Investigating the different mechanisms in related neural activities: a focus on auditory perception and imagery.

Neuroimaging studies have shown that the neural representation of imagery is closely related to the perception modality; however, the undeniable different experiences between perception and imagery indicate that there are obvious neural mechanism differences between them, which cannot be explained by the simple theory that imagery is a form of weak perception. Considering the importance of functional integration of brain regions in neural activities, we conducted correlation analysis of neural activity in brain regions jointly activated by auditory imagery and perception, and then brain functional connectivity (FC) networks were obtained with a consistent structure. However, the connection values between the areas in the superior temporal gyrus and the right precentral cortex were significantly higher in auditory perception than in the imagery modality. In addition, the modality decoding based on FC patterns showed that the FC network of auditory imagery and perception can be significantly distinguishable. Subsequently, voxel-level FC analysis further verified the distribution regions of voxels with significant connectivity differences between the 2 modalities. This study complemented the correlation and difference between auditory imagery and perception in terms of brain information interaction, and it provided a new perspective for investigating the neural mechanisms of different modal information representations.

A Longitudinal Framework to Describe the Relation Between Age-Related Hearing Loss and Social Isolation.

Many older adults live with some form of hearing loss and have difficulty understanding speech in the presence of background sound. Experiences resulting from such difficulties include increased listening effort and fatigue. Social interactions may become less appealing in the context of such experiences, and age-related hearing loss is associated with an increased risk of social isolation and associated negative psychosocial health outcomes. However, the precise relationship between age-related hearing loss and social isolation is not well described. Here, we review the literature and synthesize existing work from different domains to propose a framework with three conceptual anchor stages to describe the relation between hearing loss and social isolation: within-situation disengagement from listening, social withdrawal, and social isolation. We describe the distinct characteristics of each stage and suggest potential interventions to mitigate negative impacts of hearing loss on social lives and health. We close by outlining potential implications for researchers and clinicians.

Determining Hearing Thresholds in Dogs Using the Staircase Method.

There is a growing interest in performing playback experiments to understand which acoustical cues trigger specific behavioral/emotional responses in dogs. However, very limited studies have focused their attention on more basic aspects of hearing such as sensitivity, i.e., the identification of minimal intensity thresholds across different frequencies. Most previous studies relied on electrophysiological methods for audiograms for dogs, but these methods are considered less accurate than assessments based on behavioral responses. To our knowledge, only one study has established hearing thresholds using a behavioral assessment on four dogs but using a method that did not allow potential improvement throughout the sessions. In the present study, we devised an assessment procedure based on a staircase method. Implying the adaptation of the assessed intensity on the dogs' performance, this approach grants several assessments around the actual hearing threshold of the animal, thereby increasing the reliability of the result. We used such a method to determine hearing thresholds at three frequencies (0.5, 4.0, and 20.0 kHz). Five dogs were tested in each frequency. The hearing thresholds were found to be 19.5 ± 2.8 dB SPL at 0.5 kHz, 14.0 ± 4.5 dB SPL at 4.0 kHz, and 8.5 ± 12.8 dB SPL at 20.0 kHz. No improvement in performance was visible across the procedure. While the thresholds at 0.5 and 4.0 kHz were in line with the previous literature, the threshold at 20 kHz was remarkably lower than expected. Dogs' ability to produce vocalization beyond 20 kHz, potentially used in short-range communication, and the selective pressure linked to intraspecific communication in social canids are discussed as potential explanations for the sensitivity to higher frequencies.

Crossmodal associations between naturally occurring tactile and sound textures.

