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Background Parkinson's disease (PD) is a degenerative, progressive, chronic disease that mainly affects the central nervous system, caused by dopamine deficiency. One of the ways to evaluate the central nervous system is with auditory evoked potentials (AEP).

Background Multiple sclerosis (MS) is an inflammatory demyelinating disease. Auditory evoked potential studies have demonstrated conduction and neural processing deficits in adults with MS, but little is known about the electrophysiological responses in children and adolescents.

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Background/Aim. In everyday communication, people are exposed to a myriad of sounds that need to be sorted and relevant information extracted. The ability of a person to concentrate on certain sounds in a noisy background environment, perform selective attention, and focus their auditory attention is crucial for everyday functioning and communication. The aim of this study was to investigate the effect of the sensorimotor rhythm (SMR) (12–15 Hz) neurofeedback (NFB) training to improve auditory cognition measured by the achievements in the Quick speech-in-noise (QuickSIN) test, changes in the amplitudes and latencies of components of auditory evoked potentials (AEP) N100, N200, and P300 in the auditory oddball discrimination task, and changes in the spectral power of the SMR. Methods. The study included 16 healthy participants aged 25–40 years (8 males and 8 females). Each participant had 20 daily sessions of SMR NFB training. Auditory cognitive functions and electrophysiological correlates of cognitive processing were recorded 5 times – before NFB, after 5, 10, and 20 sessions, and one month after the last session of NFB. Re-sults. The results showed a statistically significant decrease in N200 and P300 latencies at frontal midline (Fz), central midline (Cz), and parietal midline (Pz) regions, an improvement on the QuickSIN test, and an increase in electroencephalogram SMR rhythm spectral power in the Cz region as a result of the NFB SMR training. No significant effect of the NFB training on the N100, N200, and P300 amplitudes on Fz, Cz, and Pz was found. Conclusion. The obtained results suggest that SMR NFB affects auditory perception in terms of shorter latencies of AEP and better performance on the QuickSIN test.

Background/Aim. Neurofeedback (NFB) training of sensorimotor rhythm (SMR) contributes to improving cognitive performance and increasing attention. SMR power is increased when a person is focused and task-oriented. The shorter reaction time (RT) of the P300 auditory evoked potentials (AEPs) is associated with better attention. Hence, the increase in SMR power after NFB SMR training should decrease the RT in a cognitive task. The aim of the study was to examine the ability of healthy individuals to modulate the SMR of electroencephalographic (EEG) activity between 12 and 15 Hz during 20-day NFB training sessions. In addition, the effect of NFB SMR training on RT was investigated. Methods. Participants were divided into experimental and control groups, with 24 subjects (12 males and 12 females) in each group, aged between 25 and 40 years. Participants in the experimental group were trained with authentic NFB SMR training, while in the control group, false (placebo) training was applied. AEPs were registered on five occasions: before NFB training, after 5, 10, and 20 training sessions, and one month after the last training. Results. The results showed that a series of 20 NFB SMR training sessions increased the amplitudes of the SMR. RT in the experimental group was significantly shortened, while in the control group, it was not observed. Moreover, the increase in the power of the EEG signal o f t he S MR showed a negative correlation with RT, but only in a subgroup of male subjects. Conclusion. The obtained results indicate the effects of NFB training on the improvement of the attention process expressed by RT.

ABSTRACT Purpose: to compare the Auditory Middle Latency Response in adults, one group with and another group without altered auditory skills. In addition, the aim was to compare cut-off values of 30% and 50% for the Ear Effect in terms of sensitivity and specificity. Methods: the sample comprised 32 individuals of both genders with no hearing loss who were divided into Group 1 (16 individuals with no alterations in auditory skills) and Group 2 (16 individuals with alterations in auditory skills). All participants received an audiological evaluation and measurement of Brainstem and Auditory Middle Latency Potentials. Results: when Group 1 and Group 2 were compared, a statistically significant difference was only observed in Na and Pa amplitude of waves A1C3 and A2C3. In the analysis of sensitivity and specificity of the Auditory Middle Latency Response, a cut-off value of 50% gave a better balance between sensitivity and specificity. Conclusion: adults presented with altered auditory abilities had smaller response amplitudes in the Na and Pa components of the waves generated in the left hemisphere. A cut-off value of 50% gave a better discrimination of the Ear Effect for identifying subjects with altered auditory skills.

The number and independence of channels in cochlear implants (CI) has long been considered to influence speech recognition, particularly in competing background noise. Measures of channel independence have been obtained via psychophysical and objective means, relying on interactions between probe and masker signals delivered on different channels. In the current study, electrically evoked compound action potentials (ECAP) obtained from 32 Nucleus CI recipients tested at one basal and one apical position were performed using a standard spread-of-excitation procedure. An alternative analysis method, comparing masked responses only, revealed distant maskers as effective or more effective than same-electrode maskers in 13/32 cases. This appears to indicate substantial crosstalk between channels, covering up to nine intracochlear electrodes in one subject. Subjects with atypical responses and no other limiting factors had significantly poorer sentence recognition in noise compared with those with no detected peripheral or cognitive limiting factors. We propose that channel crosstalk detected via ECAPs may be a biomarker for poor or patchy neural survival that leads to poorer speech perception in CI recipients., (Copyright © 2025 The Author(s). Published by Elsevier B.V. All rights reserved.)

The cortical tracking of the acoustic envelope is a phenomenon where the brain's electrical activity, as recorded by electroencephalography (EEG) signals, fluctuates in accordance with changes in stimulus intensity (the acoustic envelope of the stimulus). Understanding speech in a noisy background is a key challenge for people with hearing impairments. Speech stimuli are therefore more ecologically valid than clicks, tone pips, or speech tokens (e.g., syllables) for assessing hearing. However, it remains unclear whether EEG responses to speech provide an advantage in predicting speech intelligibility. This study aimed to assess the ability of cortical responses to speech and speech-related sounds to predict behavioural speech-in-noise performance in listeners with normal hearing when they are not attending to the stimuli. Twenty native English-speaking adults with normal hearing (aged 18 to 40 years) participated in a speech reception task, listening to English Matrix sentences presented at signal-to-noise ratios (SNRs) of -15, -10, -5, 0, and ∞ (no background noise) dB, and then identifying the words they heard in the sentences. In the EEG experiment, the participants then listened to continuous speech, broadband noise modulated by the envelope of speech, and repeating short /da/ stimuli presented at the same SNR levels as in the Matrix test. For the latter, Auditory Late Response (ALR) was estimated from the EEG, and for the former, the strength of the envelope-tracking responses was calculated. Cortical responses to all stimuli showed monotonic relationships with the signal-to-noise ratio at the group level and in most individuals, although there was considerable variability. EEG analysis in the delta band showed no significant difference in the number of participants with predicted speech reception thresholds (SRTs) within an error margin of 7 dB-the level at which SRT prediction is considered applicable-regardless of the type of cortical response used. In the theta band, however, SRT predictions based on cortical responses to continuous speech performed worse, showing a significantly lower number of predictions within an error margin of 7 dB compared to those based on cortical responses to modulated noise and the repeating /da/ sound. The proportion of individual SRT predictions with an error margin within 7 dB was, at best, 30 %. For people with normal hearing, cortical responses to continuous speech and modulated noise predicted speech-in-noise performance at the group level but not at the individual level, due to variability in cortical tracking of the acoustic envelope. Predicting the SRT on an individual level remains a major and clinically important challenge., Competing Interests: Declaration of competing interest The authors have no conflicts of interest to report., (Copyright © 2025 The Authors. Published by Elsevier B.V. All rights reserved.)

