Distortion Product Otoacoustic Emissions Research Articles

Distortion Product Otoacoustic Emission and Tinnitus: Role of Outer Hair Cells in the Genesis of Tinnitus

Background: This study aims to detect outer hair cell (OHC) function in patients with tinnitus, by comparing the otoacoustic emissions (OAEs) in tinnitus patients with normal hearing and normal-hearing subjects without tinnitus, thereby revealing the role of OHC in the generation of tinnitus. Methods: After approval by the local research and ethics committee, this study was done in the department of otolaryngology and associated hospitals, from April 2022 to January 2023. Consent was obtained from all the participants in the present work after explaining the test procedure. The study group included 60 subjects with bilaterally normal hearing to participate. They were classified into two groups: Group 1, i.e., the control group, comprised 30 subjects who were unaffected by tinnitus, whereas Group 2, i.e., the study group, comprised 30 subjects who were suffering from tinnitus. Basic audiological tests and OAE test were done on the respondents of both the groups followed by a comparison of outcomes. Results: The authors of the present study found a statistically significant difference between the amplitude and signal-to-noise ratio (SNR) of distortion product OAE (DPOAE) in tinnitus patients and the control group without tinnitus, suggesting that OHCs have a role in the generation of tinnitus. Conclusion: It can be concluded that OHC activity was reduced in patients with tinnitus, as detected by reduced DPOAE amplitude and SNR, suggesting that the dysfunction of OHCs can be attributable to the generation of tinnitus.

Splicing mutations of GSDME cause late-onset non-syndromic hearing loss

Objective:To dentify the genetic and audiological characteristics of families affected by late-onset hearing loss due to GSDMEgene mutations, aiming to explore clinical characteristics and pathogenic mechanisms for providing genetic counseling and intervention guidance. Methods:Six families with late-onset hearing loss from the Chinese Deafness Genome Project were included. Audiological tests, including pure-tone audiometry, acoustic immittance, speech recognition scores, auditory brainstem response, and distortion product otoacoustic emission, were applied to evaluate the hearing levels of patients. Combining with medical history and physical examination to analyze the phenotypic differences between the probands and their family members. Next-generation sequencing was used to identify pathogenic genes in probands, and validations were performed on their relatives by Sanger sequencing. Pathogenicity analysis was performed according to the American College of Medical Genetics and Genomics Guidelines. Meanwhile, the pathogenic mechanisms of GSDME-related hearing loss were explored combining with domestic and international research progress. Results:Among the six families with late-onset hearing loss, a total of 30 individuals performed hearing loss. The onset of hearing loss in these families ranged from 10 to 50 years（mean age: 27.88±9.74 years）. In the study, four splicing mutations of the GSDME were identified, including two novel variants: c. 991－7C>G and c. 1183+1G>T. Significantly, the c. 991－7C>G was a de novo variant. The others were previously reported variants: c. 991-1G>C and c. 991-15_991-13del, the latter was identified in three families. Genotype-phenotype correlation analysis revealed that probands with the c. 991－7C>G and c. 1183+1G>T performed a predominantly high-frequency hearing loss. The three families carrying the same mutation exhibited varying degrees of hearing loss, with an annual rate of hearing deterioration exceeding 0.94 dB HL/year. Furthermore, follow-up of interventions showed that four of six probands received intervention（66.67%）, but the results of intervention varied. Conclusion:The study analyzed six families with late-onset non-syndromic hearing loss linked to GSDME mutations, identifying four splicing variants. Notably, c. 991－7C>G is the first reported de novo variant of GSDME globally. Audiological analysis revealed that the age of onset generally exceeded 10 years,with variable effectiveness of interventions.

