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Sleeping animals can be woken up rapidly by external threat signals, which is an essential defense mechanism for survival. However, neuronal circuits underlying the fast transmission of sensory signals for this process remain unclear. Here, we report in mice that alerting sound can induce rapid awakening within hundreds of milliseconds and that glutamatergic neurons in the pontine central gray (PCG) play an important role in this process. These neurons exhibit higher sensitivity to auditory stimuli in sleep than wakefulness. Suppressing these neurons results in reduced sound-induced awakening and increased sleep in intrinsic sleep/wake cycles, whereas their activation induces ultra-fast awakening from sleep and accelerates awakening from anesthesia. Additionally, the sound-induced awakening can be attributed to the propagation of auditory signals from the PCG to multiple arousal-related regions, including the mediodorsal thalamus, lateral hypothalamus, and ventral tegmental area. Thus, the PCG serves as an essential distribution center to orchestrate a global auditory network to promote rapid awakening. [Display omitted] • PCG glutamatergic neurons contribute to sound-induced rapid awakening • They exhibit higher sensitivity in sleep and modulate intrinsic sleep/wake states • Their activation induces ultra-fast awakening from NREM sleep • PCG transmits auditory signals to a multitude of arousal-related brain regions The ability to rapidly wake up from sleep upon threat signals is critical for animal survival. In this study, Wei et al. report that the pontine central gray (PCG) is a critical node of a fast-execution alerting system and globally broadcasts alerting auditory signals to a distributed brain network to promote awakening. [ABSTRACT FROM AUTHOR]

Sound occurs when vibrations travel through a medium. These vibrations, their propagation, and their interaction with the environment are dictated by laws of physics, and indirectly reflect underlying physical properties of things in the world. The sense of audition exists to measure sound and infer its causes in the world, so as to help organisms interact with the world around them. Audition is thus indirectly but intimately shaped by the physics of sound. In this primer, Josh McDermott, Vinayak Agarwal, and James Traer provide an overview of how physical principles shape sound in the world, and how implicit knowledge of these principles guides our sense of hearing. [ABSTRACT FROM AUTHOR]

Anesthesia modifies sensory representations in the thalamo-cortical circuit but is considered to have a milder impact on peripheral sensory processing. Here, tracking the same neurons across wakefulness and isoflurane or ketamine medetomidine anesthesia, we show that the amplitude and sign of single neuron responses to sounds are massively modified by anesthesia in the cochlear nucleus of the brainstem, the first relay of the auditory system. The reorganization of activity is so profound that decoding of sound representation under anesthesia is not possible based on awake activity. However, population-level parameters, such as average tuning strength and population decoding accuracy, are weakly affected by anesthesia, explaining why its effect has previously gone unnoticed when comparing independently sampled neurons. Together, our results indicate that the functional organization of the auditory brainstem largely depends on the network state and is ill-defined under anesthesia. This demonstrates a remarkable sensitivity of an early sensory stage to anesthesia, which is bound to disrupt downstream processing. [ABSTRACT FROM AUTHOR]

Polymer piezoelectrics with high electromechanical energy conversion (HEEC) are very promising for flexible acoustoelectric devices. However, reducing thickness and improving ordered polarization and ferroelectricity while maintaining high mechanical strength pose enormous fabrication challenges for polymer piezoelectric membranes—additionally, noise management in the acoustoelectric conversion remains an open issue. Here, we present a hydro-levitation superspreading approach for fabricating polymer nanomembranes with ordered crystalline phases and sub-nanostructures on the water surface. The elastic piezoelectric nanomembrane (EPN) is only 335 nanometers thick and consists of a conductance-stable piezoelectric layer sandwiched between two elastic damping layers. Such an all-in-one EPN can reduce background noise with low autocorrelation in the environment, suppress spurious noise caused by poor circuit contact, and achieve bandpass filtering of acoustic signals at human voice frequencies. This nanomembrane holds promise in repairing the auditory system of patients with tympanic membrane perforation and in a wide range of other acoustoelectric conversion fields. Creating flexible acoustoelectric devices with ultrathin thickness, high elasticity, stable conductivity, and high electromechanical energy conversion capability poses a challenge. Zhang et al. present a liquid crystal mediated technique that creates an elastic piezoelectric nanomembrane with double noise reduction, offering promise for auditory system reconstruction and other acoustoelectric conversion applications. [ABSTRACT FROM AUTHOR]

Age‐related hearing impairment (ARHI) is commonly associated with decreased auditory temporal resolution caused by auditory neurodegeneration. Age‐related deterioration in gap detection ability, resulting in poor temporal auditory processing, is often attributed to pathophysiological changes in both the peripheral and central auditory systems. This study aimed to investigate whether the gap detection ability declines in the early stages of ageing and to determine its usefulness in detecting peripheral and central auditory degeneration. The study used 1‐month‐old (1 M), 6‐month‐old (6 M) and 12‐month‐old (12 M) mice to examine changes in gap detection ability and associated auditory pathophysiology. Although hearing thresholds did not significantly differ between the groups, the amplitude of auditory brainstem response (ABR) wave I decreased significantly in an age‐dependent manner, consistent with age‐related cochlear synaptopathy. The relative ABR amplitude ratio of waves 2 and 5 to wave 1 was significantly increased in 12 M mice, indicating that the central auditory system had increased in relative neuroactivity. A significant increase in gap detection thresholds was observed in 12 M mice compared to 1 M mice. Although cochlear synaptopathy and central hyperactivity were positively correlated with gap detection thresholds, central hyperactivity strongly influenced gap detection ability. In the cochlear nucleus and auditory cortex, the inhibitory synaptic expression of GAD65 and the expression of parvalbumin were significantly decreased in 12 M mice, consistent with central hyperactivity. Evaluating gap detection performance may allow the identification of decreased auditory temporal resolution in the early stages of ARHI, which is strongly associated with auditory neurodegeneration. [ABSTRACT FROM AUTHOR]

Understanding cognitive processes in the brain demands sophisticated models capable of replicating neural dynamics at large scales. We present a physiologically inspired speech recognition architecture, compatible and scalable with deep learning frameworks, and demonstrate that end-to-end gradient descent training leads to the emergence of neural oscillations in the central spiking neural network. Significant cross-frequency couplings, indicative of these oscillations, are measured within and across network layers during speech processing, whereas no such interactions are observed when handling background noise inputs. Furthermore, our findings highlight the crucial inhibitory role of feedback mechanisms, such as spike frequency adaptation and recurrent connections, in regulating and synchronizing neural activity to improve recognition performance. Overall, on top of developing our understanding of synchronization phenomena notably observed in the human auditory pathway, our architecture exhibits dynamic and effcient information processing, with relevance to neuromorphic technology. [ABSTRACT FROM AUTHOR]

With the developing technology and mechanization, the number of industrial facilities has increased. It is important for the worker's physical and mental health to be in suitable working conditions. This paper analyses the regulations applied in the examination and evaluation of the acoustic environment in industrial facilities. The European Parliament and Council Directive, the United States, Singapore, Canada, Australia, Mexico, Japan, and WHO principles were analysed in detail. Simultaneously, analyses were conducted on the auditory perception of the workers in industrial facilities. As a result of the study, 85, 87, and 90 dBA noise exposure levels were determined for 8 h in different regulations examined. It has been determined that the regulative systems for the auditory perception of the workers in industrial facilities are insufficient. It was found necessary to develop regulation systems for evaluating noise exposure levels and the auditory perception of the workers together. It is important for the occupational health and safety of workers to develop a holistic approach in the update and revision of international regulation and to evaluate the control mechanisms within this scope. The protection of mental and physical health of the workers is presented as the most fundamental requirement. Moreover, it should be ensured that the noise control measures that can be taken (at the source, at the transmission path, and at the receiver) are formed by reducing the noise exposure and increasing the auditory perception of the workers in a positive view. [ABSTRACT FROM AUTHOR]