This study investigates the crossmodal associations between naturally occurring sound textures and tactile textures. Previous research has demonstrated the association between low-level sensory features of sound and touch, as well as higher-level, cognitively mediated associations involving language, emotions, and metaphors. However, stimuli like textures, which are found in both modalities have received less attention. In this study, we conducted two experiments: a free association task and a two alternate forced choice task using everyday tactile textures and sound textures selected from natural sound categories. The results revealed consistent crossmodal associations reported by participants between the textures of the two modalities. They tended to associate more sound textures (e.g., wood shavings and sandpaper) with tactile surfaces that were rated as harder, rougher, and intermediate on the sticky-slippery scale. While some participants based the auditory-tactile association on sensory features, others made the associations based on semantic relationships, co-occurrence in nature, and emotional mediation. Interestingly, the statistical features of the sound textures (mean, variance, kurtosis, power, autocorrelation, and correlation) did not show significant correlations with the crossmodal associations, indicating a higher-level association. This study provides insights into auditory-tactile associations by highlighting the role of sensory and emotional (or cognitive) factors in prompting these associations.

Attention-Driven Modulation of Auditory Cortex Activity during Selective Listening in a Multispeaker Setting.

Real-world listening settings often consist of multiple concurrent sound streams. To limit perceptual interference during selective listening, the auditory system segregates and filters the relevant sensory input. Previous work provided evidence that the auditory cortex is critically involved in this process and selectively gates attended input toward subsequent processing stages. We studied at which level of auditory cortex processing this filtering of attended information occurs using functional magnetic resonance imaging (fMRI) and a naturalistic selective listening task. Forty-five human listeners (of either sex) attended to one of two continuous speech streams, presented either concurrently or in isolation. Functional data were analyzed using an inter-subject analysis to assess stimulus-specific components of ongoing auditory cortex activity. Our results suggest that stimulus-related activity in the primary auditory cortex and the adjacent planum temporale are hardly affected by attention, whereas brain responses at higher stages of the auditory cortex processing hierarchy become progressively more selective for the attended input. Consistent with these findings, a complementary analysis of stimulus-driven functional connectivity further demonstrated that information on the to-be-ignored speech stream is shared between the primary auditory cortex and the planum temporale but largely fails to reach higher processing stages. Our findings suggest that the neural processing of ignored speech cannot be effectively suppressed at the level of early cortical processing of acoustic features but is gradually attenuated once the competing speech streams are fully segregated.

Finding tau rhythms in EEG: An independent component analysis approach.

Tau rhythms are largely defined by sound responsive alpha band (~8-13 Hz) oscillations generated largely within auditory areas of the superior temporal gyri. Studies of tau have mostly employed magnetoencephalography or intracranial recording because of tau's elusiveness in the electroencephalogram. Here, we demonstrate that independent component analysis (ICA) decomposition can be an effective way to identify tau sources and study tau source activities in EEG recordings. Subjects (N = 18) were passively exposed to complex acoustic stimuli while the EEG was recorded from 68 electrodes across the scalp. Subjects' data were split into 60 parallel processing pipelines entailing use of five levels of high-pass filtering (passbands of 0.1, 0.5, 1, 2, and 4 Hz), three levels of low-pass filtering (25, 50, and 100 Hz), and four different ICA algorithms (fastICA, infomax, adaptive mixture ICA [AMICA], and multi-model AMICA [mAMICA]). Tau-related independent component (IC) processes were identified from this data as being localized near the superior temporal gyri with a spectral peak in the 8-13 Hz alpha band. These "tau ICs" showed alpha suppression during sound presentations that was not seen for other commonly observed IC clusters with spectral peaks in the alpha range (e.g., those associated with somatomotor mu, and parietal or occipital alpha). The choice of analysis parameters impacted the likelihood of obtaining tau ICs from an ICA decomposition. Lower cutoff frequencies for high-pass filtering resulted in significantly fewer subjects showing a tau IC than more aggressive high-pass filtering. Decomposition using the fastICA algorithm performed the poorest in this regard, while mAMICA performed best. The best combination of filters and ICA model choice was able to identify at least one tau IC in the data of ~94% of the sample. Altogether, the data reveal close similarities between tau EEG IC dynamics and tau dynamics observed in MEG and intracranial data. Use of relatively aggressive high-pass filters and mAMICA decomposition should allow researchers to identify and characterize tau rhythms in a majority of their subjects. We believe adopting the ICA decomposition approach to EEG analysis can increase the rate and range of discoveries related to auditory responsive tau rhythms.