ДИНАМИКА ПОКАЗАТЕЛЕЙ ФУНКЦИОНАЛЬНОГО СОСТОЯНИЯ ОРГАНА СЛУХА И СОСТАВА МИКРОФЛОРЫ ЛОР-ОРГАНОВ ЧЕЛОВЕКА В УСЛОВИЯХ НАЗЕМНОГО МОДЕЛИРОВАНИЯ ЭФФЕКТОВ МИКРОГРАВИТАЦИИ

Functioning of hearing organs and ENT microflora composition were investigated in 10 healthy male subjects (25–36 y.o.) who volunteered for a 7-day dry immersion as a model of the physiological effects of microgravity. The functional state of the hearing organs was assessed with the registration of distortion product oto-acoustic emission (DPOAE), and tympanometry. Specifically, assessed were the signal-to-noise ratio (SNR) of the oto-acoustic response (dB), middle ear pressure (daPa) and tympanogram maximal compliance (ml). To identify and count ENT microbial cultures, samples were gathered from the nasal and pharyngeal membranes and external skin of the auditory meatus. The eubiotic index was used to detect changes in the microflora composition. Changes in the hearing organ functioning included a SNR decrease in DPOAE of the low-frequency band (p ≤ 0.05), increase of the middle ear pressure (p ≤ 0.05) and an obvious downward trend of the maximal compliance. Dynamic microbiocenosis assessment discovered several negative changes such as a reduction in the number of protective microorganisms and growth of the number of opportunistic groups. The eubiotic index value was below one. These changes demonstrate a potential negative effect of modeled microgravity on the ENT microflora functioning and composition. Methods of dynamic assessment and control of the hearing organ and ENT microbiocenosis would be appropriate for use in monitoring of cosmonauts' health.

Management of pediatric sensory neural hearing loss: a case report

Abstract Early childhood is the age of learning and experiencing various things through hearing or seeing. Any abnormality in hearing in this age group makes the child dull and self-isolating, affecting his morale. This is a case of an 8-year-old boy with deficient hearing from both ears, which was left unnoticed until the age of 5 years. There is no similar family history. The antenatal and neonatal history was found to be normal, but the child used to get fever and upper respiratory tract infection very frequently. The patient was taken for an otorhinology consultation after being noticed nonresponsive to moderately loud sounds and calls from behind. Otologic investigations—brain-evoked response audiometry and distortion product otoacoustic emissions—revealed bilateral mild-to-moderate hearing loss. Ayurveda treatment was given with 8 months of follow-up, and investigations were recorded. The aim of this report was to analyze a case of sensorineural hearing loss (SNHL) in a pediatric age group and its management through Ayurveda. The site of this study was the National Institute of Ayurveda Hospital, Jaipur, and this is a single-case report. All the relevant history was taken, followed by the investigations required for the case. Since the patient was a minor, consent was obtained from his father for the publication of this case report. For the conceptual part, various textbooks and research papers on Ayurveda and allopathy available online and offline were referred to. The patient was advised to go for speech therapy along with the Ayurvedic treatment Karnapoorana and other oral formulations. After 8 months of follow-up, this patient was found to be more responsive with improved hearing and general immunity.

Role of Otoacoustic Emissions in Hearing Assessment of Children with Autism

Evaluation of hearing is essential in the diagnostic process of children suspected having autism spectrum disorder (ASD). The aim of this study was to examine the efficiency and feasibility of utilizing otoacoustic emissions as an objective test to assess hearing in children diagnosed with ASD. A pilot study was conducted over a period of 3 years (from September 2019 to November 2022) in the Audiology Department at the Center for Specialty Surgeries, Benghazi, Libya. A total of 61 children with autism aged between 2-15 years referred for hearing evaluation were enrolled in the study. The clinical procedure consisted of otoscopic ear examination, and Otoacoustic Emission (OAE) recording. OAE testing was attempted on the study sample (n 51) who met the inclusion criteria. And successfully completed for 44 participants (86%): 40 cases (91%) from the first attempt while 4 cases (9%) needed a second or more visit. Four autistic children (9%) had absent otoacoustic emissions in one ear. Testing couldn't be completed for 7 children (14%) due to behavioral difficulties. Results of this study showed the feasibility of using Distortion Product Otoacoustic Emissions (DPOAEs) in assessment of hearing for children with autism for whom obtaining reliable behavioral responses can be challenging.

