Central Auditory Nervous System Research Articles

Characteristics of Speech Auditory Brainstem Response in Preschool Children With Attention-Deficit/Hyperactivity Disorder.

This study aimed to investigate the characteristics of auditory processing (AP) in preschool children with attention-deficit/hyperactivity disorder (ADHD) using the speech auditory brainstem response (speech-ABR), which provides insights into the AP of speech signals in the central auditory nervous system (CANS). A total of 84 preschool children diagnosed with ADHD, aged 4-6 years, were matched with 84 typically developing (TD) children based on gender and age. All children underwent speech-ABR testing, cognitive assessment using the Wechsler Preschool and Primary Scale of Intelligence-Fourth Edition or the Wechsler Intelligence Scale for Children-Fourth Edition, and a continuous performance test. Children with ADHD exhibited significantly longer latencies of speech-ABR waveforms V, A, and D compared to TD children. Multiple linear regression analysis showed that the latencies of speech-ABR waves V, A, and D were affected by the presence of ADHD, but not by the full-scale intelligence quotient. This study revealed that preschool children with ADHD exhibited abnormal AP of speech signals in their CANS. The findings suggest that speech-ABR can be utilized as a reliable measure to evaluate AP ability in this population, as it remains unaffected by cognitive or attentional factors. The transient response (V, A) of speech-ABR was found to be a significant predictor of ADHD in a clinical setting. Early assessment of AP abnormalities via speech-ABR is recommended in preschool-age children to develop targeted interventions for ADHD. https://doi.org/10.23641/asha.26376502.

Cortical auditory evoked potentials in peripheral neuropathy

BackgroundCortical auditory evoked potentials (CAEPs) display both auditory processing and neurological activity in the auditory cortex. The purpose of this research is to evaluate the importance of CAEPs in identifying auditory processing disorders in patients with peripheral neuropathy (PN) in different pathologies. Sixty cases with PN of different pathologies represented the study group which was classified into two subgroups according to the underlying pathology of PN: those with either axonal PN (44 patients) and those with demyelinating PN (16 patients). The current study also included a control group of 40 healthy volunteers who did not have any peripheral or central auditory neurological disorders. CAEPs were recorded in both groups.ResultsThe study group’s CAEP response showed significantly delayed latencies than the control groups. Comparing the two study subgroups revealed that the axonal PN group had significant delayed latencies of N1 and P2 components in comparison to the demyelinating PN group.ConclusionCortical auditory evoked potentials can be used efficiently to diagnosis central auditory processing disorders in patients with PN. CAEP latencies can be employed alone or in conjunction with amplitudes; however, CAEP latencies are more significant than amplitudes for such purpose. Both demyelinating and axonal PN are associated with impaired auditory processing; however, axonal PN patients are more likely to be affected, suggesting that axonal PN has a significantly drastic effect on the central auditory nervous system.

Electrophysiological Characteristics in Pediatric Cochlear Implantation.

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. 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. 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. 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.

Dynamic Spatial Auditory Processing in the Elderly.

One of the most obvious functional effects of aging on the cognitive and processing processes of spatial hearing is the localization problem and the disorder of speech perception in noise. The purpose of the present study is to investigate the performance of dynamic spatial auditory processing in the elderly. This descriptive and analytical study was conducted on 60 young participants aged from18 to 25 years old and 60 elderly participants aged from 60 to 75 old years, using speech, spatial, and qualities of hearing scale (SSQ) questionnaire, binaural masking level difference (BMLD) and dynamic quick speech in noise (DS-QSIN) tests. Comparing the average scores of the tests and the questionnaire using the independent t test showed a significant difference between the two groups (p < 0.001). It was also found that gender had no effect on the results (p > 0.05). Aging is accompanied by different structural and functional changes in the auditory central nervous system, which leads to a decrease in speech perception in challenging listening environments, as well as a decrease in sound localization abilities, due to the reduction of temporal and spectral information. This problem affects the determination of the source of sound and the spatial cognition of the elderly and leads to a disturbance in the awareness of the auditory environment. Therefore, auditory rehabilitation programs can cause the improvement of spatial auditory processing performance and improve speech perception in noise in the elderly.