Atypical brain responses to 40-Hz click trains in girls with Rett syndrome: Auditory steady-state response and sustained wave.

AIM: The current study aimed to infer neurophysiological mechanisms of auditory processing in children with Rett syndrome (RTT)-rare neurodevelopmental disorders caused by MECP2 mutations. We examined two brain responses elicited by 40-Hz click trains: auditory steady-state response (ASSR), which reflects fine temporal analysis of auditory input, and sustained wave (SW), which is associated with integral processing of the auditory signal. METHODS: We recorded electroencephalogram findings in 43 patients with RTT (aged 2.92-17.1 years) and 43 typically developing children of the same age during 40-Hz click train auditory stimulation, which lasted for 500 ms and was presented with interstimulus intervals of 500 to 800 ms. Mixed-model ancova with age as a covariate was used to compare amplitude of ASSR and SW between groups, taking into account the temporal dynamics and topography of the responses. RESULTS: Amplitude of SW was atypically small in children with RTT starting from early childhood, with the difference from typically developing children decreasing with age. ASSR showed a different pattern of developmental changes: the between-group difference was negligible in early childhood but increased with age as ASSR increased in the typically developing group, but not in those with RTT. Moreover, ASSR was associated with expressive speech development in patients, so that children who could use words had more pronounced ASSR. CONCLUSION: ASSR and SW show promise as noninvasive electrophysiological biomarkers of auditory processing that have clinical relevance and can shed light onto the link between genetic impairment and the RTT phenotype.

Temporal Ordering and Auditory Resolution in Individuals with Sensorineural Hearing Loss.

Introduction Peripheral hearing loss, besides causing inadequate auditory input, can lead to distortions in the tonotopic auditory map and reorganization of neural networks. Therefore, the processing of temporal aspects of a sound stimulus and, consequently, the effectiveness of human communication can be negatively impacted. Objective To test the temporal ordering and auditory resolution of people with mild and moderate sensorineural hearing loss and to compare them with the those of people with normal hearing. Methods A total of 19 right-handed individuals aged 16 to 59 years with mild to moderate postlingually acquired symmetric bilateral sensorineural hearing loss participated in the study. They were submitted to frequency and duration pattern tests and a random gap detection test. Results The mean correct response rate in the frequency pattern test was of 66.3%, and, in the duration pattern test, 71.7%. The mean threshold in the random gap detection test was of 14.1 ms. A comparison with the criteria established for normal subjects without peripheral hearing loss revealed that more than half the subjects had abnormal results in the temporal ordering test, while a smaller fraction had reduced temporal resolution. Conclusions The performance of the subjects with acquired sensorineural hearing loss was poorer than that of the participants without peripheral hearing loss. Their results on the temporal ordering test were also poorer than in the temporal resolution test, demonstrating the importance of analyzing both these auditory skills in people with peripheral hearing loss.

Altered hierarchical auditory predictive processing after lesions to the orbitofrontal cortex.

Orbitofrontal cortex (OFC) is classically linked to inhibitory control, emotion regulation, and reward processing. Recent perspectives propose that the OFC also generates predictions about perceptual events, actions, and their outcomes. We tested the role of the OFC in detecting violations of prediction at two levels of abstraction (i.e., hierarchical predictive processing) by studying the event-related potentials (ERPs) of patients with focal OFC lesions (n = 12) and healthy controls (n = 14) while they detected deviant sequences of tones in a local-global paradigm. The structural regularities of the tones were controlled at two hierarchical levels by rules defined at a local (i.e., between tones within sequences) and at a global (i.e., between sequences) level. In OFC patients, ERPs elicited by standard tones were unaffected at both local and global levels compared to controls. However, patients showed an attenuated mismatch negativity (MMN) and P3a to local prediction violation, as well as a diminished MMN followed by a delayed P3a to the combined local and global level prediction violation. The subsequent P3b component to conditions involving violations of prediction at the level of global rules was preserved in the OFC group. Comparable effects were absent in patients with lesions restricted to the lateral PFC, which lends a degree of anatomical specificity to the altered predictive processing resulting from OFC lesion. Overall, the altered magnitudes and time courses of MMN/P3a responses after lesions to the OFC indicate that the neural correlates of detection of auditory regularity violation are impacted at two hierarchical levels of rule abstraction.