Prevalence and risk factors of hearing loss in high-risk neonates at a tertiary care hospital in Mumbai

Background: The present study was conducted to assess the prevalence of hearing loss using measurements of otoacoustic emission (OAE) in newborns admitted to NICU and to determine the risk factors predictive of hearing impairment in these newborns. Methods: This was a Prospective observational study conducted among 220 newborns admitted to the NICU over 18 months. Ethical clearance was obtained from the IEC. The sample size was obtained by the universal sampling technique. All candidates underwent hearing assessment in a sound-treated room in the department using a distortion product OAEs (DPOAE) test at the time of discharge. Babies who did not pass the initial screening underwent another OAE test within one month after being discharged. If they failed the test again, they were referred to an otologist for BERA. Results: Of the 226 neonates included in the study, 40 cases (17.7%) failed the initial screening. 29 cases (12.8%) failed the second OAE screening and were subjected to BERA. Risk factors included asphyxia (p≤0.001), mechanical ventilation (p<0.0004), history of ototoxic medication (p=0.004), neonates with hyperbilirubinemia requiring exchange transfusion (p=0.005), low Apgar scores (p≤0.001). Conclusions: A two-stage OAE hearing screening can be a suitable method for early detection of hearing impairment in newborns. This method has shown high prevalence of hearing loss among high-risk neonates but needs to be confirmed with diagnostic BERA. It is crucial to have universal hearing screening to detect the large number of hearing-impaired neonates in the newborn population of our country, including those who are not considered at risk.

KMT2D Deficiency Causes Sensorineural Hearing Loss in Mice and Humans.

Individuals with Kabuki syndrome type 1 (KS1) often have hearing loss recognized in middle childhood. Current clinical dogma suggests that this phenotype is caused by frequent infections due to the immune deficiency in KS1 and/or secondary to structural abnormalities of the ear. To clarify some aspects of hearing loss, we collected information on hearing status from 21 individuals with KS1 and found that individuals have both sensorineural and conductive hearing loss, with the average age of presentation being 7 years. Our data suggest that while ear infections and structural abnormalities contribute to the observed hearing loss, these factors do not explain all loss. Using a KS1 mouse model, we found hearing abnormalities from hearing onset, as indicated by auditory brainstem response measurements. In contrast to mouse and human data for CHARGE syndrome, a disorder possessing overlapping clinical features with KS and a well-known cause of hearing loss and structural inner ear abnormalities, there are no apparent structural abnormalities of the cochlea in KS1 mice. The KS1 mice also display diminished distortion product otoacoustic emission levels, which suggests outer hair cell dysfunction. Combining these findings, our data suggests that KMT2D dysfunction causes sensorineural hearing loss compounded with external factors, such as infection.

Zinc deficiency triggers hearing loss by reducing ribbon synapses of inner hair cells in CBA/N mice

Zinc plays a vital role in our metabolism, encompassing antioxidant regulation, immune response, and auditory function. Several studies have reported that zinc levels correlate with hearing loss. We have previously demonstrated that the auditory brainstem response (ABR) threshold increased in mice fed a zinc-deficient diet. However, the effects of zinc deficiency on hearing were not fully elucidated. The present study investigated whether zinc deficiency affects hearing in association with neuronal components or cochlear structures. CBA/N mice were fed a normal or zinc-deficient diet for 8 weeks and assessed for ABR and distortion product otoacoustic emissions (DPOAE). The cochlear sections were stained with hematoxylin and eosin solution. Also, we observed the expression of synaptic ribbons, neurofilaments, and alpha-synuclein (α-Syn). The 8-week zinc-deficient diet mice had an elevated ABR threshold but no changed DPOAE threshold or cochlear structures. A reduced number of synaptic ribbons of inner hair cells (IHCs) and impaired efferent nerve fibers were observed in the zinc-deficient diet mice. The number of outer hair cells (OHCs) and expression of α-Syn remained unchanged. Our results suggest that zinc-mediated hearing loss is associated with the loss of neuronal components of IHCs.