Auditory neural processing in children living with HIV uncovers underlying central nervous system dysfunction.

Central nervous system (CNS) damage from HIV infection or treatment can lead to developmental delays and poor educational outcomes in children living with HIV (CLWH). Early markers of central nervous system dysfunction are needed to target interventions and prevent life-long disability. The frequency following response (FFR) is an auditory electrophysiology test that can reflect the health of the central nervous system. In this study, we explore whether the FFR reveals auditory central nervous system dysfunction in CLWH. Cross-sectional analysis of an ongoing cohort study. Data were from the child's first visit in the study. The infectious disease center in Dar es Salaam, Tanzania. We collected the FFR from 151 CLWH and 151 HIV-negative children. To evoke the FFR, three speech syllabi (/da/, /ba/, /ga/) were played monaurally to the child's right ear. Response measures included neural timing (peak latencies), strength of frequency encoding (fundamental frequency and first formant amplitude), encoding consistency (inter-response consistency), and encoding precision (stimulus-to-response correlation). CLWH showed smaller first formant amplitudes ( P < 0.0001), weaker inter-response consistencies ( P < 0.0001) and smaller stimulus to response correlations ( P < 0.0001) than FFRs from HIV-negative children. These findings generalized across the three speech stimuli with moderately strong effect sizes (partial η2 ranged from 0.061 to 0.094). The FFR shows auditory central nervous system dysfunction in CLWH. Neural encoding of auditory stimuli was less robust, more variable, and less accurate. As the FFR is a passive and objective test, it may offer an effective way to assess and detect central nervous system function in CLWH.

Effects of Adding Monaural and Binaural Noise to a Dichotic Listening Task.

The Dichotic Digits Test (DDT) evaluates central auditory nervous system (CANS) dysfunction. The DDT is widely used in audiology clinics worldwide because it is clinically efficient and has good sensitivity and specificity for CANS lesions. However, the DDT shows a strong ceiling effect, which can mitigate its ability to detect subtle CANS dysfunction. This study examines the effects of adding monaural and binaural speech-spectrum noise to the DDT in an effort to make the test more taxing to the CANS and thereby reduce the observed ceiling effect. This was an experimental repeated measures study. The participants were 20 adults aged 18-50 years with normal, bilaterally symmetric peripheral hearing sensitivity. Each participant was administered one standard DDT test list (no noise added) and DDT test lists with binaural, monaural right, and monaural left noise added. For each of the noise-added conditions, lists were administered at two different signal-to-noise ratios (SNRs), for a grand total of seven DDT test lists per participant, presented in randomized order. Monaural and binaural noise effects on DDT scoring indices (Right and Left Ear Percent Correct Scores, Combined Total Percent Correct Scores, and Dichotic Difference Scores), as well as noise effects on the Right Ear Advantage (REA) for speech, were examined. Mixed model analyses of variance (ANOVAs) were used to examine fixed effects and interactions of Noise Condition and Ear. Adding noise to the standard DDT systematically reduced Right and Left Ear Percent Correct Scores and Combined Total Percent Correct Scores. Statistically significant differences on all indices were found between monaural and binaural noise-added conditions, suggesting a possible advantage for binaural listening in noise. These findings suggest that adding noise to tests of dichotic listening increases the difficulty of the task, and that further investigation of dichotic listening patterns in noise could potentially lead to more sensitive clinical evaluations of CANS integrity and function.

Identification of Auditory Processing Disorder Based on the Persian Version of Multiple Auditory Processing Assessment in School-aged Children in Arak City, Iran