The detrimental effects of high‐intensity noise on the auditory system and emotional status, including the induction of anxiety, are well documented. Preclinical as well as epidemiological and clinical studies have solidly established differential responses between males and females to various stressful stimuli, including high‐intensity white noise (HIWN). However, whether chronic exposure to noise affects cognitive functions and whether this effect is sex dependent has not been adequately addressed. In this study, we used two cognitive test paradigms, such as the Morris water maze (MWM) and the multi‐branch maze (MBM), to test the effect of chronic HIWN on indices of spatial learning and memory in both male and female Wistar rats. Our findings indicate that daily (1 h) exposure to 100 dB of noise for 30 consecutive days induces different task‐dependent responses in male versus female rats. For example, in the acquisition phase of MWM, female rats exposed to noise outperformed their male counterparts at twice the speed. Similarly, in the MBM test, noise‐exposed female rats outperformed the male rats in reaching the nest box. It is clear from these studies that noise impairs cognitive functions twice as negatively in male rats as in female rats. Thus, sex‐related differences in spatial learning and memory in response to HIWN must be taken into consideration when investigating the neurobiological components and/or treatment modalities. [ABSTRACT FROM AUTHOR]

Aims: Cochlear implantation is a potential intervention for individuals with severe to profound hearing loss, in particular in the pediatric population. This literature review aims to comprehensively evaluate the applications of electrophysiological tests in enhancing cochlear implant (CI) outcomes for children. Methods: A literature review searched Medline and PubMed databases for articles on electrophysiological tests in CI children, using the terms "electrophysiological tests," "children," and "cochlear implant." The systematic search leads to 72 eligible texts. Results: Electrophysiological tests can be used to test CI children without the need for their active participation. These tests can be helpful in identifying and improving the health of deaf children in various ways, such as determining the CI functional status, the semantic integration effects in CI children, the effect of central auditory structures in speech stimulus processing, the development of lexical-semantic in CI children, and tracking the maturation of the central auditory system. CI enhances central auditory nervous system (CANS) maturation and auditory/language skills. Conclusion: The quality of electrophysiological tests can be improved to enhance hearing outcome prediction, postoperative physiology understanding, and hearing loss mechanisms. Electrophysiological tests study CANS maturation, identify lesions, aid CI programming, determine prognosis, and treatment outcomes. [ABSTRACT FROM AUTHOR]

Within species, vocal and auditory systems presumably coevolved to converge on a critical temporal acoustic structure that can be best produced and perceived. While dogs cannot produce articulated sounds, they respond to speech, raising the question as to whether this heterospecific receptive ability could be shaped by exposure to speech or remains bounded by their own sensorimotor capacity. Using acoustic analyses of dog vocalisations, we show that their main production rhythm is slower than the dominant (syllabic) speech rate, and that human–dog-directed speech falls halfway in between. Comparative exploration of neural (electroencephalography) and behavioural responses to speech reveals that comprehension in dogs relies on a slower speech rhythm tracking (delta) than humans' (theta), even though dogs are equally sensitive to speech content and prosody. Thus, the dog audio-motor tuning differs from humans', and we hypothesise that humans may adjust their speech rate to this shared temporal channel as means to improve communication efficacy. Human-to-pet communication requires speech processing by the animal and adjustments of the human speaking rate to match their pet's receptive abilities. This study shows that dogs and humans share similar but not identical speech processing mechanisms and that dog-human vocal interactions match dogs' sensory-motor tuning. [ABSTRACT FROM AUTHOR]

This study aimed to elucidate the long-term impact of prelingual deafness and elderly age at cochlear implantation on cochlear implant (CI) programming parameters and CI thresholds We retrospectively reviewed patients who underwent cochlear implantation less than 5 years (Prelingual group) and equal and more than 18 years in our institute. The latter group was further divided into Adult and Elderly groups according to whether the patient was younger or older than 65 at implantation. From 152, 69, and 55 patients in the Prelingual, Adult, and Elderly groups, 242, 92, and 58 ears were included. We compared CI thresholds and CI programming parameters, including impedances, T/C levels, and dynamic ranges for 8 years after implantation between the Prelingual, Adult, and Elderly groups. The Prelingual group showed consistently lower CI thresholds than the Adult and Elderly groups during the postoperative 2-8 years, but no difference was detected between the Elderly and Adult groups, except at the postoperative 4 years. The elderly group's CI thresholds did not deteriorate until postoperative 8 years. The Prelingual group showed consistently larger T/C levels (minimum/maximum current strength from CI), especially C levels, than the other two groups. At the same time, there was no significant difference between the Elderly and Adult groups except for smaller dynamic ranges in the Elderly group until postoperative 2 years. These results in the CI programming parameters might explain the lower CI thresholds in the Prelingual group than in the other groups. Focusing on CI maps 1 and 3 years after implantation, the strength of the T/C levels was similar for all channels in the Prelingual group, but the Adult and Elderly groups showed larger electrical stimuli in channels responsible for the middle frequencies than those for the lower or higher frequencies. Our results suggest a significant influence of prelingual deafness but less impact of elderly age at implantation on long-term CI programming parameters and CI thresholds. The larger C levels and lower CI thresholds in the Prelingual group than in the Adult and Elderly groups implied that CI children with prelingual deafness tolerate and prefer larger CI stimuli, which may reflect the CI-dependent development of their auditory system before the critical period. No age-related reduction in hearing thresholds was observed in the Elderly group, probably because the CI compensates for age-related dysfunction of the peripheral auditory system. [ABSTRACT FROM AUTHOR]

Aim: To Assess the involvement of Peripheral and Central Brainstem Auditory Pathways in Hypertension Patients Materials & Methods: Eligibility Criteria for Hypertension Patients in the Study: BP > 140/90 mmHg, as per JNC 7 Guidelines, and Under Control with Antihypertensive Medications. Subjects with Acute Illness were excluded. Informed Written Consent Acquisition. Informed Written Consent Acquisition in the Study was made to Ensure Ethical Participation. Exclusion Criteria and Instrumentation in the Study: Patients with associated diseases (e.g., Diabetes Mellitus, Ischemic Heart Disease, Cerebrovascular Disease) or auditory abnormalities were excluded. Medicaid Neuroperfect plus Instrument was utilized, and electrodes were placed following the 10-20 international system of EEG electrode placement. The parameters include: 1. Absolute latency of all the waves from I to V 2. Interpeak latency I-III, I-V and III-V Result: The results of the study indicate that the Absolute Latency of Wave I in the hypertensive group showed a statistically significant prolongation, with a P value of 0.0001. This suggests that there is a notable delay in the auditory nerve response in these individuals compared to the control group. The statistically significant prolongation observed in the latency values of Waves I, V, Inter-peak latency I-V, and Inter-peak latency III-V highlights the impact of hypertension on auditory function and warrants further investigation for a better understanding of the underlying mechanisms. Conclusion: Individuals with hypertension show measurable delays in auditory nerve responses and the conduction of auditory signals along brainstem pathways. Further research in this area may enhance understanding of underlying mechanisms and explore innovative approaches to manage auditory abnormalities in hypertensive patients. [ABSTRACT FROM AUTHOR]

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The present study aims to investigate whether begging calls elicit specific auditory responses in non-parenting birds, whether these responses are influenced by the hormonal status of the bird, and whether they reflect biparental care for offspring in the European starling (Sturnus vulgaris). An fMRI experiment was conducted to expose non-parenting male and female European starlings to recordings of conspecific nestling begging calls during both artificially induced breeding and non-breeding seasons. This response was compared with their reaction to conspecific individual warbling song motifs and artificial pure tones, serving as social species-specific and artificial control stimuli, respectively. Our findings reveal that begging calls evoke a response in non-parenting male and female starlings, with significantly higher responsiveness observed in the right Field L and the Caudomedial Nidopallium (NCM), regardless of season or sex. Moreover, a significant seasonal variation in auditory brain responses was elicited in both sexes exclusively by begging calls, not by the applied control stimuli, within a ventral midsagittal region of NCM. This heightened response to begging calls, even in nonparenting birds, in the right primary auditory system (Field L), and the photoperiod induced hormonal neuromodulation of auditory responses to offspring's begging calls in the secondary auditory system (NCM), bears resemblance to mammalian responses to hunger calls. This suggests a convergent evolution aimed at facilitating swift adult responses to such calls crucial for offspring survival. [ABSTRACT FROM AUTHOR]

