieved above-chance decoding accuracy. In contrast, for exaggerated syllables, both groups achieved above-chance decoding, indicating significant syllable discrimination, with no difference in accuracy between the autism and TD groups. However, the temporal generalization patterns in the MVPA results revealed distinct neural mechanisms supporting syllable discrimination between the groups. Although the TD group demonstrated a left-hemisphere advantage for decoding and generalization, the autism group displayed similar decoding patterns between hemispheres. These findings highlight the potential of selective acoustic exaggeration to support speech learning in autistic children, underscoring the importance of tailored, sensory-based interventions.

Response strength and latencies of auditory steady-state responses from age six

OBJECTIVE

Auditory-steady state responses (ASSRs) to stimuli modulated by different frequencies may differ between children and adults. These differences in response characteristics or latency may reflect developmental changes. This study investigates age-related differences in response strength, latencies, and hemispheric laterality indices of ASSRs for different modulation frequencies.

DESIGN

Multi-channel EEG was used to measure ASSRs to broadband noise, modulated at either 40 or 80 Hz, presented at 70 dB SPL to the left, right, or both ears.

STUDY SAMPLE

This study involved 18 adults (20-26 years) and 17 children divided into two age groups: younger children (6-10 years) and older children (11-14 years).

RESULTS

Advancing age was associated with increased response strength and prolonged latencies for 40-Hz ASSRs, with significant differences observed between adults and younger children. No significant age-related differences were noted for 80-Hz ASSRs. Laterality analysis indicated a right-hemisphere tendency for 40-Hz ASSRs in older children and 80-Hz ASSRs in younger children, respectively.

CONCLUSION

The study indicates the development of 40-Hz ASSRs with increasing response strength and prolonged latencies. The results of children with normal hearing are important for further research on children with hearing impairment.

The arts and hemispheric specialization

Art was initially thought of as a single function linked mainly to spatial perception and right hemisphere functional specialization. Art was also considered to be diametrically opposed to language, further solidifying the right hemisphere specialization model. This view remained dominant for many decades. However, increase in published observations of artworks by professional artists following acquired unilateral hemispheric damage showed that quality artistic works can be produced when there is damage in either the left or the right hemisphere. With the advent of neuroimaging such as functional magnetic resonance imaging (fMRI), light was shed on the neural underpinning of the esthetics of artworks revealing activation in multiple regions across both hemispheres. The bulk of recent data suggests complementary hemispheric contributions to art production and esthetic evaluation of numerous art expressions. Similarly, creativity and imagination, upon which art expression depends, both appear to recruit interhemispheric processes. Culturally, the early evolutionary origin of art is associated mainly with Homo sapiens (HS) but, despite evidence for cerebral asymmetry based on fossil skulls, their emergence did not coincide with visual art making. A significant lag of hundreds of thousands of years intervened before humans produced art consistently and abundantly. By now, the arts are practiced ubiquitously throughout the globe, in all human societies.

Handedness

This chapter offers an overview of the literature on human handedness and its assessment in clinical neurologic practice and research. There are two major forms of handedness: hand preference, which describes a subjective preference to use one hand over the other for skilled motor activities like writing, and hand skill, which describes objectively measured mother skill. This chapter gives an overview of widely used questionnaires and tests to assess hand preference and hand skill, as well as suggestions on how to determine handedness categories such as left-handed, right-handed, and mixed-handed based on the results of these questionnaires and tests. Handedness is just one form of hemispheric asymmetry in the human motor system, and the chapter also provides an overview of its association with other motor asymmetries such as footedness. Moreover, the associations of handedness with functional brain activation as well as with structural markers on the cortical, subcortical, cerebellar, and spinal levels are discussed. Furthermore, the potential relevance of handedness retraining for clinical neurologic research and the association of handedness and cognitive abilities are discussed. The chapter concludes with an outlook on the critical importance of including handedness in clinical neurologic research and practice.