Behavioral entrainment to rhythmic auditory stimulation can be modulated by tACS depending on the electrical stimulation field properties.

Synchronization between auditory stimuli and brain rhythms is beneficial for perception. In principle, auditory perception could be improved by facilitating neural entrainment to sounds via brain stimulation. However, high inter-individual variability of brain stimulation effects questions the usefulness of this approach. Here we aimed to modulate auditory perception by modulating neural entrainment to frequency modulated (FM) sounds using transcranial alternating current stimulation (tACS). In addition, we evaluated the advantage of using tACS montages spatially optimized for each individual's anatomy and functional data compared to a standard montage applied to all participants. Across two different sessions, 2 Hz tACS was applied targeting auditory brain regions. Concurrent with tACS, participants listened to FM stimuli with modulation rate matching the tACS frequency but with different phase lags relative to the tACS, and detected silent gaps embedded in the FM sound. We observed that tACS modulated the strength of behavioral entrainment to the FM sound in a phase-lag specific manner. Both the optimal tACS lag and the magnitude of the tACS effect were variable across participants and sessions. Inter-individual variability of tACS effects was best explained by the strength of the inward electric field, depending on the field focality and proximity to the target brain region. Although additional evidence is necessary, our results also provided suggestive insights that spatially optimizing the electrode montage could be a promising tool to reduce inter-individual variability of tACS effects. This work demonstrates that tACS effectively modulates entrainment to sounds depending on the optimality of the electric field. However, the lack of reliability on optimal tACS lags calls for caution when planning tACS experiments based on separate sessions.

What is a Rhythm for the Brain? The Impact of Contextual Temporal Variability on Auditory Perception.

Temporal predictions can be formed and impact perception when sensory timing is fully predictable: for instance, the discrimination of a target sound is enhanced if it is presented on the beat of an isochronous rhythm. However, natural sensory stimuli, like speech or music, are not entirely predictable, but still possess statistical temporal regularities. We investigated whether temporal expectations can be formed in non-fully predictable contexts, and how the temporal variability of sensory contexts affects auditory perception. Specifically, we asked how "rhythmic" an auditory stimulation needs to be in order to observe temporal predictions effects on auditory discrimination performances. In this behavioral auditory oddball experiment, participants listened to auditory sound sequences where the temporal interval between each sound was drawn from gaussian distributions with distinct standard deviations. Participants were asked to discriminate sounds with a deviant pitch in the sequences. Auditory discrimination performances, as measured with deviant sound discrimination accuracy and response times, progressively declined as the temporal variability of the sound sequence increased. Moreover, both global and local temporal statistics impacted auditory perception, suggesting that temporal statistics are promptly integrated to optimize perception. Altogether, these results suggests that temporal predictions can be set up quickly based on the temporal statistics of past sensory events and are robust to a certain amount of temporal variability. Therefore, temporal predictions can be built on sensory stimulations that are not purely periodic nor temporally deterministic.

Negative Space: An Alternative Framework for Archaeoacoustics.

Hearing the remote past seems impossible. Archaeoacoustics is a contemporary field intent on reconstructing the evolution of early communication systems, offering the possibility of developing methodologies relating to past sound signaling and music. Through a contribution of the emerging sensory field of archaeoacoustics and an example of acoustic assessments conducted at the site of Coves del Toll, can we understand signals of the past in order to investigate human behaviour and trace its cognitive evolution? This paper explores alternative methodological and theoretical approaches to understanding prehistoric sonic behaviours in early hominids and aims to set out a framework to theoretically and philosophically approach the "sound record" of the past. The theoretical proposition of this paper integrates the musical and sound art disciplines of spectralism and sound ecology to challenge the current limitations of listening to sound.

