Background: It is assumed that speech comprehension deficits in background noise are caused by age-related or acquired hearing loss. Methods: We examined young, middle-aged, and older individuals with and without hearing threshold loss using pure-tone (PT) audiometry, short-pulsed distortion-product otoacoustic emissions (pDPOAEs), auditory brainstem responses (ABRs), auditory steady-state responses (ASSRs), speech comprehension (OLSA), and syllable discrimination in quiet and noise. Results: A noticeable decline of hearing sensitivity in extended high-frequency regions and its influence on low-frequency-induced ABRs was striking. When testing for differences in OLSA thresholds normalized for PT thresholds (PTTs), marked differences in speech comprehension ability exist not only in noise, but also in quiet, and they exist throughout the whole age range investigated. Listeners with poor speech comprehension in quiet exhibited a relatively lower pDPOAE and, thus, cochlear amplifier performance independent of PTT, smaller and delayed ABRs, and lower performance in vowel-phoneme discrimination below phase-locking limits (/o/-/u/). When OLSA was tested in noise, listeners with poor speech comprehension independent of PTT had larger pDPOAEs and, thus, cochlear amplifier performance, larger ASSR amplitudes, and higher uncomfortable loudness levels, all linked with lower performance of vowel-phoneme discrimination above the phase-locking limit (/i/-/y/). Conslusions: This study indicates that listening in noise in humans has a sizable disadvantage in envelope coding when basilar-membrane compression is compromised. Clearly, and in contrast to previous assumptions, both good and poor speech comprehension can exist independently of differences in PTTs and age, a phenomenon that urgently requires improved techniques to diagnose sound processing at stimulus onset in the clinical routine.

The 40 Hz auditory steady-state response (ASSR), an oscillatory brain response to periodically modulated auditory stimuli, is a promising, noninvasive physiological biomarker for schizophrenia and related neuropsychiatric disorders. The 40 Hz ASSR might be amplified by synaptic interactions in cortical circuits, which are, in turn, disturbed in neuropsychiatric disorders. Here, we tested whether the 40 Hz ASSR in the human auditory cortex depends on two key synaptic components of neuronal interactions within cortical circuits: excitation via N-methyl-aspartate glutamate (NMDA) receptors and inhibition via gamma-amino-butyric acid (GABA) receptors. We combined magnetoencephalography (MEG) recordings with placebo-controlled, low-dose pharmacological interventions in the same healthy human participants (13 males, 7 females). All participants exhibited a robust 40 Hz ASSR in auditory cortices, especially in the right hemisphere, under a placebo. The GABAA receptor-agonist lorazepam increased the amplitude of the 40 Hz ASSR, while no effect was detectable under the NMDA blocker memantine. Our findings indicate that the 40 Hz ASSR in the auditory cortex involves synaptic (and likely intracortical) inhibition via the GABAA receptor, thus highlighting its utility as a mechanistic signature of cortical circuit dysfunctions involving GABAergic inhibition.

Objective. The auditory steady-state response (ASSR) allows estimation of hearing thresholds. The ASSR can be estimated from electroencephalography (EEG) recordings from electrodes positioned on both the scalp and within the ear (ear-EEG). Ear-EEG can potentially be integrated into hearing aids, which would enable automatic fitting of the hearing device in daily life. The conventional stimuli for ASSR-based hearing assessment, such as pure tones and chirps, are monotonous and tiresome, making them inconvenient for repeated use in everyday situations. In this study we investigate the use of natural speech sounds for ASSR estimation.Approach.EEG was recorded from 22 normal hearing subjects from both scalp and ear electrodes. Subjects were stimulated monaurally with 180 min of speech stimulus modified by applying a 40 Hz amplitude modulation (AM) to an octave frequency sub-band centered at 1 kHz. Each 50 ms sub-interval in the AM sub-band was scaled to match one of 10 pre-defined levels (0-45 dB sensation level, 5 dB steps). The apparent latency for the ASSR was estimated as the maximum average cross-correlation between the envelope of the AM sub-band and the recorded EEG and was used to align the EEG signal with the audio signal. The EEG was then split up into sub-epochs of 50 ms length and sorted according to the stimulation level. ASSR was estimated for each level for both scalp- and ear-EEG.Main results. Significant ASSRs with increasing amplitude as a function of presentation level were recorded from both scalp and ear electrode configurations.Significance. Utilizing natural sounds in ASSR estimation offers the potential for electrophysiological hearing assessment that are more comfortable and less fatiguing compared to existing ASSR methods. Combined with ear-EEG, this approach may allow convenient hearing threshold estimation in everyday life, utilizing ambient sounds. Additionally, it may facilitate both initial fitting and subsequent adjustments of hearing aids outside of clinical settings.