Tinnitus is the perception of a ringing, buzzing, or other sound without the presence of an external stimulus. Reduced central auditory nervous system inhibition is a commonly reported mechanism contributing to a person's tinnitus perception. Different cortical auditory evoked potential (CAEP) studies have supported the presence of reduced inhibition in people with tinnitus. Although previous CAEPs used to study tinnitus do broadly represent inhibitory function, it is not entirely clear if the different CAEPs present similarly within an individual. To address this gap in knowledge, the current study evaluated the convergent validity between different CAEPs that broadly reflect inhibitory function, called sensory gating and onset-offset CAEPs. Convergent validity between sensory gating and onset-offset CAEPs was evaluated as a function of participant tinnitus status, stimulus frequency, and CAEP quantification approach. The results indicated that sensory gating and onset-offset CAEP responses indicative of inhibitory function did not demonstrate strong convergent validity. Further, the strength of convergent validity did not differ between people with and without tinnitus. However, experimental factors that yielded more robust CAEPs, such as broadband stimuli, and more comprehensive measures of amplitude, such as total response area, resulted in better convergent validity compared to higher frequency stimuli and more isolated measures of amplitude like peak amplitude. Overall, these findings suggest that the specific inhibitory mechanisms represented by sensory gating and onset-offset CAEPs differ. Therefore, each CAEP may be better suited to study distinct populations and/or inhibitory functions., (Copyright © 2025 Elsevier B.V. All rights reserved.)

Adaptation is the attenuation of a neuronal response when a stimulus is repeatedly presented. The phenomenon has been linked to sensory memory, but its exact neuronal mechanisms are under debate. One defining feature of adaptation is its lifetime, that is, the timespan over which the attenuating effect of previous stimulation persists. This can be revealed by varying the stimulus-onset interval (SOI) of the repeated stimulus. As SOI is increased, the peak amplitude of the response grows before saturating at large SOIs. The rate of this growth can be quantified and used as an estimate of adaptation lifetime. Here, we studied whether adaptation lifetime varies across the left and the right auditory cortex of the human brain. Event-related fields of whole-head magnetoencephalograms (MEG) were measured in 14 subjects during binaural presentation of pure tone stimuli. To make statistical inferences on the single-subject level, additional event-related fields were generated by resampling the original single-trial data via bootstrapping. For each hemisphere and SOI, the peak amplitude of the N1m response was then derived from both original and bootstrap-based data sets. Finally, the N1m-peak amplitudes were used for deriving subject- and hemisphere-specific estimates of adaptation lifetime. Comparing subject-specific adaptation lifetime across hemispheres, we found a significant difference, with longer adaptation lifetimes in the left than in the right auditory cortex (p = 0.004). This difference might have a functional relevance in the context of temporal binding of auditory stimuli, leading to larger integration time windows in the left than in the right hemisphere., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Purpose: Variations in neural survival along the cochlear implant electrode array leads to off-place listening, resulting in poorer speech understanding outcomes for recipients. Therefore, it is important to develop and compare clinically viable tests to identify these patient-specific intra-cochlear neural differences., Methods: Nineteen experienced cochlear implant recipients (9 males and 10 females) were recruited for this study. We estimated the neural health along the electrode array for a group of experienced adult implant recipients using two methods: the difference between psychophysical detection thresholds in bipolar vs. monopolar mode and the panoramic electrically evoked compound action potential method (PECAP). We hypothesised that: neural health estimated using both methods at single electrodes will be correlated at the participant level and the group level; and participants with larger variations in neural health along the electrode array will have poorer speech outcomes., Results: At the individual level, the two neural measures correlated significantly across electrodes (p < 0.05) for 5 out of 15 participants. At the group level, we observed a weak but significant across-electrode correlation (R 2  = 0.111, p < 0.001). While a larger variation in neural measures estimated from psychophysical thresholds was associated with lower phoneme speech scores (R 2  = 0.499, p < 0.01), no significant association was found between variations in PECAP's neural health estimates and phoneme speech scores (R 2  = 0.082, p = 0.366)., Conclusion: Our evidence suggests that both methods likely quantify a shared underlying neural basis, hypothesised to be the neural health along the cochlear implant array. The differences between the two measures may be attributed to differences in stimulus rate or loudness used to elicit responses and/or the influence of factors arising more centrally than the auditory nerve., Competing Interests: Declarations. Ethics Approval: All the participants provided written informed consent. The experimental protocol was approved by the Human Research Ethics Committee from the Royal Victorian Eye and Ear Hospital (ethics approval: 19.1446H). Conflict of Interest: The authors declare no competing interests., (© 2024. The Author(s) under exclusive licence to Association for Research in Otolaryngology.)