Hemispheric Asymmetry of Intracortical Myelin Orientation in the Mouse Auditory Cortex

Communication sound processing in mouse AC is lateralized. Both left and right AC are highly specialised and differ in auditory stimulus representation, functional connectivity and field topography. Previous studies have highlighted intracortical functional circuits that explain hemispheric stimulus preference. However, the underlying microstructure remains poorly understood. In this study, we examine structural lateralization of AC on the basis of immunohistochemically stained and tissue-cleared adult mouse brains (n = 11). We found hemispheric asymmetries of intracortical myelination, most prominently in layer 2/3, which featured more intercolumnar connections in the right AC. Furthermore, we found a larger structural asymmetry in the right AC. We also investigated sex differences. In male mice, myelination direction in the right AC is tilted to the anterior side. This pattern is inverted in female mice. However, the spatial distribution of neuronal cell bodies in the left and right AC along the laminar axis of the cortex was remarkably symmetric in all samples. These results suggest that basic developmentally defined structures such as cortical columns remain untouched by lateral specialisation, but more plastic myelinated axons show diverse hemispheric asymmetries. These asymmetries may contribute to specialisation on lateralized tasks such as vocal communication processing or specialisation on spectral or temporal complexity of stimuli.

Temporal and Fronto-Central Auditory Evoked Responses in Children with Neurodevelopmental Disorders: A Scoping Review

At the cortical level, the central auditory neural system (CANS) includes primary and secondary areas. So far, much research has focused on recording fronto-central auditory evoked potentials/responses (P1-N1-P2), originating mainly from the primary auditory areas, to explore the neural processing in the auditory cortex. However, less is known about the secondary auditory areas. This review aimed to investigate and compare fronto-central and T-complex responses in populations at risk of auditory dysfunction, such as individuals with neurodevelopmental disorders. After searching the electronic databases (PubMed, Web of Science, Scopus, and Ovid), ten studies encompassing six neurodevelopmental disorders were included for the analysis. All experimental populations had atypical T-complexes, manifesting as an absence of evoked responses, shorter latency, and/or smaller amplitude. Moreover, in two experimental groups, dyslexia and attention deficit/hyperactivity disorder (ADHD), abnormal T-complex responses were observed despite the presence of normal fronto-central responses. The presence of abnormal T-complex responses in combination with normal fronto-central responses in the same population, using the same experiment, may highlight the advantage of the T-complex for indexing deficits in distinct auditory processes or regions, which the fronto-central response may not track.

Heschl's gyrus and the temporal pole: The cortical lateralization of language

The left lateralization of language has been attributed to hemispheric specialization for processing rapidly changing information. While interhemispheric differences in auditory cortex organization support this view, the macrostructure of the entire cerebral cortex has not been thoroughly examined from this perspective. This study investigated hemispheric asymmetries in cortical surface area and thickness and their relationship to pronunciation scores from oral reading using the Human Connectome Project Young Adult dataset (N=1113). Heschl's gyrus had the most left-lateralized surface area, while the temporal pole showed the strongest right-lateralization in thickness. These areas correspond to the core components of speech: sound and meaning. Notably, their structural features were the only ones also yielding a significant correlation with pronunciation scores. Additionally, Broca's area's posterior region (pars opercularis), involved in articulatory phonological processing, showed leftward lateralization, contrasting with the right-lateralized anterior portions. Left-hemisphere language areas were largely thinner and more extended than their right-sided homologs with a larger white-to-gray matter ratio. Cortical thickness was inversely related to surface area. The lateralization of auditory-related language areas and their structure's correlation with pronunciation in oral reading supports a genetically based auditory foundation for language. A thinner, more efficient cortex with larger surface areas and increased myelination likely underlies the left-hemispheric dominance of language. Thinner, more extended brain areas have been linked to more myelination and wider cortical columns and intercolumnar space. This provides the potential for a fast network of interconnected, discrete information units able to support language's demands of rapid categorical processing.