Listening to trees in the forest: Attentional set influences how semantic and acoustic factors interact in auditory perception.

Studies of auditory object perception claim that semantic properties dominate acoustic properties in determining identification accuracy. Yet the direction of the semantic effect is mixed, with some studies showing an advantage for detecting incongruent sounds and others reporting a congruent sound advantage. Here we examine the role of the participant's attentional set when identifying auditory objects in naturalistic soundscapes. We varied the acoustic and semantic properties of the sounds orthogonally in two experiments. In Experiment 1 participants tuned their attention broadly to detect any change between two successive soundscapes (e.g., two restaurant soundscapes, with and without a child coughing). In Experiment 2 they tuned attention more narrowly to a probe presented after a soundscape (e.g., a restaurant soundscape with a child coughing, followed by the coughing sound alone). In both experiments, semantic relations between the objects and backgrounds helped to disambiguate objects that blended acoustically with the background. When attending globally (Experiment 1), objects that were acoustically similar yet semantically incongruent tended to be missed (e.g., bouncing basketball on a construction site), as though camouflaged by the gist of the soundscape. When attending locally (Experiment 2), semantically congruent foil objects led to false positive reports under acoustically similar conditions (hammering sounds on a construction site), as though the gist of the soundscape contributed to their plausible inclusion. In summary, although attentional set had a strong influence on the specific kinds of errors made, both results pointed to participants using a semantically congruent high-level schema to report the sounds they heard.

Generating New Musical Preferences From Multilevel Mapping of Predictions to Reward.

Much of what we know and love about music hinges on our ability to make successful predictions, which appears to be an intrinsically rewarding process. Yet the exact process by which learned predictions become pleasurable is unclear. Here we created novel melodies in an alternative scale different from any established musical culture to show how musical preference is generated de novo. Across nine studies (n = 1,185), adult participants learned to like more frequently presented items that adhered to this rapidly learned structure, suggesting that exposure and prediction errors both affected self-report liking ratings. Learning trajectories varied by music-reward sensitivity but were similar for U.S. and Chinese participants. Furthermore, functional MRI activity in auditory areas reflected prediction errors, whereas functional connectivity between auditory and medial prefrontal regions reflected both exposure and prediction errors. Collectively, results support predictive coding as a cognitive mechanism by which new musical sounds become rewarding.

Auditory training for tinnitus treatment: a scoping review.

OBJECTIVES: Our study aimed to verify the evidence of auditory training employed in the audiological treatment of tinnitus in adults and older adults. METHODS: Scoping review based on a search for articles in journals available in MEDLINE (PubMed), Embase (Elsevier), LILACS (BVS), and Cochrane Library. Titles and abstracts of the retrieved articles were assessed by peers, following the eligibility criteria; they were afterward read in full text, and the references were hand searched in the results found. Studies' level of evidence was classified into very high (Level A+), high (Level A), moderate (Level B), limited (Level C), low (Level D), or very low (Level D-) based on the Critically Appraised Topics. RESULTS: 2160 records were identified in the searching stage and 15 studies were eligible for data extraction. Study design, sample characterization, auditory training tasks, sound stimuli, outcome measures, and results were extracted. Frequency discrimination training was the most frequent strategy, followed by auditory attentional skills training and multisensory training. Almost all studies with daily auditory training sessions reported significant benefits demonstrated in at least one outcome measure. Studies that used auditory discrimination training and attentional auditory skill stimulation to treat tinnitus obtained quality evidence levels ranging from limited to high (C‒A) and studies that applied multisensory training or attentional training combined with counseling and passive listening in tinnitus patients reached a high-quality evidence level (A). CONCLUSION: Recent studies had higher levels of evidence and considered attentional factors and multisensory pathways in auditory training strategies.