Background and Objectives: Auditory processing (AP) takes place throughout the central auditory nervous system. Therefore, to correctly assess auditory processing disorder (APD), it is necessary to use a test battery so that each of these tests can evaluate specific auditory skills. Therefore, considering the importance of detecting children with APD, the Persian version of the multiple auditory processing assessment (MAPA-P) was used in the present study. Methods: The study method was descriptive-analytical and cross-sectional. A total of 300 children aged 9-12 years old in equal numbers in both genders and at any age, from 7 primary schools in Arak City, Iran were enrolled. After ensuring the health of children’s peripheral hearing level, to check their central auditory system, the MAPA-P test battery was performed on laptops with headphones. Analysis of variance (ANOVA) and independent t-test were used to analyze the results. The mean scores in each age group were calculated and finally, the prevalence of APD was determined based on the cut-off point of the whole test. Results: The results showed that the mean scores in all 5 tests had a statistically significant difference in different age groups (P&lt;0.0001), and the mean scores increased with age. Also, no significant difference was observed in the scores of any of the 5 tests between the two genders (P&gt;0.05). The prevalence of APD in the school-age population was 5%. Conclusion: According to the valid results of the MAPA model in many studies, the Persian version of this test battery has been introduced as a standardized test battery. In addition to covering the three crucial domains of AP, it can easily be used in a calm classroom using a CD-RAM. The results of the present study showed that 5% of the children were suspected of APD, which was consistent with the results of the other studies.

Benefits of intervention in the Central Auditory Nervous System in individuals with Neurofibromatosis Type 1.

To verify the effectiveness of acoustically controlled auditory training in individuals with Neurofibromatosis Type 1. The sample consisted of individuals with Neurofibromatosis Type 1, randomly distributed into two groups, making up the intervention group: individuals undergoing formal auditory training; and the comparison group: individuals who were not submitted to the intervention. Behavioral assessment of central auditory processing and electrophysiological evaluation, composed by Brainstem Auditory Evoked Potential and Long Latency-P300 Auditory Evoked Potential, were evaluated in three moments of evaluations: initial evaluation, reevaluation and after four months of reevaluation and comparing the performance between the groups. Better performances in central auditory processing were observed after the formal auditory training in the intervention group with significant differences between the evaluations and performance maintenance four months after the end of the training. Significant differences were observed between the groups in the evaluations after the intervention. The electrophysiological evaluation shows unsystematic variation in the short latency potentials and changes in the long latency potentials with the appearance of the P3 wave after the intervention. The behavioral and electrophysiological evaluation in group that was not submitted to the intervention demonstrated that there is no improvement without the intervention, with deterioration of performance. Significant differences were observed in the behavioral and electrophysiological evaluations, in favor of the group submitted to formal auditory training. Formal auditory training is effective in rehabilitation in individuals with Neurofibromatosis Type 1. Neurofibromatosis 1; Hearing Disorders; Auditory Perceptual Disorders; Acoustic Stimulation; Evoked Potentials, Auditory.

Standardization of Latency and Amplitude Values of Short, Middle and Long Latency Auditory Evoked Potentials in Adults.

Introduction Auditory processing refers to the efficiency and effectiveness with which the central auditory nervous system uses auditory information. Middle- and long-latency auditory evoked potentials are objective electrophysiological tests that can complement the diagnosis of alterations involving central auditory processing. Objective To standardize latency and amplitude values for short-, middle-, and long-latency auditory evoked potentials in adults with normal hearing thresholds. Methods This is a cross-sectional study. Thirty-three adults with normal hearing thresholds, without hearing complaints, and with normal central auditory processing were evaluated. All underwent basic audiological evaluation, central auditory processing assessment, and short-, middle-, and long-latency auditory evoked potentials. Results Absolute latency and interpeak values for middle- and long-latency auditory evoked potentials were lower than internationally suggested. However, for the brainstem auditory evoked potential, the means were within the range considered as normal, as suggested in the equipment. Conclusion The present study provided measurements of normal latencies and amplitudes for short-, middle-, and long-latency auditory evoked potentials in adults.

Neuronal Cytoglobin in the Auditory Brainstem of Rat and Mouse: Distribution, Cochlear Projection, and Nitric Oxide Production.