Noise-induced cochlear synaptopathy has been studied for over 25 years with no known diagnosis for this disorder in humans. This type of "hidden hearing loss" induces a loss of synapses in the inner ear but no change in audiometric thresholds. Recent studies have shown that by two months post synaptopathy-inducing noise exposure, synapses in some animal species can regenerate. Animal studies to date have focused primarily on peripheral hearing measures to diagnose ribbon synapse loss, while suggesting binaural listening deficits such as speech-reception-in-noise result from this disorder, but haven't accounted for the possible regeneration of synapses. To address this, we measured binaural physiological and behavioral function, the latter utilizing the pre-pulse inhibition of acoustic startle method, in both male and female adult guinea pigs following exposure to noise that has been shown to induce cochlear synaptopathy. Physiological measurements extended to 2 months post noise exposure to characterize any deficit and subsequent recovery. While common audiological assessments showed temporary threshold shift, reduced evoked potential amplitudes indicative of synaptopathy and measurable binaural electrophysiological hearing deficits post exposure, all measures recovered by 2 months. Suspected regeneration of synaptic ribbons occurred by 2 months post exposure and cochlear histology revealed no synaptic loss 4 months post exposure. Our results show that the same noise exposure protocol demonstrated to cause synaptic loss in prior studies causes physiological binaural processing deficits in the brainstem and that the recovery of neural binaural processing coincides with the regeneration of synapses shown in previous studies and normal binaural hearing behavior., Competing Interests: Declaration of competing interest The authors report no conflicts of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The 22q11.2 deletion is a risk factor for multiple psychiatric disorders including schizophrenia and also increases vulnerability to middle-ear problems that can cause hearing impairment. Up to 60% of deletion carriers experience hearing impairment and ~30% develop schizophrenia in adulthood. It is not known if these risks interact. Here we used the Df1/+ mouse model of the 22q11.2 deletion to investigate how hearing impairment might interact with increased genetic vulnerability to psychiatric disease to affect brain function. We measured brain function using cortical auditory evoked potentials (AEPs), which are commonly measured non-invasively in humans. After identifying one of the simplest and best-validated methods for AEP measurement in mice from the diversity of previous approaches, we measured peripheral hearing sensitivity and cortical AEPs in Df1/+ mice and their WT littermates. We exploited large inter-individual variation in hearing ability among Df1/+ mice to distinguish effects of genetic background from effects of hearing impairment. Central auditory gain and adaptation were quantified by comparing brainstem activity and cortical AEPs and by analyzing the growth of cortical AEPs with increasing sound level or inter-tone interval duration. We found that level-dependent AEP growth was abnormally large in Df1/+ mice regardless of hearing impairment, but other AEP measures of central auditory gain and adaptation depended on both genotype and hearing phenotype. Our results demonstrate the relevance of comorbid hearing loss to auditory brain dysfunction in 22q11.2DS and also identify potential biomarkers for psychiatric disease that are robust to hearing impairment., Competing Interests: Competing interests: The authors declare no competing interests. Ethics approval and consent to participate: This study involved only animal research. All methods and experiments were performed in accordance with relevant guidelines and regulations of the UCL Animal Welfare and Ethical Review Body and a UK Home Office project licence approved under the United Kingdom Animals (Scientific Procedures) Act of 1986., (© 2025. The Author(s).)

Background: Children born with very low birth weight (VLBW) are at higher risk for cognitive impairment, including language deficits and sensorimotor difficulties. Voice-evoked response (P1m), which has been suggested as a language development biomarker in young children, remains unexplored for its efficacy in VLBW children. Furthermore, the relation between P1m and sensory difficulties in VLBW children remains unclear., Methods: 40 children with VLBW were recruited at 5-to-6 years old (26 male, 14 female, mean age of months ± SD, 80.0 ± 4.9). We measured their voice-evoked brain response using child-customized magnetoencephalography (MEG) and examined the relation between P1m and language conceptual inference ability and sensory characteristics., Results: The final sample comprised 36 children (23 boys, 13 girls; ages 61-86 months; gestational ages 24-36 weeks). As a result of multiple regression analysis, voice-evoked P1m in the left hemisphere was correlated significantly with language ability (β = 0.414 P = 0.015) and sensory hypersensitivity (β = 0.471 P = 0.005)., Conclusion: Our findings indicate that the relation between P1m and language conceptual inference ability observed in term children in earlier studies is replicated in VLBW children, and suggests P1m intensity as a biomarker of sensory sensitivity characteristics., Impact: We investigated brain functions related to language development and sensory problems in very low birth-weight children. In very low birth weight children at early school age, brain responses to human voices are associated with language conceptual inference ability and sensory hypersensitivity. These findings promote a physiological understanding of both language development and sensory characteristics in very low birth weight children., Competing Interests: Competing interests: The authors declare that this work is free from financial and other relationships that might cause a conflict of interest. Consent statement: The parents agreed to the participation of their child in the study with full knowledge of the experimental characteristics of the research. Written informed consent was obtained from each participant before the study. The Ethics Committee of Kanazawa University Hospital approved the methods and procedures, all of which were used in accordance with the Declaration of Helsinki., (© 2024. The Author(s).)

Background/Aim. Neurofeedback (NFB) is a therapeutic method based on monitoring the electroencephalogram (EEG) and providing feedback on the brain activity of sub-jects. The aim of the pilot study was to investigate the effect of lower-beta or sensorimotor rhythm (SMR) (12–15 Hz) NFB training on amplitudes and latencies of late auditory event-related potentials (aERP) components N100, N200, P300 in Go-No go task of auditory discrimination. Methods. Each of 9 healthy participants aged 25–40 years (4 male) had 20 daily sessions of SMR neurofeedback training. The aERP was recorded 5 times: before NFB, after 5, 10, and 20 sessions, and one m onth after the last session. Results. The results showed a statistically significant decrease in N100, N200, and P300 latencies at Fz, Cz, and Pz regions. No significant effect of NFB training on amplitudes of components N100, N200 and N300 was found. Conclusion. The obtained results suggest that NFB training exerts its effect on the processes of auditory cognition.

Introduction: Central auditory processing refers to the efficiency and effectiveness with which the central nervous system uses auditory information: it may be altered in neurological disorders and brain injuries, such as strokes. However, despite evidence of probable alterations in the pediatric population, functional abilities and post-stroke limitations are still not well documented in the literature. Objective: To analyze the findings of the electrophysiological and behavioral evaluations of central auditory processing of children and adolescents diagnosed with stroke from a reference outpatient clinic, as well as to investigate possible associations with the variables: type and location of the stroke and age group. Methods: The present study is characterized as comparative cross-sectional. The sample, for convenience, included individuals aged 7–18 years divided into two groups: study group, composed of individuals with a diagnosis of stroke, and control group, composed of individuals with typical development. The evaluation consisted of the following procedures: anamnesis, basic audiological evaluation, behavioral evaluation of the auditory processing disorder (dichotic digit test, dichotic consonant-vowel, synthetic sentence identification/pediatric speech intelligibility, gaps in noise, pitch pattern sequence, masking level difference), and electrophysiological evaluation (P300 and mismatch negativity). Results: Nineteen children and adolescents were included in the study group. The control group was composed of 19 children and adolescents with typical development. In the comparison between the groups, a worse performance is observed for the study group in all the evaluated tests, behavioral and electrophysiological. In the behavioral evaluation of central auditory processing, there was a statistical difference for all tests, except for masking level difference and dichotic digit test, binaural separation step on the left. In the electrophysiological evaluation, there was a statistical difference in the latency of mismatch negativity and P300. No associations were found between the behavioral and electrophysiological findings and the location of the stroke and age group variables. Conclusion: Children and adolescents diagnosed with stroke present a worse performance in the electrophysiological and behavioral evaluations of central auditory processing when compared to a control group.