Assessing the auditory effects of oral chelation therapy drug Deferasirox in individuals with β‐thalassemia major

AbstractObjectiveOur study aimed to investigate the ototoxicity associated with the iron chelator deferasirox in patients with β‐thalassemia major, who were receiving regular transfusion therapy, along with evaluating the data on audiological tests using appropriate statistical tests.MethodsA cross‐sectional observational study was conducted on 100 transfusion‐dependent β‐thalassemia major patients on oral iron chelating agent‐deferasirox. Pure tone audiometry (PTA) and distortion product otoacoustic emissions (DPOAE) was carried out in all patients to assess the auditory side effects of the drug. Data was collected, compiled, and analyzed statistically using appropriate statistical tests. The relationship between ototoxicity and various demographic parameters such as age, sex, hemoglobin (Hb) level, S. ferritin, duration, and dose of chelation therapy was also assessed.ResultsSixteen patients had abnormal DPOAE and the number of patients with pure tone average above 25 dB HL which was taken as hearing deficit on PTA was 13. No statistically significant relationship between hearing loss and age, gender, S. ferritin, duration of therapy, cumulative dose, Hb levels were found.ConclusionDespite being a lifesaving drug, the advantages of chelating agent‐Deferasirox must be weighed against its probable ototoxic effects. We could not find a relationship of ototoxicity with variable parameters (age, gender, Hb level, Ferritin level, duration, and cumulative dose of drug), thus future research is encouraged to form a definitive basis.

Heightened OAEs in young adult musicians: Influence of current noise exposure and training recency

Otoacoustic emissions (OAEs) are a non-invasive metric of cochlear function. Studies of OAEs in musicians have yielded mixed results, ranging from evidence of diminished OAEs in musicians—suggesting noise-induced hearing loss—to no difference when compared to non-musicians, or even a trend for stronger OAEs in musicians. The goal of this study was to use a large sample of college students with normal hearing (n = 160) to compare OAE SNRs in musicians and non-musicians and to explore potential effects of training recency and noise exposure on OAEs in these cohorts. The musician cohort included both active musicians (who at the time of enrollment practiced at least weekly) and past musicians (who had at least 6 years of training). All participants completed a questionnaire about recent noise exposure (previous 12 months), and a subset of participants (71 musicians and 15 non-musicians) wore a personal noise dosimeter for one week to obtain a more nuanced and objective measure of exposure to assess how different exposure levels may affect OAEs before the emergence of a clinically significant hearing loss. OAEs were tested using both transient-evoked OAEs (TEOAEs) and distortion-product OAEs (DPOAEs). As predicted from the literature, musicians experienced significantly higher noise levels than non-musicians based on both subjective (self-reported) and objective measures. Yet we found stronger TEOAEs and DPOAEs in musicians compared to non-musicians in the ∼1–5 kHz range. Comparisons between past and active musicians suggest that enhanced cochlear function in young adult musicians does not require active, ongoing musical practice. Although there were no significant relations between OAEs and noise exposure as measured by dosimetry or questionnaire, active musicians had weaker DPOAEs than past musicians when the entire DPOAE frequency range was considered (up to ∼16 kHz), consistent with a subclinical noise-induced hearing loss that only becomes apparent when active musicians are contrasted with a cohort of individuals with comparable training but without the ongoing risks of noise exposure. Our findings suggest, therefore, that separate norms should be developed for musicians for earlier detection of incipient hearing loss. Potential explanations for enhanced cochlear function in musicians include pre-existing (inborn or demographic) differences, training-related enhancements of cochlear function (e.g., upregulation of prestin, stronger efferent feedback mechanisms), or a combination thereof. Further studies are needed to determine if OAE enhancements offer musicians protection against damage caused by noise exposure.

Comprehensive behavioral and physiologic assessment of peripheral and central auditory function in individuals with mild traumatic brain injury