Prominent pathological hypotheses for schizophrenia include auditory processing deficits and dysconnectivity within cerebral networks. However, most neuroimaging studies have focused on impairments in either resting-state or task-related functional connectivity in patients with schizophrenia. The aims of our study were to examine (1) blood oxygen level-dependent (BOLD) signals during auditory steady-state response (ASSR) tasks, (2) functional connectivity during the resting-state and ASSR tasks and (3) state shifts between the resting-state and ASSR tasks in patients with schizophrenia. To reduce the functional consequences of scanner noise, we employed resting-state and sparse sampling auditory fMRI paradigms in 25 schizophrenia patients and 25 healthy controls. Auditory stimuli were binaural click trains at frequencies of 20, 30, 40 and 80 Hz. Based on the detected ASSR-evoked BOLD signals, we examined the functional connectivity between the thalamus and bilateral auditory cortex during both the resting state and ASSR task state, as well as their alterations. The schizophrenia group exhibited significantly diminished BOLD signals in the bilateral auditory cortex and thalamus during the 80 Hz ASSR task (corrected p < 0.05). We observed a significant inverse relationship between the resting state and ASSR task state in altered functional connectivity within the thalamo-auditory network in schizophrenia patients. Specifically, our findings demonstrated stronger functional connectivity in the resting state (p < 0.004) and reduced functional connectivity during the ASSR task (p = 0.048), which was mediated by abnormal state shifts, within the schizophrenia group. These results highlight the presence of abnormal thalamocortical connectivity associated with deficits in the shift between resting and task states in patients with schizophrenia.

This meta-analysis investigates auditory steady-state responses (ASSRs) as potential biomarkers of schizophrenia, focusing on previously unexplored clinical populations, frequencies, and variables. We examined 37 studies, encompassing a diverse cohort of 1788 patients with schizophrenia, including 208 patients with first-episode psychosis, 281 at-risk individuals, and 1603 healthy controls. The results indicate moderate reductions in 40 Hz ASSRs in schizophrenia patients, with significantly greater reductions in first-episode psychosis patients and minimal changes in at-risk individuals. These results call into question the expected progression of ASSR alterations across all stages of schizophrenia. The analysis also revealed the sensitivity of ASSR alterations at 40 Hz to various factors, including stimulus type, level of analysis, and attentional focus. In conclusion, our research highlights ASSRs, particularly at 40 Hz, as potential biomarkers of schizophrenia, revealing varied implications across different stages of the disorder. This study enriches our understanding of ASSRs in schizophrenia, highlighting their potential diagnostic and therapeutic relevance, particularly in the early stages of the disease.