Introduction: Sickle cell anemia has a genetic origin characterized by an autosomal recessive inheritance pattern. The nervous system may be subject to vaso-occlusion and, consequently, affect the proper functioning of the central portion of hearing., Objective: To assess central auditory skills and analyze short- and long-latency auditory evoked potentials in children with sickle cell disease., Methods: Cross-sectional study. All children had normal hearing thresholds, and their central auditory processing underwent behavioral assessment with a battery of tests involving dichotic and monotic listening, binaural interaction, and temporal processing. The electrophysiological assessment used short- and long-latency auditory evoked potentials. Descriptive statistics were performed., Results: Of the 28 subjects evaluated (mean age of 9.46 years), 18 were females and 10 were males. Central auditory processing disorder was identified in 85.7% of the children. The auditory skills of figure-ground for verbal sounds, binaural interaction, and complex temporal ordering were the most affected. An increase in the absolute latencies of Waves III and V was observed in the short-latency potential., Conclusion: Individuals with sickle cell disease have central auditory processing disorder, identified primarily by behavioral assessment., (© 2025 Wiley Periodicals LLC.)

Introduction: Recent studies have shown that musical practice and training are effective and have the potential to assist in the acquisition and improvement of auditory skills. Objective: To verify the scientific evidence on the implications of musical practice in central auditory processing. Methods: A systematic review was carried out in accordance with the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), using the Medline (Pubmed), LILACS, SciELO, BIREME, Scopus and Web of Science databases. The search period for the articles covered the last 5 years (2015–2020), without restriction of language and location. The quality of the articles was assessed, and the review included articles with a minimum score of 6 in a modified literature quality scale. Results: Initially, 1362 publications were found, of which 1338 were excluded after the title screening, 15 were excluded due to the abstract, with nine articles being analyzed in full and four of them excluded after the analysis, as they did not answer the guiding question proposed for this research. Five articles that met the proposed inclusion criteria were admitted for this research. It was found that in adults, musical ability is associated with better performance of several auditory processing skills, as well as the fact that musical training in children promoted an accelerated maturity of auditory processing and exposure to music facilitated the learning of auditory information in newborns. Conclusion: Considering the scientific evidence, it was found that the musical experience can improve specific skills of the central auditory processing, regardless of age, optimizing children’s linguistic development.

ABSTRACT Objective To analyze age-related changes in the central auditory pathway in healthy elderly individuals. Methods A prospective, quantitative cross-sectional study. The caseload comprised 18 adults (mean age, 22.78 years) and 18 elderly individuals (mean age, 66.72 years) of both sexes, who met inclusion criteria. Subjects were submitted to basic audiological evaluation and related electrophysiologic tests: brainstem auditory evoked potential with click stimulus and frequency-following response. Results Elderly individuals had higher wave and interpeak latencies (waves I, III and V and interpeaks I-V and III-V) of brainstem auditory evoked potential. Latencies of frequency following response waves A, E, F and O were also higher in elderly individuals. Frequency following response amplitudes were better in A than in D, F and O waves in these subjects. Likewise, interpeak intervals (V-A and V-O) were larger in elderly relative to adult individuals. Lower slope values were observed in elderly individuals. Conclusion Brainstem auditory evoked potential and frequency-following response allowed appropriate assessment of age-related changes in the auditory pathway. Slower neural response to auditory stimuli suggests reduced synchrony between neural structures.

Objective: To explore if experience with hearing aid (HA) amplification affects speech-evoked cortical potentials reflecting comprehension abilities., Design: N400 and late positive complex (LPC) responses as well as behavioural response times to congruent and incongruent digit triplets were measured. The digits were presented against stationary speech-shaped noise 10 dB above individually measured speech recognition thresholds. Stimulus presentation was either acoustic (digits 1-3) or first visual (digits 1-2) and then acoustic (digit 3)., Study Sample: Three groups of older participants ( N  = 3 × 15) with (1) pure-tone average hearing thresholds <25 dB HL from 500-4000 Hz, (2) mild-to-moderate sensorineural hearing loss (SNHL) but no prior HA experience, and (3) mild-to-moderate SNHL and >2 years of HA experience. Groups 2-3 were fitted with test devices in accordance with clinical gain targets., Results: No group differences were found in the electrophysiological data. N400 amplitudes were larger and LPC latencies shorter with acoustic presentation. For group 1, behavioural response times were shorter with visual-then-acoustic presentation., Conclusion: When speech audibility is ensured, comprehension-related electrophysiological responses appear intact in individuals with mild-to-moderate SNHL, regardless of prior experience with amplified sound. Further research into the effects of audibility versus acclimatisation-related neurophysiological changes is warranted.

Cochlear implants can restore the ability to understand speech in patients with profound sensorineural hearing loss. At present, it is not fully understood how cochlear implant users perceive speech and how electric hearing provided by a cochlear implant differs from acoustic hearing. Phoneme-related potentials characterize neural responses to individual instances of phonemes extracted from continuous speech. This retrospective study investigated phoneme-related potentials in cochlear implant users in a selective attention paradigm. Responses were compared between normal hearing listeners and cochlear implant users, and between attended and unattended conditions. Differences between phoneme categories were compared and a classifier was trained to predict the phoneme category from the neural representation. The phoneme-related potentials of cochlear implant users showed similar responses to the ones obtained in normal hearing listeners for early responses (< 100 ms) but not for later responses (> 100 ms) where peaks were smaller or absent. Attention led to an enhancement of the response, whereas latency was mostly not affected by attention. The temporal morphology of the response was influenced by the phonetic features of the stimulus, allowing a classification of the phoneme category based on the phoneme-related potentials. There is a clinical need for methods that can rapidly and objectively assess the speech understanding performance of cochlear implant users. Phoneme-related potentials may provide such a link between the acoustic and the neural representations of phonemes. They may also reveal the challenges of individual subjects and thus provide indications for patient-specific auditory training, rehabilitation programs or the fitting of cochlear implant parameters., Competing Interests: Declaration of competing interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024. Published by Elsevier B.V.)

The detection of novel, low probability events in the environment is critical for survival. To perform this vital task, our brain is continuously building and updating a model of the outside world; an extensively studied phenomenon commonly referred to as predictive coding. Predictive coding posits that the brain is continuously extracting regularities from the environment to generate predictions. These predictions are then used to supress neuronal responses to redundant information, filtering those inputs, which then automatically enhances the remaining, unexpected inputs. We have recently described the ability of auditory neurons to generate predictions about expected sensory inputs by detecting their absence in an oddball paradigm using omitted tones as deviants. Here, we studied the responses of individual neurons to omitted tones by presenting individual sequences of repetitive pure tones, using both random and periodic omissions, presented at both fast and slow rates in the inferior colliculus and auditory cortex neurons of anesthetized rats. Our goal was to determine whether feature-specific dependence of these predictions exists. Results showed that omitted tones could be detected at both high (8 Hz) and slow repetition rates (2 Hz), with detection being more robust at the non-lemniscal auditory pathway., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Offshore windfarms are a key means to produce clean energy as we seek to limit climate change effects. Impulsive pile driving used for their construction in shallow water environments is among the most intense anthropogenic sound sources. There is an increasing understanding that an array of marine invertebrates detects acoustic cues, yet little is known about how pile driving sound could impact their sound detection abilities. We experimentally quantified potential changes in sound sensitivity for an abundant, commercially and ecologically important squid species (Doryteuthis pealeii) exposed to actual in situ pile driving. The pile was 0.3-m diameter and 10-m long; hammer energy reached 16 kJ per strike. Sound detection thresholds were determined using auditory evoked potentials in animals with no exposure, after one 15-min or five repeated 15-min long pile driving sound sequences, corresponding to cumulative sound exposure levels of 110 and 131 dB re (1 μm s-2)2 s for acceleration and 187 and 214 dB re (1 μPa)2 s for pressure. We found no statistical evidence of temporary threshold shifts in any squid exposed to pile driving sound sequences. These results, combined with companion behavioral studies, suggest that squid may be robust to the sound impacts during offshore windfarm construction., (© 2024 Acoustical Society of America.)