Aim: To Assess the involvement of Peripheral and Central Brainstem Auditory Pathways in Hypertension Patients Materials & Methods: Eligibility Criteria for Hypertension Patients in the Study: BP > 140/90 mmHg, as per JNC 7 Guidelines, and Under Control with Antihypertensive Medications. Subjects with Acute Illness were excluded. Informed Written Consent Acquisition. Informed Written Consent Acquisition in the Study was made to Ensure Ethical Participation. Exclusion Criteria and Instrumentation in the Study: Patients with associated diseases (e.g., Diabetes Mellitus, Ischemic Heart Disease, Cerebrovascular Disease) or auditory abnormalities were excluded. Medicaid Neuroperfect plus Instrument was utilized, and electrodes were placed following the 10-20 international system of EEG electrode placement. The parameters include: 1. Absolute latency of all the waves from I to V 2. Interpeak latency I-III, I-V and III-V Result: The results of the study indicate that the Absolute Latency of Wave I in the hypertensive group showed a statistically significant prolongation, with a P value of 0.0001. This suggests that there is a notable delay in the auditory nerve response in these individuals compared to the control group. The statistically significant prolongation observed in the latency values of Waves I, V, Inter-peak latency I-V, and Inter-peak latency III-V highlights the impact of hypertension on auditory function and warrants further investigation for a better understanding of the underlying mechanisms. Conclusion: Individuals with hypertension show measurable delays in auditory nerve responses and the conduction of auditory signals along brainstem pathways. Further research in this area may enhance understanding of underlying mechanisms and explore innovative approaches to manage auditory abnormalities in hypertensive patients. [ABSTRACT FROM AUTHOR]

Perceptual systems heavily rely on prior knowledge and predictions to make sense of the environment. Predictions can originate from multiple sources of information, including contextual short-term priors, based on isolated temporal situations, and context-independent long-term priors, arising from extended exposure to statistical regularities. While the effects of short-term predictions on auditory perception have been well-documented, how long-term predictions shape early auditory processing is poorly understood. To address this, we recorded magnetoencephalography data from native speakers of two languages with different word orders (Spanish: functor-initial vs Basque: functor-final) listening to simple sequences of binary sounds alternating in duration with occasional omissions. We hypothesized that, together with contextual transition probabilities, the auditory system uses the characteristic prosodic cues (duration) associated with the native language’s word order as an internal model to generate long-term predictions about incoming non-linguistic sounds. Consistent with our hypothesis, we found that the amplitude of the mismatch negativity elicited by sound omissions varied orthogonally depending on the speaker’s linguistic background and was most pronounced in the left auditory cortex. Importantly, listening to binary sounds alternating in pitch instead of duration did not yield group differences, confirming that the above results were driven by the hypothesized long-term ‘duration’ prior. These findings show that experience with a given language can shape a fundamental aspect of human perception – the neural processing of rhythmic sounds – and provides direct evidence for a long-term predictive coding system in the auditory cortex that uses auditory schemes learned over a lifetime to process incoming sound sequences. [ABSTRACT FROM AUTHOR]

AbstractObjectiveDesignStudy sampleResultsConclusionThis study aimed to explore the functional integrity of vestibulo-masseteric and sacculo-collic reflex pathways in individuals with Auditory Neuropathy (AN). The study also aimed at finding the correlation between mVEMP and cVEMP response parameters for AN and healthy individuals.Standard group comparison research designIndividuals with AN (n = 20); age-gender matched healthy individuals (n = 20) were recruited. Each participant underwent routine audiological evaluation; mVEMP and cVEMP testing. mVEMP and cVEMP were recorded using 500 Hz tone burst stimulus for all the participants.Most of the AN individuals had no mVEMP (ipsilateral & contralateral − 60%; bilateral − 50%) and cVEMP (60%) responses. There was no significant association (p > 0.05) between the duration of AN with mVEMP and cVEMP findings. However, a significant correlation (p < 0.05) was found for EMG rectified amplitude of mVEMP and cVEMP in AN.The results of this study suggested an impaired function of the vestibulomassteric and sacculocollic reflex pathways in individuals with AN. Vestibular evaluation should be included as a part of the regular test battery for individuals with AN. [ABSTRACT FROM AUTHOR]

Novel stimulation methods are needed to overcome the limitations of contemporary cochlear implants. Optogenetics is a technique that confers light sensitivity to neurons via the genetic introduction of light-sensitive ion channels. By controlling neural activity with light, auditory neurons can be activated with higher spatial precision. Understanding the behaviour of opsins at high stimulation rates is an important step towards their translation. To elucidate this, we compared the temporal characteristics of auditory nerve and inferior colliculus responses to optogenetic, electrical, and combined optogenetic-electrical stimulation in virally transduced mice expressing one of two channelrhodopsins, ChR2-H134R or ChIEF, at stimulation rates up to 400 pulses per second (pps). At 100 pps, optogenetic responses in ChIEF mice demonstrated higher fidelity, less change in latency, and greater response stability compared to responses in ChR2-H134R mice, but not at higher rates. Combined stimulation improved the response characteristics in both cohorts at 400 pps, although there was no consistent facilitation of electrical responses. Despite these results, day-long stimulation (up to 13 h) led to severe and non-recoverable deterioration of the optogenetic responses. The results of this study have significant implications for the translation of optogenetic-only and combined stimulation techniques for hearing loss. [ABSTRACT FROM AUTHOR]

Key points Along the ascending auditory pathway, there is a broad shift from temporal coding, which is common in the lower auditory brainstem, to rate coding, which predominates in auditory cortex. This temporal‐to‐rate transition is particularly prominent in the inferior colliculus (IC), the midbrain hub of the auditory system, but the mechanisms that govern how individual IC neurons integrate information across time remain largely unknown. Here, we report the widespread expression of Glun2c and Glun2d mRNA in IC neurons. GluN2C/D‐containing NMDA receptors are relatively insensitive to voltage‐dependent Mg2+ blockade, and thus can conduct current at resting membrane potential. Using in situ hybridization and pharmacology, we show that vasoactive intestinal peptide neurons in the IC express GluN2D‐containing NMDA receptors that are activatable by commissural inputs from the contralateral IC. In addition, GluN2C/D‐containing receptors have much slower kinetics than other NMDA receptors, and we found that GluN2D‐containing receptors facilitate temporal summation of synaptic inputs in vasoactive intestinal peptide neurons. In a model neuron, we show that a GluN2C/D‐like conductance interacts with the passive membrane properties of the neuron to alter temporal and rate coding of stimulus trains. Consistent with this, we show in vivo that blocking GluN2C/D‐containing receptors decreases both the spontaneous firing rate and the overall firing rate elicited by amplitude‐modulated sounds in many IC neurons. These results suggest that GluN2C/D‐containing NMDA receptors influence rate coding for auditory stimuli in the IC by facilitating the temporal integration of synaptic inputs. NMDA receptors are critical components of most glutamatergic circuits in the brain, and the diversity of NMDA receptor subtypes yields receptors with a variety of functions. We found that many neurons in the auditory midbrain express GluN2C and/or GluN2D NMDA receptor subunits, which are less sensitive to Mg2+ blockade than the more commonly expressed GluN2A/B subunits. We show that GluN2C/D‐containing receptors conducted current at resting membrane potential and enhanced temporal summation of synaptic inputs. In a model, we show that GluN2C/D‐containing receptors provide additive gain for input‐output functions driven by trains of synaptic inputs. In line with this, we found that blocking GluN2C/D‐containing NMDA receptors in vivo decreased both spontaneous firing rates and firing evoked by amplitude‐modulated sounds. [ABSTRACT FROM AUTHOR]