Cytoglobin (Cygb), a hemoprotein of the globin family, is expressed in the supportive tissue cells of the fibroblast lineage and in distinct neuronal cell populations. The expression pattern and regulatory parameters of fibroblasts and related cells were studied in organs such as the kidney and liver in a variety of animal models. In contrast, knowledge about cytoglobin-expressing neurons is sparse. Only a few papers described the distribution in the brain as ubiquitous with a restricted number of neurons in focal regions. Although there is evidence for cytoglobin involvement in neuronal hypoxia tolerance, its presence in the auditory system was not studied despite high metabolism rates and oxygen demands of the cochlea and related brainstem centers. In a continuation of a previous study demonstrating Cygb-neurons in, inter alia, auditory regions of the mouse brain, we concentrated on the superior olivary complex (SOC) in the present study. We sought to investigate the distribution, projection pattern and neurochemistry of Cygb-neurons in the SOC. We conducted immunohistochemistry using a Cygb antibody and found that this brainstem region, functionally competent for bilateral hearing and providing cochlear hair cell innervation, contains a considerable number of Cygb-expressing neurons (averaging 2067 ± 211 making up 10 ±1% percent of total neuron number) in rats, and 514 ± 138 (6 ± 1%) in mice. They were observed in all regions of the SOC. Retrograde neuronal tract tracing with Fluorogold injected into the cochlea demonstrated that 1243 ± 100 (6 ± 1% of total neuron number in rat SOC)) were olivocochlear neurons. Approximately 56% of total Cygb neurons were retrogradely labelled, while the majority of olivocochlear neurons of both lateral and medial systems were Cygb-immunoreactive. We also conducted double immunofluorescence staining for Cygb and neuronal nitric oxide synthase (nNOS), the enzyme responsible for nitric oxide production, and observed that cytoglobin in the SOC frequently co-localized with nNOS. Our findings suggest that cytoglobin plays an important physiologic role in the oxygen homeostasis of the peripheral and central auditory nervous system. Further studies, also including transgenic animal models, are required to shed more light on the function(s) of Cygb in neurons, in particular of the auditory system.

Comparing Auditory Brain Stem Responses and Transient Otoacoustic Emissions in Premature Infants with Auditory Developmental Delay: Evidence of Temporary Auditory Neuropathy.

Premature birth causes some permanent or temporary abnormalities in the hearing system of the newborn. Inadequate development of the central auditory nervous system and balance, as well as the delay in the formation of the nerve myelin, can be the cause of many hearing disorders, including permanent or temporary auditory neuropathy spectrum disorder (ANSD). The present study aims to identify and understand developmental delay disorder in the hearing system of infants and investigate the possibility of temporary auditory neuropathy in infants. In this comparative analytical study, twenty premature infants were randomly selected for hearing tests using auditory brainstem response and transient otoacoustic emissions at the time of discharge and three months after the first evaluation. The different components of these tests were analyzed and compared before and after developing the auditory system. The OAEs test showed a signal-to-noise ratio above six dB with appropriate amplitudes in all infants. The grand average waveform of the ABR showed a significant difference between the amplitudes of waves III and V before and after maturation in both ears (p<0.05). In addition, the absolute latency of waves, specifically III and V, showed a significant difference between the two assessment times (0.05). The present study confirmed the occurrence of temporary ANSD or delayed maturation in premature infants following the lack of complete growth and myelination of auditory nerve fibers. There is a need to determine the hearing status of premature infants by frequent examinations and prevent any unnecessary prescription of amplifications.

Ośrodkowe zaburzenia przetwarzania słuchowego u dzieci w wieku szkolnym w świetle uczenia (się) języka angielskiego

Central auditory processing disorders are defined as deficits in the neural processing of auditory information in the central auditory nervous system with simultaneous normal hearing. Due to the inappropriate reception of speech sounds and difficulties in their understanding and reproduction, pupils may have difficulties in learning language, e.g. in earning and remembering vocabulary and pronouncing words correctly which may cause incorrect communication result or even lack of it. It is also worth mentioning that a great number of parents report difficulties in learning foreign language/languages in their children with central auditory processing disorders, especially English. Additionally, there are few studies discussing the topic of learning and teaching a second language among students with central auditory processing disorders. This paper aims to provide the importance and brief characteristics of central auditory processing disorders, as well as a review of the literature and results of questionnaire (about the foreign language learning difficulties) performed in 16 parents whose children were qualified to the listening training.

Relationship Between Temporal Pattern Perception Test and Mismatch Negativity in Children With Auditory Processing Disorder and Dyslexia.