Objective - To study the correlation between P1 latency and the results of clinical language tests (Reynell III and TROG-2), the latter were used as they are recommended for follow-up assessments of children with cochlear implants (Cis) by the Swedish National Quality Register for children with hearing impairment. Design - A clinical cohort study. Study sample - Cross-sectional and consecutive sampling of 49 children with CIs coming for clinical follow-up assessment from March 2017 - December 2019. Results - For all children tested, there was a significant negative correlation (Spearman's rho= -0.403, p  = 0.011) between hearing age and P1 latency. A significant correlation between P1 latency and the Reynell III result (Spearman's rho =  -0.810, p  = 0.015) was found. In the TROG-2 group, there was no significant correlation between their P1 latency and their language test results (Spearman's rho -0.239, p  = 0.196). Conclusion - This method seems to be feasible and easily accepted. The study was conducted in a heterogeneous group of children that we meet daily in our clinic. The results indicated that P1 latency has a negative correlation with language development among our youngest patients fitted with CIs and might be a clinical tool to assess the maturation of central auditory pathways.

Background and Objective: Tinnitus is a neuropathological condition that results in mild buzzing or ringing of the ears without an external sound source. Current tinnitus diagnostic methods often rely on subjective assessment and require intricate medical examinations. This study aimed to propose an interpretable tinnitus diagnostic framework using auditory late response (ALR) and electroencephalogram (EEG), inspired by the gap-prepulse inhibition (GPI) paradigm., Methods: We collected spontaneous EEG and ALR data from 44 patients with tinnitus and 47 hearing loss-matched controls using specialized hardware to capture responses to sound stimuli with embedded gaps. In this cohort study of tinnitus and control groups, we examined EEG spectral and ALR features of N-P complexes, comparing the responses to gap durations of 50 and 20 ms alongside no-gap conditions. To this end, we developed an interpretable tinnitus diagnostic model using ALR and EEG metrics, boosting machine learning architecture, and explainable feature attribution approaches., Results: Our proposed model achieved 90 % accuracy in identifying tinnitus, with an area under the performance curve of 0.89. The explainable artificial intelligence approaches have revealed gap-embedded ALR features such as the GPI ratio of N1-P2 and EEG spectral ratio, which can serve as diagnostic metrics for tinnitus. Our method successfully provides personalized prediction explanations for tinnitus diagnosis using gap-embedded auditory and neurological features., Conclusions: Deficits in GPI alongside activity in the EEG alpha-beta ratio offer a promising screening tool for assessing tinnitus risk, aligning with current clinical insights from hearing research., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Cochlear implant (CI) users experience diminished music enjoyment due to the technical limitations of the CI. Nonetheless, behavioral studies have reported that rhythmic features are well-transmitted through the CI. Still, the gradual improvement of rhythm perception after the CI switch-on has not yet been determined using neurophysiological measures. To fill this gap, we here reanalyzed the electroencephalographic responses of participants from two previous mismatch negativity studies. These studies included eight recently implanted CI users measured twice, within the first six weeks after CI switch-on and approximately three months later; thirteen experienced CI users with a median experience of 7 years; and fourteen normally hearing (NH) controls. All participants listened to a repetitive four-tone pattern (known in music as Alberti bass) for 35 min. Applying frequency tagging, we aimed to estimate the neural activity synchronized to the periodicities of the Alberti bass. We hypothesized that longer experience with the CI would be reflected in stronger frequency-tagged neural responses approaching the responses of NH controls. We found an increase in the frequency-tagged amplitudes after only 3 months of CI use. This increase in neural synchronization may reflect an early adaptation to the CI stimulation. Moreover, the frequency-tagged amplitudes of experienced CI users were significantly greater than those of recently implanted CI users, but still smaller than those of NH controls. The frequency-tagged neural responses did not just reflect spectrotemporal changes in the stimuli (i.e., intensity or spectral content fluctuating over time), but also showed non-linear transformations that seemed to enhance relevant periodicities of the Alberti bass. Our findings provide neurophysiological evidence indicating a gradual adaptation to the CI, which is noticeable already after three months, resulting in close to NH brain processing of spectrotemporal features of musical rhythms after extended CI use., Competing Interests: Declaration of competing interest All authors declare no conflict of interest., (Copyright © 2024. Published by Elsevier B.V.)

Sound localization in the front-back dimension is reported to be challenging, with individual differences. We investigated whether auditory discrimination processing in the brain differs based on front-back sound localization ability. This study conducted an auditory oddball task using speakers in front of and behind the participants. We used event-related brain potentials to examine the deviance detection process between groups that could and could not discriminate front-back sound localization. The results indicated that mismatch negativity (MMN) occurred during the deviance detection process, and P2 amplitude differed between standard and deviant locations in both groups. However, the latency of MMN was shorter in the group that could discriminate front-back sounds than in the group that could not. Additionally, N1 amplitude increased for deviant locations compared to standard ones only in the discriminating group. In conclusion, the sensory memories matching process based on traces of previously presented stimuli (MMN, P2) occurred regardless of discrimination ability. However, the response to changes in the physical properties of sounds (MMN latency, N1 amplitude) differed depending on the ability to discriminate front-back sounds. Our findings suggest that the brain may have different processing strategies for the two directions even without subjective recognition of the front-back direction of incoming sounds., Competing Interests: Declaration of competing interest None of the authors have potential conflicts of interest to be disclosed., (Copyright © 2024. Published by Elsevier B.V.)