IntroductionMethodsResultsConclusionsDiagnosis, assessment, and management of sports-related concussion require a multi-modal approach. Yet, currently, an objective assessment of auditory processing is not included. The auditory system is uniquely complex, relying on exquisite temporal precision to integrate signals across many synapses, connected by long axons. Given this complexity and precision, together with the fact that axons are highly susceptible to damage from mechanical force, we hypothesize that auditory processing is susceptible to concussive injury.We measured the frequency-following response (FFR), a scalp-recorded evoked potential that assesses processing of complex sound features, including pitch and phonetic identity. FFRs were obtained on male Division I Collegiate football players prior to contact practice to determine a pre-season baseline of auditory processing abilities, and again after sustaining a sports-related concussion. We predicted that concussion would decrease pitch and phonetic processing relative to the student-athlete’s preseason baseline.We found that pitch and phonetic encoding was smaller post-concussion. Student-athletes who sustained a second concussion showed similar declines after each injury.Auditory processing should be included in the multimodal assessment of sports-related concussion. Future studies that extend this work to other sports, other injuries (e.g. blast exposure), and to female athletes are needed. [ABSTRACT FROM AUTHOR]

Introduction "Good hearing" (DoDI 6030.03 6.5&6.6) is a combat multiplier, critical to service members' lethality and survivability on the battlefield. Exposure to an explosive blast or high-intensity continuous noise is common in operational settings with the potential to compromise both hearing and vestibular health and jeopardize safety and high-level mission performance. The Joint Trauma System Acoustic Trauma Clinical Practice Guideline was published in 2018, providing recommendations for the assessment and treatment of aural blast injuries and acoustic trauma in the forward deployed environment. Combat care capabilities responsive to current threat environments emphasize prolonged casualty care. Despite recommendations, auditory system health has not been assessed routinely or in its entirety on the battlefield. This is due primarily to the large footprint of an audiometric booth and to the heavy logistical burden of providing high-quality, comprehensive auditory system (including vestibular) examinations in the combat environment. Materials and Methods The Defense Health Agency Hearing Center of Excellence has completed a Doctrine, Organization, Training, Materiel, Leadership & Education, Personnel, Facilities, and Policy (DOTmLPF-P) analysis of battlefield auditory system assessment and treatment, using 67 existing DoD documents and artifacts related to operational medicine. Results Our analysis found that acoustic trauma is generally not addressed in any of the DOTmLPF-P domains. We recommend that auditory system assessment and treatment be incorporated across the continuum of care on the battlefield. This should be addressed through Prolonged Field Care and Tactical Combat Casualty Care guidance and in all Tactical Combat Casualty Care training programs. Equipment sets should be modified to include boothless technology and associated materiel for auditory system assessment. Policy and Doctrine changes would be required to mandate and support the implementation of these services. Uniformed audiologists should be added to the organizational structure at role 3 or higher to provide direct patient care; consult with other health care providers and commanders; develop and support enforcement of noise hazard guidelines; track hearing readiness; and, when necessary, provide specialized hearing protection devices that can compensate for hearing loss. Conclusions These recommendations aim to help the DoD bring about necessary assessments and interventions for acoustic trauma so that service members can have better hearing outcomes and maintain critical auditory system function on the battlefield. [ABSTRACT FROM AUTHOR]

We studied the function of the auditory system in Wistar rats after repeated intravenous administration of nicotinamide riboside (NR). The functional activity of the receptor and retrocochlear parts of the auditory system were assessed by recording short-latency auditory evoked potentials (SLAEPs) and distortion-product otoacoustic emissions (DPOAEs) at baseline, immediately after NR administration, and 1 and 2 months later. Repeated intravenous NR administration (cumulative dose of 2700 mg/kg) to Wistar rats has a detrimental impact on the structures within the cochlear section of the auditory system. [ABSTRACT FROM AUTHOR]

The tympanic middle ear (TME) is a complex morphological adaptation that facilitates auditory reception in multiple clades of tetrapods, including anurans. Despite its utility, it has been partially or completely lost at least 38 times in anurans, and there is no clear explanation for how or why this loss occurred. We used micro-CT scans and 3D segmentation to catalog presence/absence and shape of the columella throughout the Central American toad genus Incilius. We found that the TME has been lost multiple times in Incilius and our outgroup Rhinella, with at least one regaining event. Absence of the columella and the different shapes of the columella both have high phylogenetic signal. Incilius species have a different distribution of columella shapes than many other genera of anurans that have been surveyed, including more blade-shaped columellae than found in other genera and one species with vestigial remnants of a columella. The columella shape most common in Incilius, a blade, may be derived from the rod shape also found in many other bufonids; the adaptive significance of this trait remains unknown. This study succeeds in providing a fine-scale review of earlessness and columellar morphology in Incilius, but the processes underlying the patterns we observe remain unclear. [ABSTRACT FROM AUTHOR]

Altered sensory processing especially in the auditory system is considered a typical observation in children with autism spectrum disorder (ASD). Auditory temporal processing is known to be impaired in ASD children. Although research suggests that auditory temporal processing abnormalities could be responsible for the core aspects of ASD, few studies have examined early time processing and their results have been conflicting. The present event-related potential (ERP) study investigated the early neural responses to duration and inter-stimulus interval (ISI) deviants in nonspeech contexts in children with ASD and a control group of typically developing (TD) children matched in terms of age and IQ. A passive auditory oddball paradigm was employed to elicit the mismatch negativity (MMN) for change detection considering both the duration and ISI-based stimulus. The MMN results showed that the ASD group had a relatively diminished amplitude and significant delayed latency in response to duration deviants. The findings are finally discussed in terms of hyper-hyposensitivity of auditory processing and the fact that the observed patterns may potentially act as risk factors for ASD development within the research domain criteria (RDoC) framework. [ABSTRACT FROM AUTHOR]

A speech intelligibility (SI) prediction model is proposed that includes an auditory preprocessing component based on the physiological anatomy and activity of the human ear, a hierarchical spiking neural network, and a decision back-end processing based on correlation analysis. The auditory preprocessing component effectively captures advanced physiological details of the auditory system, such as retrograde traveling waves, longitudinal coupling, and cochlear nonlinearity. The ability of the model to predict data from normal-hearing listeners under various additive noise conditions was considered. The predictions closely matched the experimental test data under all conditions. Furthermore, we developed a lumped mass model of a McGee stainless-steel piston with the middle-ear to study the recovery of individuals with otosclerosis. We show that the proposed SI model accurately simulates the effect of middle-ear intervention on SI. Consequently, the model establishes a model-based relationship between objective measures of human ear damage, like distortion product otoacoustic emissions, and speech perception. Moreover, the SI model can serve as a robust tool for optimizing parameters and for preoperative assessment of artificial stimuli, providing a valuable reference for clinical treatments of conductive hearing loss. [ABSTRACT FROM AUTHOR]

Listeners exhibit varying levels of tolerance for background noise during speech communication. It has been proposed that low tolerance of background noise may be the consequence of abnormally amplified gain in the central auditory system (CAS). Here, using a dataset of young adults with normal hearing thresholds, we asked whether central gain mechanisms might also explain cases of hypertolerance of background noise, as well as cases of reduced, but not abnormal, tolerance. We used the auditory brainstem response to derive a measure of CAS gain (wave V/wave I ratio) to compare listeners' background noise tolerance while listening to speech, grouping them into three categories: hyper, high, and medium tolerance. We found that hypertolerant listeners had reduced CAS gain compared to those with high tolerance. This effect was driven by wave V not wave I. In addition, the medium tolerant listeners trended toward having reduced wave I and reduced wave V amplitudes and generally higher levels of exposure to loud sound, suggestive of the early stages of noise-compromised peripheral function without an apparent compensatory increase in central gain. Our results provide physiological evidence that 1) reduced CAS gain may account for hypertolerance of background noise but that 2) increased CAS gain is not a prerequisite for medium tolerance of background noise. NEW & NOTEWORTHY: Our findings strengthen the proposed mechanistic connection between background noise tolerance and auditory physiology by suggesting a link between hypertolerance and reduced central auditory gain, measured by the auditory brainstem response. [ABSTRACT FROM AUTHOR]