Insights into epileptic aphasia: Intracranial recordings in a child with a left insular ganglioglioma

Intracranial EEG was recorded during a dialog-based task in a 16-year-old boy with a left insular ganglioglioma, medically intractable epilepsy, epileptic foci in auditory cortex on the lateral superior temporal gyrus (STG) and language deficiencies. Performance of the task was highly erratic, characterized by rapid cycling between providing correct answers, incorrect answers and failure to respond. There was no relationship between performance and the degree of concurrent epileptic activity in auditory cortex. High gamma activity in core auditory cortex (posterior medial Heschl's gyrus, HGPM) was markedly diminished during listening and, with two exceptions, was less than activity from 17 control subjects. The two exceptions also had seizure onset zones in perisylvian cortex. Responses during listening were of smaller amplitude than those occurring during speaking, a pattern opposite that typically seen in the left HGPM. Within HGPM, lateral STG and pars opercularis of the inferior frontal gyrus, high gamma activity while listening was greatest when questions were correctly answered and least when the subject failed to respond. Alpha activity preceding utterances was lowest in pars opercularis when the subject failed to respond. Comparisons between resting state activity in another cohort of controls and the subject were most disparate in HGPM. Alpha activity during performance of the task was greatest in the mid-anterior cingulate when the subject failed to respond, suggesting dysfunction beyond the speech network and into the salience network. Multiple abnormalities noted in this patient paralleled those seen in epileptic aphasia and Rolandic epilepsy.

Musical Sophistication and Multilingualism: Effects on Arcuate Fasciculus Characteristics

The processing of auditory stimuli which are structured in time is thought to involve the arcuate fasciculus, the white matter tract which connects the temporal cortex and the inferior frontal gyrus. Research has indicated effects of both musical and language experience on the structural characteristics of the arcuate fasciculus. Here, we investigated in a sample of n = 84 young adults whether continuous conceptualizations of musical and multilingual experience related to structural characteristics of the arcuate fasciculus, measured using diffusion tensor imaging. Probabilistic tractography was used to identify the dorsal and ventral parts of the white matter tract. Linear regressions indicated that different aspects of musical sophistication related to the arcuate fasciculus' volume (emotional engagement with music), volumetric asymmetry (musical training and music perceptual abilities), and fractional anisotropy (music perceptual abilities). Our conceptualization of multilingual experience, accounting for participants' proficiency in reading, writing, understanding, and speaking different languages, was not related to the structural characteristics of the arcuate fasciculus. We discuss our results in the context of other research on hemispheric specializations and a dual-stream model of auditory processing.

Musicianship and Prominence of Interhemispheric Connectivity Determine Two Different Pathways to Atypical Language Dominance

During infancy and adolescence, language develops from a predominantly interhemispheric control-through the corpus callosum (CC)-to a predominantly intrahemispheric control, mainly subserved by the left arcuate fasciculus (AF). Using multimodal neuroimaging, we demonstrate that human left-handers (both male and female) with an atypical language lateralization show a rightward participation of language areas from the auditory cortex to the inferior frontal cortex when contrasting speech to tone perception and an enhanced interhemispheric anatomical and functional connectivity. Crucially, musicianship determines two different structural pathways to this outcome. Nonmusicians present a relation between atypical lateralization and intrahemispheric underdevelopment across the anterior AF, hinting at a dysregulation of the ontogenetic shift from an interhemispheric to an intrahemispheric brain. Musicians reveal an alternative pathway related to interhemispheric overdevelopment across the posterior CC and the auditory cortex. We discuss the heterogeneity in reaching atypical language lateralization and the relevance of early musical training in altering the normal development of language cognitive functions.