BACKGROUND: Electrophysiological tests are often used to evaluate hearing loss in infants and young children with conductive hearing loss, no matter to quantify or characterize. However, there are advantages and disadvantages associated with the various electrophysiological tests that are currently available. Therefore, there is no gold standard test. This study aimed to compare the value of narrow-band (NB) CE-Chirp-induced auditory steady-state response (ASSR) and auditory brainstem response (ABR) for assessing hearing thresholds in children with conductive hearing loss. We hope to identify an effective electrophysiological testing method to evaluate conductive hearing loss and provide a reference for clinical hearing assessment of infants with conductive hearing loss.
METHODS: and Methods: We selected 27 children (41 ears) aged 3-6 years with otitis media with effusion (OME). Within 1 day, they underwent behavioral audiometry and NB CE-Chirp-induced ASSR and ABR tests in sequence. Pearson\'s correlation analysis was performed to compare behavioral audiometry thresholds and ASSR and ABR response thresholds at 500, 1000, 2000, and 4000 Hz.
RESULTS: The behavioral audiometry thresholds of all children were strongly correlated with the response thresholds of the two electrophysiological tests, with correlation coefficients of 0.659, 0.605, 0.723, and 0.857 for ASSR, and 0.587, 0.684, 0.753, and 0.802 for ABR. The proportion of children with a difference of ≤10 dB between ASSR and behavioral audiometry thresholds or between ABR and behavioral audiometry thresholds was not high, especially in the low frequencies. ABR results were superior to ASSR results in terms of predicting actual hearing levels. At 0.5, 1, 2, and 4 kHz, the average differences between the behavioral hearing thresholds and ASSR thresholds in the 41 ears were 5.6, 5.7, 2, and 5.6 dB, respectively. The average differences between behavioral hearing thresholds and ABR thresholds was -5.6, -1.4, -6.8, and 3.2 dB, respectively. The hearing loss configuration of the ASSR exhibited a peaked pattern, similar to behavioral audiometry, whereas the ABR exhibited an ascending pattern. The time to perform the single-ear ASSR test was 5.9 min, whereas the ABR test took 17.0 min.
CONCLUSIONS: ASSR and ABR induced by the NB CE-Chirp correlated well with behavioral audiometry in children with conductive hearing loss. The NB CE-Chirp ASSR has advantages in terms of testing time and hearing configuration evaluation, whereas ABR has better reliability than ASSR. However, the stability of ASSR and ABR induced by the NB CE-Chirp is poor, and the thresholds obtained cannot replace behavioral audiometry in evaluating the true hearing of children with conductive hearing loss. However, ASSR and ABR can be used as auxiliary tests for cross-validation.

Gamma oscillations, thought to arise from the activity of ɣ-aminobutyric acid (GABA)ergic interneurons, have potential as a biomarker for schizophrenia. Gamma-band auditory steady-state responses (ASSRs) are notably reduced in both chronic and early-stage schizophrenia patients. Furthermore, alterations in gamma-band ASSRs have been demonstrated in animal models through translational research. However, the 40-Hz harmonic responses of the 20-Hz ASSR are not as well-characterized, despite the possibility that these harmonic oscillatory responses may reflect resonant activity in neural circuits. In this study, we investigated the 40-Hz harmonic response to the 20-Hz ASSR in the early stages of schizophrenia. The study recruited 49 participants, including 15 individuals at ultra-high-risk (UHR) for psychosis, 13 patients with first-episode schizophrenia (FES), and 21 healthy controls (HCs). The 40-Hz harmonic responses of the 20-Hz ASSR were evident in all groups. Interestingly, while previous report observed reduced 40-Hz ASSRs, the 40-Hz harmonic responses of the 20-Hz ASSR were not reduced in the UHR or FES groups. These findings suggest that the gamma-band ASSR and its harmonic responses may represent distinct aspects of pathophysiology in the early stages of schizophrenia.