Auditory complaints are frequently reported by individuals with mild traumatic brain injury (mTBI) yet remain difficult to detect in the absence of clinically significant hearing loss. This highlights a growing need to identify sensitive indices of auditory-related mTBI pathophysiology beyond pure-tone thresholds for improved hearing healthcare diagnosis and treatment. Given the heterogeneity of mTBI etiology and the diverse peripheral and central processes required for normal auditory function, the present study sought to determine the audiologic assessments sensitive to mTBI pathophysiology at the group level using a well-rounded test battery of both peripheral and central auditory system function. This test battery included pure-tone detection thresholds, word understanding in quiet, sentence understanding in noise, distortion product otoacoustic emissions (DPOAEs), middle-ear muscle reflexes (MEMRs), and auditory evoked potentials (AEPs), including auditory brainstem responses (ABRs), middle latency responses (MLRs), and late latency responses (LLRs). Each participant also received magnetic resonance imaging (MRI). Compared to the control group, we found that individuals with mTBI had reduced DPOAE amplitudes that revealed a compound effect of age, elevated MEMR thresholds for an ipsilateral broadband noise elicitor, longer ABR Wave I latencies for click and 4 kHz tone burst elicitors, longer ABR Wave III latencies for 4 kHz tone bursts, larger MLR Na and Nb amplitudes, smaller MLR Pb amplitudes, longer MLR Pa latencies, and smaller LLR N1 amplitudes for older individuals with mTBI. Further, mTBI individuals with combined hearing difficulty and noise sensitivity had a greater number of deficits on thalamic and cortical AEP measures compared to those with only one/no self-reported auditory symptoms. This finding was corroborated with MRI, which revealed significant structural differences in the auditory cortical areas of mTBI participants who reported combined hearing difficulty and noise sensitivity, including an enlargement of left transverse temporal gyrus (TTG) and bilateral planum polare (PP). These findings highlight the need for continued investigations toward identifying individualized audiologic assessments and treatments that are sensitive to mTBI pathophysiology.

Evaluation of Lifetime Noise Exposure History Reporting.

The purpose of this study is to critically evaluate lifetime noise exposure history (LNEH) reporting. First, two different approaches to evaluate the cumulative LNEH were compared. Second, individual LNEH was associated with the subjects' hearing status. Third, loudness estimates of exposure activities, by means of Jokitulppo- and Ferguson-based exposure levels, were compared with dosimeter sound-level measurements. One hundred one young adults completed the questionnaires, and a subgroup of 30 subjects underwent audiological assessment. Pure-tone audiometry, speech-in-noise intelligibility, distortion product otoacoustic emissions, auditory brainstem responses, and envelope following responses were included. Fifteen out of the 30 subjects took part in a noisy activity while wearing a dosimeter. First, results demonstrate that the structured questionnaire yielded a greater amount of information pertaining to the diverse activities, surpassing the insights obtained from an open-ended questionnaire. Second, no significant correlations between audiological assessment and LNEH were found. Lastly, the results indicate that Ferguson-based exposure levels offer a more precise estimation of the actual exposure levels, in contrast to Jokitulppo-based estimates. We propose several recommendations for determining the LNEH. First, it is vital to define accurate loudness categories and corresponding allocated levels, with a preference for the loudness levels proposed by Ferguson et al. (2019), as identified in this study. Second, a structured questionnaire regarding LNEH is recommended, discouraging open-ended questioning. Third, it is essential to include a separate category exclusively addressing work-related activities, encompassing various activities for more accurate surveying.

Effects of Body Position on Cochlear Function in Infants: An Otoacoustic Emission Study.

Otoacoustic Emission (OAE) is frequently recorded in various body positions for infants. However, little is available about whether these deviations will produce non-pathological effects on the clinical results. The current study assessed body position's effect on infants' inner ear function. Sixty normally hearing infants participated in an analytical cross-sectional study. Distortion-product OAEs (DPOAEs) were measured in the supine, side-lying, and upright positions. The DPOAE amplitude and signal-to-noise ratio (SNR) were recorded across the 1500 to 6000Hz range. The mean DPOAE amplitude and SNR values were significantly greater in the upright position than supine and side-lying positions (p < 0.05). These differences were more pronounced in the 3000 to 6000Hz range. The effects of gender and ear asymmetry on DPOAEs were not statistically significant. Our findings suggested that the upright position could be regarded as the best position for assessing DPOAEs in infants.

Mitigation ofHearing Damage With Liraglutide Treatment inChinchillas After Repeated Blast Exposures at Mild-TBI.