Objective: The acoustic change complex (ACC) is a cortical auditory evoked potential (CAEP) and can be elicited by a change in an otherwise continuous sound. The ACC has been highlighted as a promising tool in the assessment of sound and speech discrimination capacity, and particularly for difficult-to-test populations such as infants with hearing loss, due to the objective nature of ACC measurements. Indeed, there is a pressing need to develop further means to accurately and thoroughly establish the hearing status of children with hearing loss, to help guide hearing interventions in a timely manner. Despite the potential of the ACC method, ACC measurements remain relatively rare in a standard clinical settings. The objective of this study was to perform an up-to-date systematic review on ACC measurements in children, to provide greater clarity and consensus on the possible methodologies, applications, and performance of this technique, and to facilitate its uptake in relevant clinical settings., Design: Original peer-reviewed articles conducting ACC measurements in children (< 18 years). Data were extracted and summarised for: (1) participant characteristics; (2) ACC methods and auditory stimuli; (3) information related to the performance of the ACC technique; (4) ACC measurement outcomes, advantages, and challenges. The systematic review was conducted using PRISMA guidelines for reporting and the methodological quality of included articles was assessed., Results: A total of 28 studies were identified (9 infant studies). Review results show that ACC responses can be measured in infants (from < 3 months), and there is evidence of age-dependency, including increased robustness of the ACC response with increasing childhood age. Clinical applications include the measurement of the neural capacity for speech and non-speech sound discrimination in children with hearing loss, auditory neuropathy spectrum disorder (ANSD) and central auditory processing disorder (CAPD). Additionally, ACCs can be recorded in children with hearing aids, auditory brainstem implants, and cochlear implants, and ACC results may guide hearing intervention/rehabilitation strategies. The review identified that the time taken to perform ACC measurements was often lengthy; the development of more efficient ACC test procedures for children would be beneficial. Comparisons between objective ACC measurements and behavioural measures of sound discrimination showed significant correlations for some, but not all, included studies., Conclusions: ACC measurements of the neural capacity to discriminate between speech and non-speech sounds are feasible in infants and children, and a wide range of possible clinical applications exist, although more time-efficient procedures would be advantageous for clinical uptake. A consideration of age and maturational effects is recommended, and further research is required to investigate the relationship between objective ACC measures and behavioural measures of sound and speech perception for effective clinical implementation., Competing Interests: Declaration of competing interest None (the authors have no financial disclosures or competing interests to disclose)., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Combining a cochlear implant with contralateral acoustic hearing typically enhances speech understanding, although this improvement varies among CI users and can lead to an interference effect. This variability may be associated with the effectiveness of the integration between electric and acoustic stimulation, which might be affected by the temporal mismatch between the two listening sides. Finding methods to compensate for the temporal mismatch might contribute to the optimal adjustment of bimodal devices and to improve hearing in CI users with contralateral acoustic hearing. The current study investigates cortical auditory evoked potentials (CAEPs) in normal hearing listeners (NH) and CI users with contralateral acoustic hearing. In NH, the amplitude of the N1 peak and the maximum phase locking value (PLV) were analyzed under monaural, binaural, and binaural temporally mismatched conditions. In CI users, CAEPs were measured when listening with CI only (CIS&#95;only), acoustically only (AS&#95;only) and with both sides together (CIS+AS). When listening with CIS+AS, various interaural delays were introduced between the electric and acoustic stimuli. In NH listeners, interaural temporal mismatch resulted in decreased N1 amplitude and PLV. Moreover, PLV is suggested as a more sensitive measure to investigate the integration of information between the two listening sides. CI users showed varied N1 latencies between the AS&#95;only and CIS&#95;only listening conditions, with increased N1 amplitude when the temporal mismatch was compensated. A tendency towards increased PLV was also observed, however, to a lesser extent than in NH listeners, suggesting a limited integration between electric and acoustic stimulation. This work highlights the potential of CAEPs measurement to investigate cortical processing of the information between two listening sides in NH and bimodal CI users., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

The current study investigated the effect of lower frequency input on stream segregation acuity in older, normal hearing adults. Using event-related brain potentials (ERPs) and perceptual performance measures, we previously showed that stream segregation abilities were less proficient in older compared to younger adults. However, in that study we used frequency ranges greater than 1500 Hz. In the current study, we lowered the target frequency range below 1500 Hz and found similar stream segregation abilities in younger and older adults. These results indicate that the perception of complex auditory scenes is influenced by the spectral content of the auditory input and suggest that lower frequency ranges of input in older adults may facilitate listening ability in complex auditory environments. These results also have implications for the advancement of prosthetic devices., Competing Interests: Declaration of competing interest None, (Copyright © 2024. Published by Elsevier B.V.)

Congenital or early-onset unilateral hearing loss (UHL) can disrupt the normal development of the auditory system. In extreme cases of UHL (i.e., single sided deafness), consistent cochlear implant use during sensitive periods resulted in cortical reorganization that partially reversed the detrimental effects of unilateral sensory deprivation. There is a gap in knowledge, however, regarding cortical plasticity i.e. the brain's capacity to adapt, reorganize, and develop binaural pathways in milder degrees of UHL rehabilitated by a hearing aid (HA). The current study was set to investigate early-stage cortical processing and electrophysiological manifestations of binaural processing by means of cortical auditory evoked potentials (CAEPs) to speech sounds, in children with moderate to severe-to-profound UHL using a HA. Fourteen children with UHL (CHwUHL), 6-14 years old consistently using a HA for 3.5 (±2.3) years participated in the study. CAEPs were elicited to the speech sounds /m/, /g/, and /t/ in three listening conditions: monaural [Normal hearing (NH), HA], and bilateral [BI (NH + HA)]. Results indicated age-appropriate CAEP morphology in the NH and BI listening conditions in all children. In the HA listening condition: (1) CAEPs showed similar morphology to that found in the NH listening condition, however, the mature morphology observed in older children in the NH listening condition was not evident; (2) P1 was elicited in all but two children with severe-to-profound hearing loss, to at least one speech stimuli, indicating effective audibility; (3) A significant mismatch in timing and synchrony between the NH and HA ear was found; (4) P1 was sensitive to the acoustic features of the eliciting stimulus and to the amplification characteristics of the HA. Finally, a cortical binaural interaction component (BIC) was derived in most children. In conclusion, the current study provides first-time evidence for cortical plasticity and partial reversal of the detrimental effects of moderate to severe-to-profound UHL rehabilitated by a HA. The derivation of a cortical biomarker of binaural processing implies that functional binaural pathways can develop when sufficient auditory input is provided to the affected ear. CAEPs may thus serve as a clinical tool for assessing, monitoring, and managing CHwUHL using a HA., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Tinnitus denotes the perception of a non-environmental sound and might result from aberrant auditory prediction. Successful prediction of formal (e.g., type) and temporal sound characteristics facilitates the filtering of irrelevant information, also labelled as 'sensory gating' (SG). Here, we explored if and how parallel manipulations of formal prediction violations and temporal predictability affect SG in persons with and without tinnitus. Age-, education- and sex-matched persons with and without tinnitus (N = 52) participated and listened to paired-tone oddball sequences, varying in formal (standard vs. deviant pitch) and temporal predictability (isochronous vs. random timing). EEG was recorded from 128 channels and data were analyzed by means of temporal spatial principal component analysis (tsPCA). SG was assessed by amplitude suppression for the 2nd tone in a pair and was observed in P50-like activity in both timing conditions and groups. Correspondingly, deviants elicited overall larger amplitudes than standards. However, only persons without tinnitus displayed a larger N100-like deviance response in the isochronous compared to the random timing condition. This result might imply that persons with tinnitus do not benefit similarly as persons without tinnitus from temporal predictability in deviance processing. Thus, persons with tinnitus might display less temporal sensitivity in auditory processing than persons without tinnitus., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024. Published by Elsevier B.V.)