The clinical protocol of audiological assessment in infants was prepared by the workgroup of Russian pediatric audiologists from different regions. The goal of the protocol is unification approaches to audiological diagnosis of the infants. The protocol has been developed according the evidence based medicine principles, by reviewing current scientific publications on the topic and taking into account the order of providing medical services and other clinical practice guidelines. When direct evidence was not available, both indirect evidence and consensus practice were considered in making recommendations. This guideline is not intended to serve as a standard to dictate precisely how the child should be diagnosed. This guideline is meant to provide the evidence base from which the clinician can make individualized decisions for each patient. The first part of the protocol covers following sections: equipment, staff requirements, timing of the diagnostics, case history and risk factors, preparing the child for the appointment, sedation and general anesthesia, otoscopy, tympanometry and acoustic reflex, otoacoustic emissions, skin preparing, electrode montage, choosing the stimulators, auditory brainstem responses on broadband and narrow-band stimuli, on bone conducted stimuli, auditory steady-state responses, masking, combined correction factors.
Группой российских специалистов в области детской сурдологии из различных регионов разработан протокол аудиологического обследования детей первого года жизни. Цель протокола — унифицировать подход к комплексному аудиологическому обследованию детей первого года жизни. Протокол разработан с учетом принципов доказательной медицины путем изучения современных научных публикаций в периодической печати по теме и в соответствии с порядком оказания медицинской помощи, клиническими рекомендациями. В случае отсутствия доказательной базы рекомендации вырабатывались на основании мнения экспертного сообщества. Данный протокол не является стандартом или нормативным актом, а лишь предоставляет доказательную базу, основываясь на которой клиницист может выработать индивидуальную тактику для конкретного пациента. Первая часть протокола охватывает следующие разделы: техническое оснащение, требования к персоналу, сроки обследования, сбор анамнеза и выявление факторов риска, подготовка ребенка к обследованию, седация и наркоз, отоскопия, импедансометрия, регистрация отоакустической эмиссии, обработка кожи, выбор и монтаж электродов и преобразователей, регистрация коротколатентных слуховых вызванных потенциалов на широкополосные и частотно-специфичные стимулы, на стимулы по костной проводимости, стационарные слуховые вызванные потенциалы, маскировка при электрофизиологическом обследовании, экстраполяция поведенческих порогов слышимости по порогам регистрации слуховых вызванных потенциалов.

The auditory steady-state response (ASSR) is a cortical oscillation induced by trains of 40 Hz acoustic stimuli. While the ASSR has been widely used in clinic measurement, the underlying neural mechanism remains poorly understood. In this study, we investigated the contribution of different stages of auditory thalamocortical pathway-medial geniculate body (MGB), thalamic reticular nucleus (TRN), and auditory cortex (AC)-to the generation and regulation of 40 Hz ASSR in C57BL/6 mice of both sexes. We found that the neural response synchronizing to 40 Hz sound stimuli was most prominent in the GABAergic neurons in the granular layer of AC and the ventral division of MGB (MGBv), which were regulated by optogenetic manipulation of TRN neurons. Behavioral experiments confirmed that disrupting TRN activity has a detrimental effect on the ability of mice to discriminate 40 Hz sounds. These findings revealed a thalamocortical mechanism helpful to interpret the results of clinical ASSR examinations.Significance Statement Our study contributes to clarifying the thalamocortical mechanisms underlying the generation and regulation of the auditory steady-state response (ASSR), which is commonly used in both clinical and neuroscience research to assess the integrity of auditory function. Combining a series of electrophysiological and optogenetic experiments, we demonstrate that the generation of cortical ASSR is dependent on the lemniscal thalamocortical projections originating from the ventral division of medial geniculate body to the GABAergic interneurons in the granule layer of the auditory cortex. Furthermore, the thalamocortical process for ASSR is strictly regulated by the activity of thalamic reticular nucleus (TRN) neurons. Behavioral experiments confirmed that dysfunction of TRN would cause a disruption of mice\'s behavioral performance in the auditory discrimination task.

The most popular objective physiologic test for detecting hearing loss that is in use today is the ABR, however it is not frequency specific. The frequency specific tool available for evaluation of hearing is ASSR. The study is aimed to assess the ability of ASSR to estimate hearing thresholds and identify the ideal modulation frequency in hearing impaired personnel. All subjects and controls were subjected to PTA to determine presence/absence of hearing loss, and the nature and configuration of the hearing loss if any. The subjects were then subjected to ASSR testing to objectively ascertain hearing thresholds. The PTA thresholds obtained and the hearing thresholds obtained by ASSR were correlated in this study. The study was carried out in 100 subjects under the age of 50 years (50 with normal hearing & 50 with impaired hearing by PTA) after obtaining informed consent. Moderate correlation was found between PTA and ASSR thresholds only in certain frequencies while in other frequencies the correlation though present, was low. This study concluded that ASSR system could be used to estimate hearing thresholds only approximately as no significant linear correlations were found between PTA thresholds and ASSR at the tested frequencies.