Background: Sensorineural hearing loss (SNHL) in children could impact speech processing along different levels of the auditory pathway; subcortical and cortical. The most frequently used psychoacoustic tests for temporal resolution and ordering evaluation are Gaps-In-Noise (GIN) and Pitch Pattern Sequence (PPS) tests. Moreover, speech-evoked auditory brainstem response (speech-ABR) represents an electrophysiologic test of brainstem speech processing. Aim: To study the impact of mild to moderate SNHL on speech neural encoding in school-aged children, using psychoacoustic (GIN and PPS) and electrophysiological (speech-ABR) tests and to estimate the accuracy of the psychoacoustic and electrophysiological tests in the diagnosis of temporal processing deficit. Methods: This observational, case-control study involved 30 school-aged children who were classified into; control group of normal-hearing children and study group of 20 children with mild to moderate SNHL. They were subjected to history-data reporting, basic audiological testing, and both psychoacoustic and electrophysiologic evaluation of the temporal auditory processing. Results: In comparison to the control group, there were significantly higher approximate threshold (APT) measure of GIN test in the moderate SNHL subgroups, lower total correct score measure of GIN test at a lower (mild) degree of SNHL, lower PPS scores as the hearing threshold increased above normal, and longer speech-ABR latency in the moderate SNHL subgroup. All the examined measures revealed a high accuracy with the APT measure of the GIN test showing the highest accuracy (92%). Conclusions: The psychoacoustic and electrophysiologic evaluation provided evidence of temporal auditory processing impairment in children with SNHL. [ABSTRACT FROM AUTHOR]

Background: Cochlear implant (CI) electrode insertion can change the mechanical state of the ear whereby wideband tympanometry absorbance (WBTA) may serve as a sensitive tool to monitor these mechanical changes of the peripheral auditory pathway after CI surgery. In WBTA, the amount of acoustic energy reflected by the tympanic membrane is assessed over a wide frequency range from 226 Hz to 8000 Hz. The objective of this study was to monitor changes in WBTA in CI recipients before and after surgery. Methods: Following otoscopy, WBTA measurements were conducted twice in both ears of 38 standard CI recipients before and in the range of 4 to 15 weeks after CI implantation. Changes from pre- to postoperative absorbance patterns were compared for the implanted as well as the contralateral control ear for six different frequencies (500 Hz, 750 Hz, 1000 Hz, 2000 Hz, 3000 Hz, 4000 Hz). Furthermore, the influence of the time point of the measurement, surgical access, electrode type, sex and side of the implantation were assessed for the implanted and the control ear in a linear mixed model. Results: A significant decrease in WBTA could be observed in the implanted ear when compared with the contralateral control ear for 750 Hz (p < 0.01) and 1000 Hz (p < 0.05). The typical two-peak pattern of WBTA measurements was seen in both ears preoperatively but changed to a one-peak pattern in the newly implanted ear. The linear mixed model showed that not only the cochlear implantation in general but also the insertion through the round window compared to the cochleostomy leads to a decreased absorbance at 750 and 1000 Hz. Conclusions: With WBTA, we were able to detect mechanical changes of the acoustical pathway after CI surgery. The implantation of a CI led to decreased absorbance in the lower frequencies and the two-peak pattern was shifted to a one-peak pattern. The result of the linear mixed model indicates that WBTA can detect mechanical changes due to cochlear implantation not only in the middle ear but also in the inner ear. [ABSTRACT FROM AUTHOR]

Purpose: This study focused on the selected markers of oxidative stress, impact of elevated lead levels on long-term hearing quality. We investigated whether the presence of certain essential minerals might provide protection to the auditory system against the effects of lead (and cadmium) compounds. Methods: The research group included 280 male employees of the zinc and lead smelter, which was divided into: L-Pb—low blood lead concentration (PbB) subgroup, H-Pb—high PbB subgroup. Hearing tests were performed using the click evoked otoacoustic emission (CEOAE). Results: Zinc protoporphyrin level was significantly higher in the H-Pb subgroup by 68%. Cd concentration was significantly higher in H-Pb by 33%. The Ca concentration was significantly lower in the H-Pb by − 2%. Selected oxidative stress markers concentration were significantly higher in the H-Pb group: malondialdehyde (MDA) by 4%, and lipofuscin (LPS) by 9%. In the CEOAE results showed statistically significant differences between the L-Pb and H-Pb subgroups. Larger negative changes in otoemission amplitude were observed in H-Pb subgroup. All otoemission results showed a statistically significant negative correlation with age, time of work, MDA concentration, and with PbB. Selected CEOAE parameters showed a significant negative correlation with cadmium blood concentration (CdB), and a positive correlation with Ca and Zn. Conclusion: Elevated blood lead content in occupational exposure is associated with an increase in MDA and LPS concentration, which negatively correlates with CEOAE parameters. This suggests an important role of oxidative stress in the long-term deterioration of hearing. [ABSTRACT FROM AUTHOR]

The matched filter hypothesis proposes a close match between senders and receivers and is supported by several studies on variation in signal properties and sensory-processing mechanisms among species and populations. Importantly, within populations, individual variation in sensory processing may affect how receivers perceive signals. Our main goals were to characterize hearing sensitivity of Pacific treefrogs (Pseudacris regilla), assess patterns of individual variation in hearing sensitivity, and evaluate how among-individual variation in hearing sensitivity and call frequency content affect auditory processing of communication signals. Overall, males and females are most sensitive to frequencies between 2.0 and 2.5 kHz, which matches the dominant frequency of the call, and have a second region of high sensitivity between 400 and 800 Hz that does not match the fundamental frequency of the call. We found high levels of among-individual variation in hearing sensitivity, primarily driven by subject size. Importantly, patterns of among-individual variation in hearing differ between males and females. Cross-correlation analyses reveal that among-individual variation in hearing sensitivity may lead to differences on how receivers, particularly females, perceive male calls. Our results suggest that individual variation in sensory processing may affect signal perception and influence the evolution of sexually selected traits. [ABSTRACT FROM AUTHOR]

Short-latency auditory-evoked potentials (AEPs) were recorded non-invasively in the bottlenose dolphin Tursiops truncatus. The stimuli were two sound clicks that were played either monaurally (both clicks to one and the same acoustic window) or dichotically (the leading stimulus (masker) to one acoustic window and the delayed stimulus (test) to the other window). The ratio of the levels of the two stimuli was 0, 10, or 20 dB (at 10 and 20 dB, the leading stimulus was of a higher level). The inter-stimulus intervals (ISIs) varied from 0.15 to 10 ms. The test response magnitude was assessed by correlation analysis as a percentage of the control (non-masked) response. At monaural stimulation, the test response was of a constant magnitude (5–6% of the control) at ISIs of 0.15–0.3 ms and recovered at longer ISIs. At dichotic stimulation, the deepest suppression of the test response occurred at ISIs of 0.5–0.7 ms. The response was slightly suppressed at short ISIs (0.15–0.3 ms) and recovered at ISIs longer than 0.5–0.7 ms. The relation of parameters of the forward masking to echolocation in dolphins is discussed. [ABSTRACT FROM AUTHOR]