Following adult-onset hearing impairment, crossmodal plasticity can occur within various sensory cortices, often characterized by increased neural responses to visual stimulation in not only the auditory cortex, but also in the visual and audiovisual cortices. In the present study, we used an established model of loud noise exposure in rats to examine, for the first time, whether the crossmodal plasticity in the audiovisual cortex that occurs following a relatively mild degree of hearing loss emerges solely from altered intracortical processing or if thalamocortical changes also contribute to the crossmodal effects. Using a combination of an established pharmacological 'cortical silencing' protocol and current source density analysis of the laminar activity recorded across the layers of the audiovisual cortex (i.e., the lateral extrastriate visual cortex, V2L), we observed layer-specific changes post-silencing in the strength of the residual visual, but not auditory, input in the noise exposed rats with mild hearing loss compared to rats with normal hearing. Furthermore, based on a comparison of the laminar profiles pre- versus post-silencing in both groups, we can conclude that noise exposure caused a re-allocation of the strength of visual inputs across the layers of the V2L cortex, including enhanced visual-evoked activity in the granular layer; findings consistent with thalamocortical plasticity. Finally, we confirmed that audiovisual integration within the V2L cortex depends on intact processing within intracortical circuits, and that this form of multisensory processing is vulnerable to disruption by noise-induced hearing loss. Ultimately, the present study furthers our understanding of the contribution of intracortical and thalamocortical processing to crossmodal plasticity as well as to audiovisual integration under both normal and mildly-impaired hearing conditions., Competing Interests: Declaration of competing interest The authors declare that there are no conflicts of interest regarding the publication of this paper., (Copyright © 2024. Published by Elsevier B.V.)

Background & Rationale: In prior work using non-speech stimuli, children with hearing loss show impaired perception of binaural cues and no significant change in cortical responses to bilateral versus unilateral stimulation. Aims of the present study were to: 1) identify bilateral responses to envelope and spectral components of a speech syllable using the frequency-following response (FFR), 2) determine if abnormalities in the bilateral FFR occur in children with hearing loss, and 3) assess functional consequences of abnormal bilateral FFR responses on perception of binaural timing cues., Methods: A single-syllable speech stimulus (/dα/) was presented to each ear individually and bilaterally. Participants were 9 children with normal hearing (M Age = 12.1 ± 2.5 years) and 6 children with bilateral hearing loss who were experienced bilateral hearing aid users (M Age = 14.0 ± 2.6 years). FFR temporal and spectral peak amplitudes were compared between listening conditions and groups using linear mixed model regression analyses. Behavioral sensitivity to binaural cues were measured by lateralization responses as coming from the right or left side of the head., Results: Both temporal and spectral peaks in FFR responses increased in amplitude in the bilateral compared to unilateral listening conditions in children with normal hearing. These measures of "bilateral advantage" were reduced in the group of children with bilateral hearing loss and associated with decreased sensitivity to interaural timing differences., Conclusion: This study is the first to show that bilateral responses in both temporal and spectral domains can be measured in children using the FFR and is altered in children with hearing loss with consequences to binaural hearing., (Copyright © 2024. Published by Elsevier B.V.)

Neurons within a neuronal network can be grouped by bottom-up and top-down influences using synchrony in neuronal oscillations. This creates the representation of perceptual objects from sensory features. Oscillatory activity can be differentiated into stimulus-phase-locked (evoked) and non-phase-locked (induced). The former is mainly determined by sensory input, the latter by higher-level (cortical) processing. Effects of auditory deprivation on cortical oscillations have been studied in congenitally deaf cats (CDCs) using cochlear implant (CI) stimulation. CI-induced alpha, beta, and gamma activity were compromised in the auditory cortex of CDCs. Furthermore, top-down information flow between secondary and primary auditory areas in hearing cats, conveyed by induced alpha oscillations, was lost in CDCs. Here we used the matching pursuit algorithm to assess components of such oscillatory activity in local field potentials recorded in primary field A1. Additionally to the loss of induced alpha oscillations, we also found a loss of evoked theta activity in CDCs. The loss of theta and alpha activity in CDCs can be directly related to reduced high-frequency (gamma-band) activity due to cross-frequency coupling. Here we quantified such cross-frequency coupling in adult 1) hearing-experienced, acoustically stimulated cats (aHCs), 2) hearing-experienced cats following acute pharmacological deafening and subsequent CIs, thus in electrically stimulated cats (eHCs), and 3) electrically stimulated CDCs. We found significant cross-frequency coupling in all animal groups in > 70% of auditory-responsive sites. The predominant coupling in aHCs and eHCs was between theta/alpha phase and gamma power. In CDCs such coupling was lost and replaced by alpha oscillations coupling to delta/theta phase. Thus, alpha/theta oscillations synchronize high-frequency gamma activity only in hearing-experienced cats. The absence of induced alpha and theta oscillations contributes to the loss of induced gamma power in CDCs, thereby signifying impaired local network activity., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Tinnitus, the perception of sound with no external auditory stimulus, is a complex, multifaceted, and potentially devastating disorder. Despite recent advances in our understanding of tinnitus, there are limited options for effective treatment. Tinnitus treatments are made more complicated by the lack of a test for tinnitus based on objectively measured physiological characteristics. Such an objective test would enable a greater understanding of tinnitus mechanisms and may lead to faster treatment development in both animal and human research. This review makes the argument that an objective tinnitus test, such as a non-invasive electrophysiological measure, is desperately needed. We review the current tinnitus assessment methods, the underlying neural correlates of tinnitus, the multiple tinnitus generation theories, and the previously investigated electrophysiological measurements of tinnitus. Finally, we propose an alternate objective test for tinnitus that may be valid in both animal and human subjects., Competing Interests: Declaration of competing interest The authors have a patent pending for the development of a ‘long-duration sound test’ that could be used as a tool to test for tinnitus., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Older listeners have difficulty processing temporal cues that are important for word discrimination, and deficient processing may limit their ability to benefit from these cues. Here, we investigated aging effects on perception and neural representation of the consonant transition and the factors that contribute to successful perception. To further understand the neural mechanisms underlying the changes in processing from brainstem to cortex, we also examined the factors that contribute to exaggerated amplitudes in cortex. We enrolled 30 younger normal-hearing and 30 older normal-hearing participants who met the criteria of clinically normal hearing. Perceptual identification functions were obtained for the words BEAT and WHEAT on a 7-step continuum of consonant-transition duration. Auditory brainstem responses (ABRs) were recorded to click stimuli and frequency-following responses (FFRs) and cortical auditory-evoked potentials were recorded to the endpoints of the BEAT-WHEAT continuum. Perceptual performance for identification of BEAT vs. WHEAT did not differ between younger and older listeners. However, both subcortical and cortical measures of neural representation showed age group differences, such that FFR phase locking was lower but cortical amplitudes (P1 and N1) were higher in older compared to younger listeners. ABR Wave I amplitude and FFR phase locking, but not audiometric thresholds, predicted early cortical amplitudes. Phase locking to the transition region and early cortical peak amplitudes (P1) predicted performance on the perceptual identification function. Overall, results suggest that the neural representation of transition durations and cortical overcompensation may contribute to the ability to perceive transition duration contrasts. Cortical overcompensation appears to be a maladaptive response to decreased neural firing/synchrony., (Copyright © 2024 Elsevier B.V. All rights reserved.)