Mismatch negativity (MMN) is an objective test for assessing auditory function. The central auditory nervous system processes different stimuli in various ways. This can be assessed using MMN elicited with different stimuli in an "oddball" paradigm. This study evaluated temporal ordering skills using MMN with different durations of stimuli. This study aimed to determine the correlation between the results of the behavioral duration pattern test (DPT) with MMN in typically developing children versus children with dyslexia and auditory processing disorder (APD). Subjects and. Two groups of children participated in the study. The experimental group included 16 children with APD and dyslexia who had scored below the age-matched scores in the DPT. The control group consisted of 16 typically developing children with age-matched scores in the DPT. MMN was elicited using the same stimuli (250 ms and 500 ms) as that of the DPT in both groups. MMN latency, MMN amplitude, and area under the curve were measured in both groups. Compared to the control group, children with APD and dyslexia showed increased MMN latency, reduced amplitude, and decreased area under the curve. There was a low correlation (r= -0.293, p<0.05) between MMN latency and DPT scores. The correlation between MMN amplitude and DPT scores was moderate (0.472, p<0.001). Furthermore, a strong correlation (0.536, p<0.001) between area under the curve and DPT scores was demonstrated. MMN amplitude and MMN area under the curve could serve as valid indicators during assessment of temporal ordering in children with APD and dyslexia.

KWESTIONARIUSZ JAKOŚCI ŻYCIA I ODPOWIEDZI PODĄŻAJĄCE ZA CZĘSTOTLIWOŚCIĄ U DWÓCH PACJENTÓW Z DYZARTRIĄ I CHOROBĄ NEURODEGENERACYJNĄ: ANALIZA PRZYPADKU

BackgroundEffective speech production involves a complex system that not only requires planning and motor execution in different speech subsystems, but also depends on the proper functioning of the auditory system. In cases of dysarthria, auditory electrophysiological assessment can be important, since it can help diagnose the underlying neurological disease. The objective of this pilot study was to assess the effectiveness of the frequency-following response (FFR) in monitoring the progress of speech therapy in cases of dysarthria due to neurodegenerative disease. It also sought to gauge changes in the patients’ quality of life using a self-report questionnaire.Case reportTwo individuals with dysarthria were assessed by the FFR and by the questionnaire “Living with Dysarthria” while undergoing a speech therapy rehabilitation program aimed at improving their speech. It was found that the speech therapy brought benefits in terms of quality of life, in line with the FFR responses.ConclusionsThe FFR may be a promising approach to monitoring changes in the central auditory nervous system during speech therapy for dysarthria due to acquired neurodegenerative disease.

No Reduction in the 226-Hz Probe Tone Acoustic Reflex Amplitude Following Severe Inner Hair Cell Loss in Chinchillas.

The relationship between the middle ear acoustic reflex (AR) and inner hair cell (IHC) loss is currently unknown. Given that IHC are believed to convey nearly all acoustic information to the central auditory nervous system, it has been assumed that loss of IHC would significantly impact the AR. To evaluate this relationship, we assessed the presence and amplitude of the AR in chinchillas before and after treatment with carboplatin, an anticancer drug that reliably and selectively destroys IHC in this species. Baseline measures of hearing sensitivity, including auditory brainstem response (ABR) thresholds and distortion product otoacoustic emissions (DPOAE), were assessed and then re-evaluated following carboplatin treatment. Post-carboplatin ABR thresholds and DPOAE were found to be unchanged or slightly elevated; results were consistent with published reports. Our main hypothesis was that loss of IHC would abolish the reflex or significantly reduce its amplitude. Contrary to our hypothesis, the ipsilateral 226-Hz AR continued to be reliably elicited following carboplatin treatment. Post-mortem histological analysis confirmed significant IHC loss (65-85 %), but no measurable loss of outer hair cells (OHCs). Given that loss of IHC alone does not significantly reduce the 226-Hz AR, our results suggest that few IHC are needed to maintain the 226-Hz AR response. These results suggest additional studies are needed to better understand the role of IHC in the reflex arc, present opportunities to further study the reflex pathway, and could change how we use the clinical AR as a potential diagnostic tool for IHC dysfunction, including those related to IHC synaptopathy.