Although hearing protection devices (HPDs) have been widely used during training and combat, over one million veterans experience service-connected hearing loss. Hearing damage has been reported to be associated with blast-induced mild traumatic brain injury (mTBI) and there is a lack of understanding and treatment. Liraglutide is a glucagon-like peptide-1 receptor agonist and a potential treatment for TBI-induced memory deficits. This study aims to investigate the function of the liraglutide to prevent damage and facilitate hearing restoration in chinchillas exposed to multiple high-intensity, mTBI-level blasts. Chinchillas were divided into three treatment groups: blast control, pre-blast drug treatment, and post-blast drug treatment. On day 1, the chinchilla ears were protected by HPDs and exposed to three blasts with peak pressure levels of 15-25 psi. The auditory brainstem response (ABR), distortion product otoacoustic emission (DPOAE), and middle latency response (MLR) were recorded pre- and post-blast on day 1 and on days 4, 7, 14, and 28. Substantial acute damage was observed and progressively recovered in chinchillas after the blast exposures. The pre-blast treatment group exhibited the lowest elevation of the ABR threshold and reduction of the wave I amplitude on day 1 after blasts. The liraglutide treatment insignificantly facilitated the recovery of the DPOAE levels and ABR thresholds on days 14 and 28. The pre-blast treatment chinchillas showed reduced MLR amplitudes on days 4 and 7. This study indicated that the pre-blast liraglutide administration provided damage protection against blasts in addition to the HPDs. Current evidence suggests that the effect of liraglutide is more prominent in the early phase of the experiment.

Cochlear metabolomics, highlighting novel insights of purine metabolic alterations in age-related hearing loss

Aging is an inevitable phase in mammals that leads to health impairments, including hearing loss. Age-related hearing loss (AHL) leads to psychosocial problems and cognitive decline in the elderly. In this study, mean thresholds of auditory brainstem responses (ABR) and distortion-product otoacoustic emissions (DPOAE) increased at multiple frequencies in aged rats (14 months old) compared to young rats (2 months old). Using untargeted ultra-high performance liquid chromatography-mass spectroscopy (LC-MS), we quantified molecular metabolic markers in the cochlea of aged rats with hearing loss. A total of 137 different metabolites were identified in two groups, highlighting several prominent metabolic pathways related to purine metabolism; glycine, serine, and threonine metabolism; arginine and proline metabolism; and pyrimidine metabolism. In addition, the beneficial effects of purine supplementation were demonstrated in a mimetic model of senescent marginal cells (MCs). Overall, altered metabolic profiling is both the cause and manifestation of pathology, and our results suggest that cellular senescence and dysfunctional cochlear metabolism may contribute to the progression of AHL. These findings are seminal in elucidating the pathophysiological mechanisms underlying AHL and serve as a basis for future clinical predictions and interventions in AHL.

Hearing characteristics and otoradiological abnormalities in three patients with novel pathogenic variants of KMT2D-related Kabuki syndrome.

Kabuki syndrome 1 (KS1; OMIM:147920), which is characterized by distinctive dysmorphic facial features (such as arched eyebrows, long palpebral fissures with eversion of the lower lid, and large protuberant ears), intellectual disability, short stature, and dermatoglyphic and skeletal abnormalities, is brought on by pathogenic variants in KMT2D (OMIM:602113). In this work, three individuals with novel pathogenic KMT2D gene variants had their longitudinal audiological manifestations and ear structural characteristics outlined. The longitudinal audiological data from neonatal hearing screening and a battery of several hearing tests were evaluated. The battery of hearing tests included tympanometry, distortion product otoacoustic emission (DPOAE), click-evoked air-conduction auditory brain-stem response (AC-ABR), click-evoked bone-conduction auditory brain-stem response (BC-ABR), narrow band CE-chirp auditory steady-state response (NB CE-chirp ASSR), and pure-tone audiometry (PTA). Phenotype identification and whole exome sequencing (WES) were performed on recruited individuals. All three patients (two females and on male; last evaluations at 14 months, 11 months, and 5.7 years, respectively) failed the newborn hearing screening, and the audiological follow-up data revealed mild to profound fluctuating hearing loss, which was directly influenced by the incidence and severity of otitis media with effusion (OME). When OME occurred, the AC-ABR thresholds increased from 30-75 dBnHL to 45-90 dBnHL. The threshold for the BC-ABR and BC-PTA was between 25 and 50 dBnHL, indicating mild to moderate sensorineural hearing loss (SNHL). The high-resolution computed tomography (HRCT) pictures indicated that all three patients had middle and inner ear abnormalities. Middle ear anomalies showed as diminished mastoid gasification and ossicle dysplasia. Cochlear dysplasia, a dilated vestibule, fusion of the vestibule with the horizontal semicircular canals, and a short and thick horizontal semicircular canal were visible on images of the inner ear. This study recruited three individuals with three novel pathogenic variants (c.5104C>T, c.10205delA, and c.12840delC) of KMT2D who were identified at ages 27 days, 2 months, and 5.5 years. Hearing characteristics of three individuals with three novel pathogenic variants of KMT2D range from mild to profound fluctuating hearing loss with mild to moderate SNHL. HRCT scans showed that all three individuals had anatomical middle and inner ear abnormalities. KS 1 patients must get clinical therapy for OME, frequent auditory monitoring, and prompt intervention.