ABSTRACT Purpose: to monitor, with long-latency auditory evoked potentials, the plasticity of the central auditory pathways in adults and older adults, new users of hearing aids. Methods: a total of 15 adults and older adults, aged 55 to 85 years, participated in the research. They had a symmetric bilateral mild to moderate sensorineural hearing loss, without previous experience with any type of hearing aid. The long-latency auditory evoked potentials were conducted with and without amplification, at 60 and 75 dBnHL, with speech stimulus in a sound field, in two assessment moments: up to one week after fitting the hearing aid and after six months of its use. The Student’s t-test was used for statistical analysis, considering significant the p-value < 0.05. Results: responses with lower latency values were observed for the right ear in the second assessment. Comparing the first with the second assessment, both with and without the hearing aid, an increase in the amplitude of P2-N2 was observed, as well as an increase in the latency of the P2 component at the intensity of 75 dBnHL. No statistically significant differences were observed at the intensity of 60 dBnHL. Conclusion:the use of the hearing aid promoted the plasticity of the central auditory pathways, increasing the number of neurons responsive to the sound stimuli.

Objective The tests of three types of auditory evoked potentials （AEPs） were performed on normal young adults, to understand the frequency characteristics of different testing methods and the relationship between response threshold and pure tone audiometry threshold of different methods, and to discuss the forensic value of 3 types of AEPs to evaluate hearing function. Methods Twenty normal young adults were selected, their standard pure tone audiometry threshold, short-term pure tone audiometry threshold and the response threshold of 3 types of AEPs （tone burst-auditory brainstem response, 40 Hz auditory event-related potential and slow vertex response） at 0.5 kHz, 1.0 kHz, 2.0 kHz and 4.0 kHz were recorded. The relationship between the response threshold and standard pure tone audiometry threshold, short-term pure tone audiometry threshold of 3 types of AEPs at different frequencies as well as the differences between different types of AEPs were analyzed. Results The short-term pure tone audiometry threshold was higher than the standard pure tone audiometry threshold at each frequency. The response threshold and standard pure tone audiometry threshold of the 3 types of AEPs all had a certain correlation, and the response threshold of the 3 types of AEPs was higher than short-term pure tone audiometry threshold and standard pure tone audiometry threshold at each frequency. The differences in the differences between the response threshold and standard pure tone audiometry threshold of the 3 types of AEPs at different frequencies had statistical significance. Linear regression mathematical models were established to infer the standard pure tone audiometry threshold （hearing level） from response threshold （sound pressure level） of 3 types of AEPs of normal young adults. Conclusion When using response threshold of different types of AEPs to estimate pure tone audiometry threshold, conversion and correction are needed. Combined use of different types of AEPs could improve the accuracy of hearing function evaluation.

The brain's ability to encode temporal patterns and predict upcoming events is critical for speech perception and other aspects of social communication. Deficits in predictive coding may contribute to difficulties with social communication and overreliance on repetitive predictable environments in individuals with autism spectrum disorder (ASD). Using a mismatch negativity (MMN) task involving rhythmic tone sequences of varying complexity, we tested the hypotheses that (1) individuals with ASD have reduced MMN response to auditory stimuli that deviate in presentation timing from expected patterns, particularly as pattern complexity increases and (2) amplitude of MMN signal is inversely correlated with level of impairment in social communication and repetitive behaviors. Electroencephalography was acquired as individuals (age 6–21 years) listened to repeated five‐rhythm tones that varied in the Shannon entropy of the rhythm across three conditions (zero, medium‐1 bit, and high‐2 bit entropy). The majority of the tones conformed to the established rhythm (standard tones); occasionally the fourth tone was temporally shifted relative to its expected time of occurrence (deviant tones). Social communication and repetitive behaviors were measured using the Social Responsiveness Scale and Repetitive Behavior Scale‐Revised. Both neurotypical controls (n = 19) and individuals with ASD (n = 21) show stepwise decreases in MMN as a function of increasing entropy. Contrary to the result forecasted by a predictive coding hypothesis, individuals with ASD do not differ from controls in these neural mechanisms of prediction error to auditory rhythms of varied temporal complexity, and there is no relationship between these signals and social communication or repetitive behavior measures. Lay summary We tested the idea that the brain's ability to use previous experience to influence processing of sounds is weaker in individuals with autism spectrum disorder (ASD) than in neurotypical individuals. We found no difference between individuals with ASD and neurotypical controls in brain wave responses to sounds that occurred earlier than expected in either simple or complex rhythms. There was also no relationship between these brain waves and social communication or repetitive behavior scores. [ABSTRACT FROM AUTHOR]

Abstract Introduction Studies using the Brainstem Auditory Evoked Potential with speech stimulus are increasing in Brazil, and there are divergences between the methodologies used for testing. Objectives To analyze the parameters used in the study of the Brainstem Auditory Evoked Potentials with speech stimulus. Data Synthesis The survey was performed using electronic databases. The search strategy was as follows: “Evoked potentials, auditory” OR “Brain stem” OR “Evoked potentials, auditory, brain stem” AND “Speech.” The survey was performed from June to July of 2016. The criteria used for including articles in this study were: being written in Portuguese, English or Spanish; presenting the description of the testing parameters and the description of the sample. In the databases selected, 2,384 articles were found, and 43 articles met all of the inclusion criteria. The predominance of the following parameters was observed to achieve the potential during study: stimulation with the syllable /da/; monaural presentation with greater use of the right ear; intensity of 80 dB SPL; vertical placement of electrodes; use of in-ear headphones; patient seated, distracted in awake state; alternating polarity; use of speech synthesizer software for the elaboration of stimuli; presentation rate of 10.9/s; and sampling rate of 20 kHz. Conclusions The theme addressed in this systematic review is relatively recent. However, the results are significant enough to encourage the use of the procedure in clinical practice and advise clinicians about the most used procedures in each parameter.