Sound‐source localization is based on spatial cues arising due to interactions of sound waves with the torso, head and ears. Here, we evaluated neural responses to free‐field sound sources in the central nucleus of the inferior colliculus (CIC), the medial geniculate body (MGB) and the primary auditory cortex (A1) of Mongolian gerbils. Using silicon probes we recorded from anaesthetized gerbils positioned in the centre of a sound‐attenuating, anechoic chamber. We measured rate‐azimuth functions (RAFs) with broad‐band noise of varying levels presented from loudspeakers spanning 210° in azimuth and characterized RAFs by calculating spatial centroids, Equivalent Rectangular Receptive Fields (ERRFs), steepest slope locations and spatial‐separation thresholds. To compare neuronal responses with behavioural discrimination thresholds from the literature we performed a neurometric analysis based on signal‐detection theory. All structures demonstrated heterogeneous spatial tuning with a clear dominance of contralateral tuning. However, the relative amount of contralateral tuning decreased from the CIC to A1. In all three structures spatial tuning broadened with increasing sound‐level. This effect was strongest in CIC and weakest in A1. Neurometric spatial‐separation thresholds compared well with behavioural discrimination thresholds for locations directly in front of the animal. Our findings contrast with those reported for another rodent, the rat, which exhibits homogenous and sharply delimited contralateral spatial tuning. Spatial tuning in gerbils resembles more closely the tuning reported in A1 of cats, ferrets and non‐human primates. Interestingly, gerbils, in contrast to rats, share good low‐frequency hearing with carnivores and non‐human primates, which may account for the observed spatial tuning properties. [ABSTRACT FROM AUTHOR]

Infants begin to segment word forms from fluent speech—a crucial task in lexical processing—between 4 and 7 months of age. Prior work has established that infants rely on a variety of cues available in the speech signal (i.e., prosodic, statistical, acoustic‐segmental, and lexical) to accomplish this task. In two experiments with French‐learning 6‐ and 10‐month‐olds, we use a psychoacoustic approach to examine if and how degradation of the two fundamental acoustic components extracted from speech by the auditory system, namely, temporal (both frequency and amplitude modulation) and spectral information, impact word form segmentation. Infants were familiarized with passages containing target words, in which frequency modulation (FM) information was replaced with pure tones using a vocoder, while amplitude modulation (AM) was preserved in either 8 or 16 spectral bands. Infants were then tested on their recognition of the target versus novel control words. While the 6‐month‐olds were unable to segment in either condition, the 10‐month‐olds succeeded, although only in the 16 spectral band condition. These findings suggest that 6‐month‐olds need FM temporal cues for speech segmentation while 10‐month‐olds do not, although they need the AM cues to be presented in enough spectral bands (i.e., 16). This developmental change observed in infants' sensitivity to spectrotemporal cues likely results from an increase in the range of available segmentation procedures, and/or shift from a vowel to a consonant bias in lexical processing between the two ages, as vowels are more affected by our acoustic manipulations. Research Highlights: Although segmenting speech into word forms is crucial for lexical acquisition, the acoustic information that infants' auditory system extracts to process continuous speech remains unknown.We examined infants' sensitivity to spectrotemporal cues in speech segmentation using vocoded speech, and revealed a developmental change between 6 and 10 months of age.We showed that FM information, that is, the fast temporal modulations of speech, is necessary for 6‐ but not 10‐month‐old infants to segment word forms.Moreover, reducing the number of spectral bands impacts 10‐month‐olds' segmentation abilities, who succeed when 16 bands are preserved, but fail with 8 bands. [ABSTRACT FROM AUTHOR]

Infants are immersed in a world of sounds from the moment their auditory system becomes functional, and experience with the auditory world shapes how their brain processes sounds in their environment. Across cultures, speech and music are two dominant auditory signals in infants' daily lives. Decades of research have repeatedly shown that both quantity and quality of speech input play critical roles in infant language development. Less is known about the music input infants receive in their environment. This study is the first to compare music input to speech input across infancy by analyzing a longitudinal dataset of daylong audio recordings collected in English‐learning infants' home environments, at 6, 10, 14, 18, and 24 months of age. Using a crowdsourcing approach, 643 naïve listeners annotated 12,000 short snippets (10 s) randomly sampled from the recordings using Zooniverse, an online citizen‐science platform. Results show that infants overall receive significantly more speech input than music input and the gap widens as the infants get older. At every age point, infants were exposed to more music from an electronic device than an in‐person source; this pattern was reversed for speech. The percentage of input intended for infants remained the same over time for music while that percentage significantly increased for speech. We propose possible explanations for the limited music input compared to speech input observed in the present (North American) dataset and discuss future directions. We also discuss the opportunities and caveats in using a crowdsourcing approach to analyze large audio datasets. A video abstract of this article can be viewed at https://youtu.be/lFj%5fsEaBMN4 Research Highlights: This study is the first to compare music input to speech input in infants' natural home environment across infancy.We utilized a crowdsourcing approach to annotate a longitudinal dataset of daylong audio recordings collected in North American home environments.Our main results show that infants overall receive significantly more speech input than music input. This gap widens as the infants get older.Our results also showed that the music input was largely from electronic devices and not intended for the infants, a pattern opposite to speech input. [ABSTRACT FROM AUTHOR]

Auditory scene analysis (ASA) is the process through which the auditory system makes sense of complex acoustic environments by organising sound mixtures into meaningful events and streams. Although music psychology has acknowledged the fundamental role of ASA in shaping music perception, no efficient test to quantify listeners' ASA abilities in realistic musical scenarios has yet been published. This study presents a new tool for testing ASA abilities in the context of music, suitable for both normal-hearing (NH) and hearing-impaired (HI) individuals: the adaptive Musical Scene Analysis (MSA) test. The test uses a simple 'yes–no' task paradigm to determine whether the sound from a single target instrument is heard in a mixture of popular music. During the online calibration phase, 525 NH and 131 HI listeners were recruited. The level ratio between the target instrument and the mixture, choice of target instrument, and number of instruments in the mixture were found to be important factors affecting item difficulty, whereas the influence of the stereo width (induced by inter-aural level differences) only had a minor effect. Based on a Bayesian logistic mixed-effects model, an adaptive version of the MSA test was developed. In a subsequent validation experiment with 74 listeners (20 HI), MSA scores showed acceptable test–retest reliability and moderate correlations with other music-related tests, pure-tone-average audiograms, age, musical sophistication, and working memory capacities. The MSA test is a user-friendly and efficient open-source tool for evaluating musical ASA abilities and is suitable for profiling the effects of hearing impairment on music perception. [ABSTRACT FROM AUTHOR]

Introduction: Auditory scene analysis refers to the system through which the auditory system distinguishes distinct auditory events and sources to create meaningful auditory information. The exact number of directly perceived auditory stimuli is unknown, studies suggest it may range from 3 to 5. This number differs among individuals, and potentially may indirectly indicate the ability to store and process the complex information, related to the memory load, which is combined with human cognitive processes. Aim: This study aims to further identify and quantify the number of sounds that can be perceived simultaneously in a complex auditory environment. Material and methods: Participants were presented with structured acoustic recordings and were asked to identify the exact number of targeted stimuli heard throughout the test. The experiment was designed to assess the auditory load and determine the maximum number of auditory stimuli that a healthy human can perceive at once. Results: Our study showed that on average, participants could identify up to three sounds at once with accuracy of responses declining progressively for four sounds or more. Conclusions: This study aimed to investigate the human capacity to detect and identify multiple sound signals simultaneously in a noisy environment. By understanding this ability, we sought to assess cognitive reserve in individuals. Our objective was to determine if auditory load could serve as a diagnostic tool for cognitive evaluation. We believe that further research will establish the validity of this approach, and we anticipate that it is only a matter of time before it becomes a viable method for assessing cognitive function. [ABSTRACT FROM AUTHOR]

The numerical sense of animals includes identifying the numerosity of a sequence of events that occur with specific intervals, e.g., notes in a call or bar of music. Across nervous systems, the temporal patterning of spikes can code these events, but how this information is decoded (counted) remains elusive. In the anuran auditory system, temporal information of this type is decoded in the midbrain, where "interval-counting" neurons spike only after at least a threshold number of sound pulses have occurred with specific timing. We show that this decoding process, i.e., interval counting, arises from integrating phasic, onset-type and offset inhibition with excitation that augments across successive intervals, possibly due to a progressive decrease in "shunting" effects of inhibition. Because these physiological properties are ubiquitous within and across central nervous systems, interval counting may be a general mechanism for decoding diverse information coded/encoded in temporal patterns of spikes, including "bursts," and estimating elapsed time. [ABSTRACT FROM AUTHOR]