Enhanced Dichotic Listening and Temporal Sequencing Ability in Early-Blind Individuals.

Several studies have reported the better auditory performance of early-blind subjects over sighted subjects. However, few studies have compared the auditory functions of both hemispheres or evaluated interhemispheric transfer and binaural integration in blind individuals. Therefore, we evaluated whether there are differences in dichotic listening, auditory temporal sequencing ability, or speech perception in noise (all of which have been used to diagnose central auditory processing disorder) between early-blind subjects and sighted subjects. The study included 23 early-blind subjects and 22 age-matched sighted subjects. In the dichotic listening test (three-digit pair), the early-blind subjects achieved higher scores than the sighted subjects in the left ear (p = 0.003, Bonferroni’s corrected α = 0.05/6 = 0.008), but not in the right ear, indicating a right ear advantage in sighted subjects (p < 0.001) but not in early-blind subjects. In the frequency patterning test (five tones), the early-blind subjects performed better (both ears in the humming response, but the left ear only in the labeling response) than the sighted subjects (p < 0.008, Bonferroni’s corrected α = 0.05/6 = 0.008). Monosyllable perception in noise tended to be better in early-blind subjects than in sighted subjects at a signal-to-noise ratio of –8 (p = 0.054), the results at signal-to-noise ratios of –4, 0, +4, and +8 did not differ. Acoustic change complex responses to/ba/in babble noise, recorded with electroencephalography, showed a greater N1 peak amplitude at only FC5 electrode under a signal-to-noise ratio of –8 and –4 dB in the early-blind subjects than in the sighted subjects (p = 0.004 and p = 0.003, respectively, Bonferroni’s corrected α = 0.05/5 = 0.01). The results of this study revealed early-blind subjects exhibited some advantages in dichotic listening, and temporal sequencing ability compared to those shown in sighted subjects. These advantages may be attributable to the enhanced activity of the central auditory nervous system, especially the right hemisphere function, and the transfer of auditory information between the two hemispheres.

The Onset-Offset N1-P2 Cortical Auditory Evoked Response in Individuals With High-Frequency Sensorineural Hearing Loss: Responses to High- and Low-Frequency Narrowband Noise.

This study aimed to determine whether onset-offset N1-P2 auditory evoked responses differ in amplitude, latency, and offset-to-onset trough-to-peak N1-P2 amplitude ratios (OOAR) between normal hearing (NH) sensitivity and moderate high-frequency sensorineural hearing loss (HFSNHL) groups when stimuli target regions of peripheral hearing sensitivity where the groups are in the normal range (i.e., 500 Hz) versus where they differ regarding presence of hearing loss (i.e., 4000 Hz). Onset-offset N1-P2 auditory evoked responses were measured from 10 participants with normal hearing sensitivity and seven participants with moderate HFSNHL using 500-Hz and 4000-Hz narrowband noise (NBN) stimuli. Stimuli were 2000 ms with 40-ms rise-fall times presented at 50 dB SL referenced to stimulus behavioral thresholds. Amplitudes and latencies were analyzed for N1 and P2 onset and offset components via repeated measures analysis of variance (ANOVA). OOARs were compared between groups using one-way ANOVA and across stimuli per group using paired samples t tests. Despite dB SPL stimulus presentation differences between groups, there were no significant differences in individual/absolute amplitude and latency waveform components between groups for either stimulus. Derived comparative calculations of OOAR for 4000-Hz NBN were significantly larger (p < .025; NH: .39; HFSNHL: .62) for the group with HFSNHL than the group with NH sensitivity; 500-Hz NBN OOAR did not reach significance. OOARs revealed no significant difference between stimuli for the group with normal hearing sensitivity, with .38 OOAR for both stimuli (p = .961). OOAR comparisons for the HFSNHL group across stimuli were significant (p = .012), with the 4000-Hz NBN OOAR being nearly double the size of the 500-Hz NBN OOAR. OOARs may provide insight to the balance of excitatory and inhibitory neural firing in the central auditory nervous system (CANS). Larger OOARs may be a biomarker of reduced CANS inhibition, perhaps indicative of a homeostatic central auditory gain mechanism.