Self-initiation enhances perceptual processing of auditory stimuli in an online study.

Understanding how the brain incorporates sensory and motor information will enable better theory building on human perception and behavior. In this study, we aimed to estimate the influence of predictive mechanisms on the magnitude and variability of sensory attenuation in two online samples. After the presentation of a visual cue stimulus, participants (Experiment 1: N = 224, Experiment 2: N = 84) compared the loudness of two consecutive tones in a two-alternative forced-choice task. In Experiment 1, the first tone was either self-initiated or not; in Experiment 2, the second tone was either self-initiated or not (active and passive condition, respectively). We further manipulated identity prediction (i.e., the congruence of pre-learned cue-sound combinations; congruent vs. incongruent), and the duration of the onset delay (to account for effects of attentional differences between the passive and active condition, 50 ms vs. 0 ms). We critically discuss our results within the framework of both classical (i.e., motor-based forward models) and contemporary approaches (i.e., predictive processing framework). Contrary to our preregistered hypothesis, we observed enhanced perceptual processing, instead of attenuation, for self-initiated auditory sensory input. Further, our results reveal an effect of fixed sound delays on the processing of motor and non-motor-based predictive information, and may point to according shifts in attention, leading to a perceptual bias. These results might best be captured by a hybrid explanatory model, combining predictions based on self-initiated motor action with a global predictive mechanism.

Auditory training for tinnitus treatment: a scoping review

Abstract Objectives Our study aimed to verify the evidence of auditory training employed in the audiological treatment of tinnitus in adults and older adults. Methods Scoping review based on a search for articles in journals available in MEDLINE (PubMed), Embase (Elsevier), LILACS (BVS), and Cochrane Library. Titles and abstracts of the retrieved articles were assessed by peers, following the eligibility criteria; they were afterward read in full text, and the references were hand searched in the results found. Studies' level of evidence was classified into very high (Level A+), high (Level A), moderate (Level B), limited (Level C), low (Level D), or very low (Level D−) based on the Critically Appraised Topics. Results 2160 records were identified in the searching stage and 15 studies were eligible for data extraction. Study design, sample characterization, auditory training tasks, sound stimuli, outcome measures, and results were extracted. Frequency discrimination training was the most frequent strategy, followed by auditory attentional skills training and multisensory training. Almost all studies with daily auditory training sessions reported significant benefits demonstrated in at least one outcome measure. Studies that used auditory discrimination training and attentional auditory skill stimulation to treat tinnitus obtained quality evidence levels ranging from limited to high (C‒A) and studies that applied multisensory training or attentional training combined with counseling and passive listening in tinnitus patients reached a high-quality evidence level (A). Conclusion Recent studies had higher levels of evidence and considered attentional factors and multisensory pathways in auditory training strategies.

White noise effect on listening effort among patients with chronic tinnitus and normal hearing thresholds

Abstract Objective This study investigated the effects of WN on LE in subjects with chronic tinnitus and normal hearing thresholds. The study was a prospective, non-randomized, before-and-after, intra-participant intervention. Methods Twenty-five subjects performed the following tests: conventional and high-frequency audiometry, acuphenometry, screening questionnaires for depression and anxiety symptoms, Tinnitus Handicap Inventory (THI), Montreal Cognitive Assessment, and high WM test from the Working Memory Assessment Battery, Federal University of Minas Gerais (WMAB) as the LE measure in two conditions: No Added Noise (NAN) and with Added Noise (AN). Results Seventeen participants (68%) performed better on AN condition. Data analysis revealed a 45% improvement in the WMAB total span count on AN setting, with a significant p value (p = 0.001). Conclusion The subgroup of participants without traces of anxiety symptoms, up to mild traces of depressive symptoms, having unilateral tinnitus, and a THI level up to grade 2, had improved WM performance in the presence of WN, which suggests a release of cognitive resources and less auditory effort under these combined conditions. Evidence level 4.