The physiological interactions between the peripheral and central auditory systems are crucial for auditory information transmission and perception, while reliable models for auditory neural circuits are currently lacking. To address this issue, mouse and human neural pathways are generated by utilizing a carbon nanotube nanofiber system. The super‐aligned pattern of the scaffold renders the axons of the bipolar and multipolar neurons extending in a parallel direction. In addition, the electrical conductivity of the scaffold maintains the electrophysiological activity of the primary mouse auditory neurons. The mouse and human primary neurons from peripheral and central auditory units in the system are then co‐cultured and showed that the two kinds of neurons form synaptic connections. Moreover, neural progenitor cells of the cochlea and auditory cortex are derived from human embryos to generate region‐specific organoids and these organoids are assembled in the nanofiber‐combined 3D system. Using optogenetic stimulation, calcium imaging, and electrophysiological recording, it is revealed that functional synaptic connections are formed between peripheral neurons and central neurons, as evidenced by calcium spiking and postsynaptic currents. The auditory circuit model will enable the study of the auditory neural pathway and advance the search for treatment strategies for disorders of neuronal connectivity in sensorineural hearing loss. [ABSTRACT FROM AUTHOR]

This study investigates the effectiveness of photobiomodulation therapy (PBMT) in treating chronic high-frequency tinnitus with the TINI device, a near-infrared (830 nm) laser. The study includes preliminary animal experiments with 28 mice and a randomized controlled trial with 56 participants to examine the functional and molecular changes in the auditory system that PBMT may cause. The animal model used sodium salicylate to induce tinnitus, followed by PBMT, which showed promising reductions in the behavioral evidence of tinnitus and a reversal of tinnitus-associated upregulation of vesicular glutamate transporters 2 expression in the ipsilateral dorsal cochlear nucleus (p < 0.05). In the clinical trial, participants with chronic high-frequency tinnitus received trans-tympanic application of the TINI device. The results did not show a significant difference in tinnitus score at the final time point when compared to the sham group. However, questionnaires revealed significant improvements in tinnitus symptoms and psychological outcomes following treatment with the TINI device compared to before treatment (p < 0.05). These findings suggest that while PBMT has potential benefits, its clinical effectiveness may be unclear due to its complex nature and interaction with other conditions. Further research is required to optimize treatment parameters and gain a complete understanding of the therapeutic potential of PBMT in managing tinnitus. [ABSTRACT FROM AUTHOR]

Categorical sensory representations are critical for many behaviors, including speech perception. In the auditory system, categorical information is thought to arise hierarchically, becoming increasingly prominent in higher-order cortical regions. The neural mechanisms that support this robust and flexible computation remain poorly understood. Here, we studied sound representations in the ferret primary and non-primary auditory cortex while animals engaged in a challenging sound discrimination task. Population-level decoding of simultaneously recorded single neurons revealed that task engagement caused categorical sound representations to emerge in non-primary auditory cortex. In primary auditory cortex, task engagement caused a general enhancement of sound decoding that was not specific to task-relevant categories. These findings are consistent with mixed selectivity models of neural disentanglement, in which early sensory regions build an overcomplete representation of the world and allow neurons in downstream brain regions to flexibly and selectively read out behaviorally relevant, categorical information. [ABSTRACT FROM AUTHOR]

AbstractObjectivesDesignStudy SampleResultsConclusionsStandard diagnostic measures focus on threshold elevation but hearing concerns may occur independently of threshold elevation – referred to as “hidden hearing loss” (HHL). A deeper understanding of HHL requires measurements that locate dysfunction along the auditory pathway. This study aimed to describe the relationship and interdependence between certain behavioural and physiological measures of auditory function that are thought to be indicative of HHL.Data were collected on a battery of behavioural and physiological measures of hearing. Threshold-dependent variance was removed from each measure prior to generating a multiple regression model of the behavioural measures using the physiological measures.224 adults in the United States with audiometric thresholds ≤65 dB HL.Thresholds accounted for between 21 and 60% of the variance in our behavioural measures and 5–51% in our physiological measures of hearing. There was no evidence that the behavioural measures of hearing could be predicted by the selected physiological measures.Several proposed behavioural measures for HHL: thresholds-in-noise, frequency-modulation detection, and speech recognition in difficult listening conditions, are influenced by hearing sensitivity and are not predicted by outer hair cell or auditory nerve physiology. Therefore, these measures may not be able to assess threshold-independent hearing disorders. [ABSTRACT FROM AUTHOR]

Background/Objectives: Cognitive impairment in spinocerebellar ataxia patients has been reported since the early-disease stage. We aimed to assess cognitive differences in SCA1 and SCA2 patients. Methods: We performed neuropsychological (NPS) and neurophysiological (auditory event-related potentials, aERPs) assessments in 16 SCA1 and 18 SCA2 consecutive patients. Furthermore, clinical information (age at onset, disease duration, motor disability) was collected. Results: NPS tests yielded scores in the normal range in both groups but with lower scores in the Frontal Assessment Battery (p < 0.05) and Visual Analogue Test for Anosognosia for motor impairment (p < 0.05) in SCA1, and the Trail Making Test (p < 0.01), Raven's progressive matrices (p < 0.01), Stroop (p < 0.05), and emotion attribution tests (p < 0.05) in SCA2. aERPs showed lower N100 amplitude (p < 0.01) and prolonged N200 latency (p < 0.01) in SCA1 compared with SCA2. Clinically, SCA2 had more severe motor disability than SCA1 in the Assessment and Rating of Ataxia Scale. Conclusions: SCA2 showed more significant difficulties in attentional, visuospatial, and emotional function, and greater motor impairment. In contrast, SCA1 showed less cognitive flexibility/phasic ability, probably affected by a more severe degree of dysarthria. The same group revealed less neural activity during nonconscious attentional processing (N100-N200 data), suggesting greater involvement of sensory pathways in discriminating auditory stimuli. NFS did not correlate with NPS findings, implying an independent relationship. However, the specific role of the cerebellum and cerebellar symptoms in NPS test results deserves more focus. [ABSTRACT FROM AUTHOR]

Background: Hearing loss is known to be a serious issue that impedes human communication. The World Health Organization (WHO) estimates that approximately 20 in 100,000 newborns demonstrate congenital hearing impairments, leading to severely impacted language, academic, and social abilities of these children. Objective: The reduced quality of life and work productivity among hearing-impaired individuals eventually affects societal outcomes and development. Since limited studies address the nature of hearing-impaired individuals in Jordan, this research aimed to define the prevalence and nature of hearing loss in Jordan, highlighting important facts about hearing loss epidemiology across Jordanians. Methods: The current research focused on assessing hearing function for 1000 individuals over 12 years to define the rate, most prominent configurations, and the most common characteristics of hearing difficulties in Jordan. Results: The results showed that sixty-three per 1,000 people have hearing loss, most frequently sensorineural hearing loss. The age range of people with hearing loss was 12 to 89 years old, with a median age of 51. The incidence of hearing loss appeared at a later age (33.33%, X2 = 15.74, p<0.05). The percentages of hearing loss were similar across the main Jordanian governorates (X2 = 7.14, p>0.05), with sensorineural hearing loss reported to be the most common type of hearing loss (N = 46, 73.00%), and mild is the most frequent severity (N = 25, X2 = 23.58, p<0.05). No statistical variation was reported in the prevalence of hearing loss based on gender. Conclusion: The rate of hearing loss in Jordan is higher than worldwide prevalence, which was assumed to be due to genetic factors impacting the auditory system. These findings will assist in creating effective hearing conservation programs to reasonably prevent or minimize the spread of hearing loss in Jordan. [ABSTRACT FROM AUTHOR]