Auditory Processing Skills in Patients with Multiple Sclerosis

Background and Aim: Multiple sclerosis (MS) is neurological disease of the central nervous system. Central auditory nervous system can also be affected by MS. The present study aimed to evaluate monaural and binaural auditory processing in patients with MS. Methods: This cross-sectional study was conducted on 45 patients with MS and 45 normal peers as controls aged 25–45 years. They underwent a central auditory processing test battery including the Persian versions of Buffalo model questionnaire (BMQ), staggered spondee word (SSW) test, quick speech in noise test (QSIN), phonemic synthesis test (PST), and two- pair dichotic digit test (DDT). Results: The results of SSW test, QSIN test, PST, DDT and BMQ in the MS group were significantly different than in the control group (p≤0.001). The results showed the poor performance of patients compared to controls in some monaural and binaural auditory processing skills. Conclusion: Central auditory processing disorder is common among patients with MS. The BMQ is a suitable screening tool for identifying affected people. Dichotic listening skills, phonemic processing and speech perception in noise are impaired in MS patients which can have significant impacts on their quality of life. Keywords: Auditory processing; multiple sclerosis, central auditory nervous system; adults; speech perception

Is jet fuel exposure associated with central auditory nervous system difficulties: An exploratory study in military personnel.

Central auditory nervous system dysfunction (CANSD) can manifest as hearing difficulty in the absence of audiometric abnormalities. Effects of noise or jet fuel exposure on the CANS are documented in animal models and humans. This study screened military personnel using the modified Amsterdam Inventory for Auditory Disability (mAIAD) to assess whether concurrent jet fuel and noise (JFN) exposures potentiate central auditory difficulties compared to noise only exposures. A total of 48 age- and sex-matched participants were recruited: 24 military bulk fuel specialists (JFN) and 24 military personnel without jet fuel exposure. All participants completed the mAIAD, the Noise Exposure Questionnaire, and basic audiological testing. Results revealed non-significant differences in pure-tone thresholds between groups, but the JFN group had higher noise exposures. Additionally, the JFN group revealed consistently lower mAIAD scores compared to the noise only group. Interestingly, a JFN stratified subgroup reporting more listening difficulty exhibited statistically significant lower mAIAD scores in the speech intelligibility in noise subdomain. These preliminary data suggest that jet fuel exposure may potentiate noise-induced CANSD, such as speech-in-noise difficulties. Such difficulties may be more prominent among specific military personnel with combined exposures. Hearing conservation programs could add CANSD screening by use of the mAIAD.

Evaluation of Medial Olivocochlear Neural Efferent Pathway in Tinnitus Perception in Normal-hearing Individuals.

The objective of this study is to investigate a possible role of the Medial Olivocochlear (MOC) efferent neural pathway and neural connections responsible for tinnitus generation in silence/sensory deprivation. By placing normal hearing participants in a sound booth for 10 minutes, silence/sensory deprivation was created. This offered assessment of MOC neural pathway in normal hearing participants in silence. Hyperactivity of MOC neural pathway was assessed by its more suppressive effect on Transient Otoacoustic Emissions (TEOAEs) in silence. The required auditory measurements were recorded in the sound booth using recommended diagnostic protocols to ensure the effect of 'only silence' on auditory structures. TEOAE were recorded from the right ear and suppression was measured by placing noise in the left ear. Fifty-eight normal hearing male individuals between age 18-35 years were recruited as participants in this study. Approximately, forty-one percent of the participants perceived some type of tinnitus during/after 10 minutes of silence. No statistically significant difference was found in the total TEOAE amplitude and TEOAE suppression amplitude before and after ten minutes of silence. Post silence total TEOAE suppression between tinnitus perceiving and non-perceiving tinnitus participants were not statistically significantly different. These results suggest that the medial olivocochlear efferent pathway or lower brain stem area does not appear to play a role in the emergence of temporary tinnitus in silence however indicate the involvement of higher central auditory nervous system structures in perception of the tinnitus which support the well-accepted notion that tinnitus is the central auditory processing phenomenon.