Central auditory processing and aphasia: A scoping review / Processamento auditivo central e afasia: uma revisão de escopo

ABSTRACT Purpose: to report scientific evidence on the impact of aphasia on central auditory processing and map the contribution of auditory training to aphasic individuals. Methods: a scoping review approaching national and international databases (SciELO, LILACS, PubMed, Scopus, and Cochrane Library) and the gray literature (Google Scholar and Open Grey). The inclusion criteria covered articles that addressed the interface between central auditory processing and aphasia, excluding duplicates, literature reviews, and scientific abstracts. Literature Review: the review comprised 13 articles that met the eligibility criteria for this study. Seven of the selected articles assessed central auditory processing, four used electrophysiological examinations (such as auditory brainstem response and long-latency auditory evoked potentials) to assess the auditory pathway, and only one analyzed the intervention in aphasic individuals with auditory training. Conclusion: scientific evidence points to an important change in aphasic people's central auditory processing, with impaired figure-ground, auditory closure, temporal resolution and ordering, and binaural integration. Moreover, it is relevant to assess auditory processing, given the contribution of auditory training in speech-language-hearing therapy for a better prognosis in the rehabilitation of aphasia.

RESUMO Objetivo: reportar as evidências científicas do impacto da afasia no Processamento Auditivo Central e mapear a contribuição do Treinamento Auditivo para a população afásica. Métodos: trata-se de uma revisão de escopo realizada nas bases de dados nacionais e internacionais: Scielo, Lilacs, Pubmed, Scopus, Cochrane Library e com uma busca adicional à literatura cinzenta no Google Scholar e Open Grey. Os critérios de inclusão abrangeram artigos que abordassem a interface do processamento auditivo central e afasia, excluindo-se as duplicações, artigos de revisão da literatura e resumos científicos. Revisão de Literatura: selecionaram-se 13 artigos que cumpriram os critérios de elegibilidade deste estudo. Dos artigos selecionados, sete apresentaram a avaliação do Processamento Auditivo Central, quatro apresentaram os exames eletrofisiológicos - como os exames de Potencial Evocado Auditivo de Tronco Encefálico (PEATE) e Potencial Evocado Auditivo de Longa Latência (PEALL) - para avaliação da via auditiva e apenas um estudo analisou a intervenção dos indivíduos afásicos por meio do treinamento auditivo. Conclusão: as evidências científicas apontam importante alteração no Processamento Auditivo Central dos afásicos, apresentando prejuízos nas habilidades auditivas de figura-fundo, fechamento auditivo, resolução e ordenação temporal e integração binaural. Ainda, demonstra-se como relevante a avaliação do processamento, devido à contribuição do Treinamento Auditivo nas terapias fonoaudiológicas para um melhor prognóstico na reabilitação das afasias.

Modificações do feedback auditivo e seus efeitos sobre a voz de indivíduos adultos: uma revisão de escopo / Modifications of auditory feedback and its effects on the voice of adult subjects: a scoping review