Relationship between hypertension/blood pressure and hearing sensitivity among drivers: A correlation analysis.

One of the most common chronic diseases is hypertension. The majority of research has linked hearing loss to hypertension. However, the relationship between hypertension and hearing is still unknown. The primary goal of the study is to investigate the effect of hypertension on hearing and to find out the association between blood pressure levels and auditory health in auto-rickshaw drivers. The study utilized 121 healthy professional auto-drivers between the age range of 25 and 55 years. Pure-tone audiometry (PTA) and extended high-frequency audiometry (EHFA) were used to determine the participants' hearing thresholds from 0.25 to 16 kHz. The cochlear hair cell functioning was evaluated using distortion-product otoacoustic emission (DPOAE) testing. Blood pressure (mmHg) measurements were categorized under hypertension stage (normal (120; <80); elevated (120-129; <80); hypertension - stage 1 (130-139; 80-89); hypertension - stage 2 (≥140; ≥90)). The mean age of the study participants was 42.17 ± 9.03 years. The mean systolic and diastolic BP of all the study participants were 138.24 ± 19.73 (105-216) mmHg and 87.69 ± 12.14 (60-134) mmHg, respectively. BP levels were normal for 17.4% (N = 21) of the study participants, 21.5% (N = 26) had elevated blood pressure, 21.5% (N = 26) of the population falls under stage 1 hypertension, and 39.7% (N = 48) had stage 2 hypertension. Our study discovered a significant difference between main group effects and no significant difference between group interaction effects. Hearing thresholds were significantly higher in hypertensive participants compared to non-hypertensive participants. However, there was no statistically significant relationship between the two variables hypertension and hearing loss. Implementing health promotion initiatives and raising awareness about hearing health could improve the quality of life for a high-risk occupational group of drivers.

Acoustic differences in tinnitus between noise-induced and non-noise-induced hearing loss

Background Tinnitus, the perception of sound without external stimuli, varies across hearing loss types. The present study compared the acoustic characteristics of tinnitus in patients with noise-induced hearing loss (NIHL) and in those with hearing loss unrelated to noise exposure. Objective This study compared the acoustic characteristics of tinnitus in patients with noise-induced and non-noise-induced hearing loss. Methods A total of 403 patients with tinnitus were divided into those with noise-induced and non-noise-induced hearing loss. Patients were evaluated by pure tone audiometry (PTA), tinnitogram, transient evoked otoacoustic emission (TEOAE), distortion product otoacoustic emission (DPOAE), and auditory brainstem evoked response (ABR) tests. Results Patients with NIHL exhibited significantly higher hearing thresholds across all frequencies (125–8000 Hz) (p < .05) and reported significantly higher tinnitus intensity (p < .05). Otoacoustic emission tests showed that response rates were significantly lower (p < .05), and ABR tests found that latency periods were significantly more prolonged (p < .05), in patients with NIHL. Conclusions Tinnitus differs acoustically between patients with NIHL and those with non-noise-induced hearing loss, with specific patterns of intensity and auditory responses. These findings emphasize the need for tailoring the management of tinnitus according to the underlying type of hearing loss.

Normal linear and non-linear cochlear mechanisms and efferent system functioning in individuals with misophonia.