Presbycusis, or age-related hearing loss, affects both elderly humans and dogs, significantly impairing their social interactions and cognition. In humans, presbycusis involves changes in peripheral and central auditory systems, with central changes potentially occurring independently. While peripheral presbycusis in dogs is well-documented, research on central changes remains limited. Diffusion tensor imaging (DTI) is a useful tool for detecting and quantifying cerebral white matter abnormalities. This study used DTI to explore the central auditory pathway of senior dogs, aiming to enhance our understanding of canine presbycusis. Dogs beyond 75% of their expected lifespan were recruited and screened with brainstem auditory evoked response testing to select dogs without severe peripheral hearing loss. Sixteen dogs meeting the criteria were scanned using a 3 T magnetic resonance scanner. Tract-based spatial statistics was used to analyze the central auditory pathways. A significant negative correlation between fractional lifespan and fractional anisotropy was found in the acoustic radiation, suggesting age-related white matter changes in the central auditory system. These changes, observed in dogs without severe peripheral hearing loss, may contribute to central presbycusis development. [ABSTRACT FROM AUTHOR]

Sexually dimorphic hearing sensitivity has evolved in many vertebrate species, and the sex with a larger body size typically shows more sensitive hearing. However, generalizing this association is controversial. Research on sexually dimorphic hearing sensitivity contributes to an understanding of auditory sense functions, adaptations, and evolution among species. Therefore, the hypothesized association between body size and hearing needs further validation, especially in specific animal groups. In this study, we assessed hearing sensitivity by measuring auditory brainstem responses (ABRs) in both sexes of 3‐year‐old Chinese softshell turtles (Pelodiscus sinensis). In this species, male bodies are larger than those of female, and individuals spend most of their lives in the mud at the bottom of freshwater habitats. We found that for both sexes, the hearing sensitivity bandwidth was 0.2–0.9 kHz. Although males were significantly larger than females, no significant differences in ABR thresholds or latencies were found between males and females at the same stimulus frequency. These results indicate that P. sinensis hearing is only sensitive to low‐frequency (typically <0.9 kHz) sound signals and that sexually dimorphic hearing sensitivity is not a trait that has evolved in P. sinensis. Physiological and environmental reasons may account for P. sinensis acoustic communication via low‐frequency sound signals and the lack of sexually dimorphic hearing sensitivity in these benthic turtles. The results of this study refine our understanding of the adaptation and evolution of the vertebrate auditory system. [ABSTRACT FROM AUTHOR]

The voltage‐gated Kv3.1/KCNC1 channel is abundantly expressed in fast‐spiking principal neurons and GABAergic inhibitory interneurons throughout the ascending auditory pathway and in various brain regions. Inactivating mutations in the KCNC1 gene lead to forms of epilepsy and a decline in the expression of the Kv3.1 channel is involved in age‐related hearing loss. As oxidative stress plays a fundamental role in the pathogenesis of epilepsy and age‐related hearing loss, we hypothesized that an oxidative insult might affect the function of this channel. To verify this hypothesis, the activity and expression of endogenous and ectopic Kv3.1 were measured in models of oxidative stress‐related aging represented by cell lines exposed to 100 mM d‐galactose. In these models, intracellular reactive oxygen species, thiobarbituric acid reactive substances, sulfhydryl groups of cellular proteins, and the activity of catalase and superoxide dismutase were dysregulated, while the current density of Kv3.1 was significantly reduced. Importantly, the antioxidant melatonin reverted all these effects. The reduction of function of Kv3.1 was not determined by direct oxidation of amino acid side chains of the protein channel or reduction of transcript or total protein levels but was linked to reduced trafficking to the cell surface associated with Src phosphorylation as well as metabolic and endoplasmic reticulum stress. The data presented here specify Kv3.1 as a novel target of oxidative stress and suggest that Kv3.1 dysfunction might contribute to age‐related hearing loss and increased prevalence of epilepsy during aging. The pharmacological use of the antioxidant melatonin can be protective in this setting. [ABSTRACT FROM AUTHOR]

The auditory system can selectively attend to the target source in complex environments, the phenomenon known as the "cocktail party" effect. However, the spatiotemporal dynamics of electrophysiological activity associated with auditory selective spatial attention (ASSA) remain largely unexplored. In this study, single‐source and multiple‐source paradigms were designed to simulate different auditory environments, and microstate analysis was introduced to reveal the electrophysiological correlates of ASSA. Furthermore, cortical source analysis was employed to reveal the neural activity regions of these microstates. The results showed that five microstates could explain the spatiotemporal dynamics of ASSA, ranging from MS1 to MS5. Notably, MS2 and MS3 showed significantly lower partial properties in multiple‐source situations than in single‐source situations, whereas MS4 had shorter durations and MS5 longer durations in multiple‐source situations than in single‐source situations. MS1 had insignificant differences between the two situations. Cortical source analysis showed that the activation regions of these microstates initially transferred from the right temporal cortex to the temporal–parietal cortex, and subsequently to the dorsofrontal cortex. Moreover, the neural activity of the single‐source situations was greater than that of the multiple‐source situations in MS2 and MS3, correlating with the N1 and P2 components, with the greatest differences observed in the superior temporal gyrus and inferior parietal lobule. These findings suggest that these specific microstates and their associated activation regions may serve as promising substrates for decoding ASSA in complex environments. [ABSTRACT FROM AUTHOR]

Objective: Hyperacusis, characterized by an abnormal sensitivity to everyday sounds, is a condition associated with subjective distress and physiological changes in the auditory system. Prevalence rates have varied significantly worldwide, emphasizing the need for standardized criteria. This study aimed to determine the prevalence of hyperacusis among high school students in Mysore district and explore gender differences. Methods: A diverse cohort of 597 high school students participated in this cross-sectional study. The Modified Khalfa Hyperacusis Questionnaire assessed hyperacusis symptoms. Demographic data included age, gender, and educational status. A cut-off score of 28 on the questionnaire identified hyperacusis cases. Data were analyzed descriptively. Results: The study revealed a substantial hyperacusis prevalence of 17.25% among high school students in the Mysore district. Out of 103 identified cases, 43.69% were females, and 56.31% were males. These results suggest a potential gender disparity in hyperacusis prevalence. The study's findings highlight the high prevalence of hyperacusis among Indian high school students, emphasizing the need for attention to this issue in adolescent health. Gender differences observed in this study align with previous research, indicating a higher prevalence among males. Conclusions: Hyperacusis is a prevalent condition among Indian high school students, warranting further research on its causes and co-occurrence across different age groups. These findings underscore the significance of addressing hyperacusis as a critical health concern among adolescents and emphasize the need for tailored interventions and increased awareness. [ABSTRACT FROM AUTHOR]

Background: The digit in the noise test is a simple hearing screening tool that can identify hearing loss at the early stage. This screening tool takes less time than traditional pure-tone audiometry. There is a scarcity of hearing health professionals with few resources for carrying out hearing screening on a large scale in India. Hence, a hearing screening tool for the Hindi-speaking population is needed. Aim and Objective: The study aimed to develop and validate the Digit in Noise test in Hindi (DIN-H). Methods: A native Hindi female speaker recorded single digits from 1 to 9 made into triplet combinations, which were binaurally presented to 20 normal hearing subjects having hearing thresholds less than 25 dBHL from 250 to 8000 Hz in the presence of broadband speech-shaped noise. The digit triplets were homogenized using speech intelligibility function for similar difficulty levels across stimuli. The homogenized stimuli were evaluated by obtaining the Speech Recognition Threshold (SRT) of 20 normal hearing subjects. Results: The Mean SRT was − 10.4 and − 11.3 dB before and after homogenization. A strong positive correlation existed between test and retest SRTs (0.78). Mean SRT and slope obtained before and after optimization were comparable to other languages like Korean and English. This test can act as a reliable screening tool for assessing individuals. The test was administered to 106 normal hearing participants. The 95th percentile of the SRT value obtained was − 5.6 dB, which was kept as a cut-off score for the screening test. Conclusion: DIN-H can be used as a screening tool for assessing the integrity of the auditory system on a large scale in less time for the Hindi-speaking population. [ABSTRACT FROM AUTHOR]