RESUMO Introdução A percepção auditiva da voz e sua produção envolvem o feedback auditivo, as pistas cinestésicas e o sistema de feedforward, os quais produzem efeitos distintos para a voz. Os efeitos Lombard, Sidetone e o Pitch-Shift-Reflex são os mais estudados. O mapeamento de experimentos científicos sobre as modificações do feedback auditivo para o controle motor da voz possibilita examinar a literatura existente sobre o fenômeno e pode contribuir para o treinamento ou terapias da voz. Objetivo Mapear os experimentos e resultados das pesquisas com manipulação do feedback auditivo para o controle motor da voz de indivíduos adultos. Método Revisão de escopo seguindo o Checklist Preferred Reporting Items for Systematic reviews and Meta-Analyses extension (PRISMA-ScR) para responder à pergunta: "Quais os métodos de investigação e principais achados das pesquisas sobre a manipulação do feedback auditivo no automonitoramento da voz de indivíduos adultos?". O protocolo de busca foi baseado na estratégia mnemônica População, Conceito e Contexto (PCC). A população são os indivíduos adultos; o conceito é a manipulação do feedback auditivo e o contexto é o controle motor da voz. Os artigos foram pesquisados nas bases de dados: BVS/ Biblioteca Virtual em Saúde, MEDLINE/Medical Literature Analysis and Retrieval Sistem on-line, COCHRANE, CINAHL/Cumulative Index to Nursing and Allied Health Literature, SCOPUS e WEB OF SCIENCE. Resultados Foram encontrados 60 artigos, sendo 19 da temática do Efeito Lombard, 25 do efeito Pitch-shift-reflex, 12 do efeito Sidetone e quatro sobre o efeito Sidetone/Lombard. Os estudos são concordantes que a inserção de um ruído que mascara o feedback auditivo provoca um aumento na intensidade de fala do indivíduo e que a amplificação do feedback auditivo promove a redução do nível de pressão sonora na produção da voz. Observa-se uma resposta reflexa à mudança de tom no feedback auditivo, porém, com características individuais em cada estudo. Conclusão O material e método dos experimentos são distintos, não há padronizações nas tarefas, as amostras são variadas, muitas vezes reduzidas. A diversidade metodológica dificulta a generalização dos resultados. Os principais achados das pesquisas a respeito o feedback auditivo sobre o controle motor da voz confirmam que, na supressão do feedback auditivo, o indivíduo tende a aumentar a intensidade da voz. Na amplificação do feedback auditivo, o indivíduo diminui a intensidade e tem maior controle sobre a frequência fundamental e, nas manipulações da frequência, o indivíduo tende a corrigir a manipulação. Os poucos estudos com sujeitos disfônicos mostram que eles se comportam diferentemente dos não disfônicos.

ABSTRACT Introduction The auditory perception of voice and its production involve auditory feedback, kinesthetic cues and the feedforward system that produce different effects for the voice. The Lombard, Sidetone and Pitch-Shift-Reflex effects are the most studied. The mapping of scientific experiments on changes in auditory feedback for voice motor control makes it possible to examine the existing literature on the phenomenon and may contribute to voice training or therapies. Purpose To map experiments and research results with manipulation of auditory feedback for voice motor control in adults. Method Scope review following the Checklist Preferred Reporting Items for Systematic reviews and Meta-Analyses extension (PRISMA-ScR) to answer the question: "What are the investigation methods and main research findings on the manipulation of auditory feedback in voice self-monitoring of adults?". The search protocol was based on the Population, Concept, and Context (PCC) mnemonic strategy, in which the population is adult individuals, the concept is the manipulation of auditory feedback and the context is on motor voice control. Articles were searched in the databases: BVS/Virtual Health Library, MEDLINE/Medical Literature Analysis and Retrieval System online, COCHRANE, CINAHL/Cumulative Index to Nursing and Allied Health Literature, SCOPUS and WEB OF SCIENCE. Results 60 articles were found, 19 on the Lombard Effect, 25 on the Pitch-shift-reflex effect, 12 on the Sidetone effect and four on the Sidetone/Lombard effect. The studies are in agreement that the insertion of a noise that masks the auditory feedback causes an increase in the individual's speech intensity and that the amplification of the auditory feedback promotes the reduction of the sound pressure level in the voice production. A reflex response to the change in pitch is observed in the auditory feedback, however, with particular characteristics in each study. Conclusion The material and method of the experiments are different, there are no standardizations in the tasks, the samples are varied and often reduced. The methodological diversity makes it difficult to generalize the results. The main findings of research on auditory feedback on voice motor control confirm that in the suppression of auditory feedback, the individual tends to increase the intensity of the voice. In auditory feedback amplification, the individual decreases the intensity and has greater control over the fundamental frequency, and in frequency manipulations, the individual tends to correct the manipulation. The few studies with dysphonic individuals show that they behave differently from non-dysphonic individuals.