Misophonia, a condition characterized by heightened sensitivity and strong emotional reactions to specific sounds, has sparked considerable interest and debate regarding its underlying auditory mechanisms. The study aimed to understand the auditory underpinnings of two such potential inner ear systems, non-linear and linear outer hair cell functioning along with auditory efferent functioning in individuals with misophonia. 40 ears with misophonia (20 participants) and 37 ears without misophonia (20 participants), both having normal hearing sensitivity were included in this study. Transient evoked otoacoustic emissions (TEOAEs) and distortion product otoacoustic emissions (DPOAEs) were obtained in two conditions (with and without contralateral noise). Results of independent-samples t-test showed no statistically significant difference (p > 0.05) in the absolute amplitudes of both TEOAEs and DPOAEs between the individuals with and without misophonia. There was no statistically significant difference (p > 0.05) observed in the magnitude of suppression amplitude between the two groups for in both TEOAEs and DPOAEs between individuals with and without misophonia. These results suggest that the cochlear and efferent auditory underpinnings examined in this study may not be major contributors to the development or manifestation of misophonia.

Preserved Auditory Steady State Response and Envelope-Following Response in Severe Brainstem Dysfunction Highlight the Need for Cross-Checking.

Commercially available auditory steady state response (ASSR) systems are widely used to obtain hearing thresholds in the pediatric population objectively. Children are often examined during natural or induced sleep so that the recorded ASSRs are of subcortical origin, the inferior colliculus being often designated as the main ASSR contributor in these conditions. This report presents data from a battery of auditory neurophysiological objective tests obtained in 3 cases of severe brainstem dysfunction in sleeping children. In addition to ASSRs, envelope-following response (EFR) recordings designed to distinguish peripheral (cochlear nerve) from central (brainstem) were recorded to document the effect of brainstem dysfunction on the two types of phase-locked responses. Results obtained in the 3 children with severe brainstem dysfunctions were compared with those of age-matched controls. The cases were identified as posterior fossa tumor, undiagnosed (UD), and Pelizaeus-Merzbacher-Like Disease. The standard audiological objective tests comprised tympanograms, distortion product otoacoustic emissions, click-evoked auditory brainstem responses (ABRs), and ASSRs. EFRs were recorded using horizontal (EFR-H) and vertical (EFR-V) channels and a stimulus phase rotation technique allowing isolation of the EFR waveforms in the time domain to obtain direct latency measurements. The brainstem dysfunctions of the 3 children were revealed as abnormal (weak, absent, or delayed) ABRs central waves with a normal wave I. In addition, they all presented a summating and cochlear microphonic potential in their ABRs, coupled with a normal wave I, which implies normal cochlear and cochlear nerve function. EFR-H and EFR-V waveforms were identified in the two cases in whom they were recorded. The EFR-Hs onset latencies, response durations, and phase-locking values did not differ from their respective age-matched control values, indicating normal cochlear nerve EFRs. In contrast, the EFR-V phase-locking value and onset latency varied from their control values. Both patients had abnormal but identifiable and significantly phase-locked brainstem EFRs, even in a case with severely distorted ABR central waves. ASSR objective audiograms were recorded in two cases. They showed normal or slightly elevated (explained by a slight transmission loss) thresholds that do not yield any clue about their brainstem dysfunction, revealing the method's lack of sensitivity to severe brainstem dysfunction. The present study, performed on 3 sleeping children with severe brainstem dysfunction but normal cochlear responses (cochlear microphonic potential, summating potential, and ABR wave I), revealed the differential sensitivity of three auditory electrophysiological techniques. Estimated thresholds obtained by standard ASSR recordings (cases UD and Pelizaeus-Merzbacher-Like Disease) provided no clue to the brainstem dysfunction clearly revealed by the click-evoked ABR. EFR recordings (cases posterior fossa tumor and UD) showed preserved central responses with abnormal latencies and low phase-locking values, whereas the peripheral EFR attributed to the cochlear nerve was normal. The one case (UD) for which the three techniques could be performed confirms this sensitivity gradient, emphasizing the need for applying the Cross-Check Principle by avoiding resorting to ASSR recording alone. The entirely normal EFR-H recordings observed in two cases further strengthen the hypothesis of its cochlear nerve origin in sleeping children.