Age-related neural changes underlying long-term recognition of musical sequences

Aging is often associated with decline in brain processing power and neural predictive capabilities. To challenge this notion, we used magnetoencephalography (MEG) and magnetic resonance imaging (MRI) to record the whole-brain activity of 39 older adults (over 60 years old) and 37 young adults (aged 18-25 years) during recognition of previously memorised and varied musical sequences. Results reveal that when recognising memorised sequences, the brain of older compared to young adults reshapes its functional organisation. In fact, it shows increased early activity in sensory regions such as the left auditory cortex (100 ms and 250 ms after each note), and only moderate decreased activity (350 ms) in medial temporal lobe and prefrontal regions. When processing the varied sequences, older adults show a marked reduction of the fast-scale functionality (250 ms after each note) of higher-order brain regions including hippocampus, ventromedial prefrontal and inferior temporal cortices, while no differences are observed in the auditory cortex. Accordingly, young outperform older adults in the recognition of novel sequences, while no behavioural differences are observed with regards to memorised ones. Our findings show age-related neural changes in predictive and memory processes, integrating existing theories on compensatory neural mechanisms in non-pathological aging.

Auditory perceptual ability affects dichotic listening performance in older adults

Age-related changes pose challenges in speech processing for older adults. However, little is known about the role of auditory perceptual ability in their performance in dichotic listening tasks. The present study investigated how older adults' auditory perceptual abilities affected their correct rates and the right ear advantage (REA) in the dichotic listening tasks in two experiments. In Experiment 1, older adults' performance was assessed using dichotic listening tasks based on consonant-vowel (CV) words varying in consonants, vowels, and lexical tones, each presenting distinct auditory perceptual demands. It was found that older adults exhibited decreased correct rates as auditory perceptual demands increased. Moreover, differences in the REA were observed in older listeners, suggesting increased engagement of the hemisphere responsible for acoustic analysis in processing challenging dichotic stimuli. Experiment 2 examined how older individuals' acoustic processing abilities contributed to their dichotic listening performance. It was shown that older adults with acoustic processing abilities comparable to those of younger individuals demonstrated correct rates and REAs similar to those of younger cohorts. These results revealed the nonnegligible role of acoustic processing in the dichotic listening paradigm and the significance of considering listeners' auditory perceptual abilities in investigating language lateralisation using the dichotic listening paradigm.

Phenotypic analysis of multielectrode array EEG biomarkers in developing and adult male Fmr1 KO mice

Fragile X Syndrome (FXS) is a leading known genetic cause of intellectual disability with symptoms that include increased anxiety and social and sensory processing deficits. Recent electroencephalographic (EEG) studies in humans with FXS have identified neural oscillation deficits that include increased resting state gamma power, increased amplitude of auditory evoked potentials, and reduced phase locking of sound-evoked gamma oscillations. Similar EEG phenotypes are present in mouse models of FXS, but very little is known about the development of such abnormal responses. In the current study, we employed a 30-channel mouse multielectrode array (MEA) system to record and analyze resting and stimulus-evoked EEG signals in male P21 and P91 WT and Fmr1 KO mice. This led to several novel findings. First, P91, but not P21, Fmr1 KO mice have significantly increased resting EEG power in the low- and high-gamma frequency bands. Second, both P21 and P91 Fmr1 KO mice have markedly attenuated inter-trial phase coherence (ITPC) to spectrotemporally dynamic auditory stimuli as well as to 40 Hz and 80 Hz auditory steady-state response (ASSR) stimuli. This suggests abnormal temporal processing from early development that may lead to abnormal speech and language function in FXS. Third, we found hemispheric asymmetry of fast temporal processing in the mouse auditory cortex in WT but not Fmr1 KO mice. Together, these findings define a set of EEG phenotypes in young and adult mice that can serve as translational targets for genetic and pharmacological manipulation in phenotypic rescue studies.

Rapid auditory and phonemic processing relies on the left planum temporale

After initial bilateral acoustic processing of the speech signal, much of the subsequent language processing is left-lateralized. The reason for this lateralization remains an open question. Prevailing hypotheses describe a left hemisphere (LH) advantage for rapidly unfolding information-such as the segmental (e.g., phonetic and phonemic) components of speech. Here we investigated whether and where damage to the LH predicted impaired performance on judging the directionality of frequency modulated (FM) sweep stimuli that changed within short (25ms) or longer (250ms) temporal windows. Performance was significantly lower for stroke survivors (n = 50; 18 female) than controls (n = 61; 34 female) on FM Sweeps judgments, particularly on the short sweeps. Support vector regression lesion-symptom mapping (SVR-LSM) revealed that part of the left planum temporale (PT) was related to worse performance on judging the short FM sweeps, controlling for performance on the long sweeps. We then investigated whether damage to this particular area related to diminished performance on two levels of linguistic processing that theoretically depend on rapid auditory processing: stop consonant identification and pseudoword repetition. We separated stroke participants into subgroups based on whether their LH lesion included the part of the left PT that related to diminished short sweeps judgments. Participants with PT lesions (PT lesion+, n = 24) performed significantly worse than those without (PT lesion-, n = 26) on stop consonant identification and pseudoword repetition, controlling for lesion size and hearing ability. Interestingly, PT lesions impacted pseudoword repetition more than real word repetition (PT lesion-by-repetition trial type interaction), which is of interest because pseudowords rely solely on sound perception and sequencing, whereas words can also rely on lexical-semantic knowledge. We conclude that the left PT is a critical region for processing auditory information in short temporal windows, and it may also be an essential transfer point in auditory-to-linguistic processing.

Spectrotemporal cues and attention jointly modulate fMRI network topology for sentence and melody perception

Speech and music are two fundamental modes of human communication. Lateralisation of key processes underlying their perception has been related both to the distinct sensitivity to low-level spectrotemporal acoustic features and to top-down attention. However, the interplay between bottom-up and top-down processes needs to be clarified. In the present study, we investigated the contribution of acoustics and attention to melodies or sentences to lateralisation in fMRI functional network topology. We used sung speech stimuli selectively filtered in temporal or spectral modulation domains with crossed and balanced verbal and melodic content. Perception of speech decreased with degradation of temporal information, whereas perception of melodies decreased with spectral degradation. Applying graph theoretical metrics on fMRI connectivity matrices, we found that local clustering, reflecting functional specialisation, linearly increased when spectral or temporal cues crucial for the task goal were incrementally degraded. These effects occurred in a bilateral fronto-temporo-parietal network for processing temporally degraded sentences and in right auditory regions for processing spectrally degraded melodies. In contrast, global topology remained stable across conditions. These findings suggest that lateralisation for speech and music partially depends on an interplay of acoustic cues and task goals under increased attentional demands.

Analysis of Loudness Discomfort Level Tests in Tinnitus Patients

INTRODUCTION

We aimed to investigate the clinical significance of the loudness discomfort level (LDL) test in tinnitus patients and its relationship with pure-tone audiometry, tinnitogram, and questionnaires.

METHODS

We retrospectively reviewed the medical records of 320 tinnitus patients who visited a tertiary university hospital's tinnitus clinic and completed LDL tests between March 2020 and December 2022. Epidemiological data and psychoacoustic test results were collected.

RESULTS

The LDL showed no significant differences between frequencies for both ears. The mean LDL did not correlate with mean pure-tone average or hearing thresholds at each frequency. The hearing loss group had a higher LDL at 8 kHz compared to the normal hearing group (p < 0.01). Objective sound intolerance was found in a quarter, correlating with subjective hyperacusis, anxiety, and depression. Weak negative correlations were found between most of questionnaire's scores and LDL on the left side. Tinnitus loudness weak negatively correlated with LDL at most frequencies, except 8 kHz.

DISCUSSION/CONCLUSION

Our findings suggest a notable association between LDL levels and emotional factors in tinnitus patients, rather than with auditory thresholds. While lateralized differences in LDL responses were observed, specifically on the left side, these preliminary results do not confirm a causal link and thus do not warrant changes to current clinical testing protocols without further research.