Amplitude Of Otoacoustic Emissions Research Articles

Influence of Different Types of Contralateral Suppression Tones on Otoacoustic Emission in Children With Autism Spectrum Disorder

Background and Objectives: Auditory sensory gating deficits are abnormalities in patients with autism spectrum disorder (ASD) that may lead to sensory processing difficulties. It is particularly difficult for children with ASD to distinguish multiple auditory stimuli, which hinders them from focusing on a single auditory stimulus and separating unnecessary sounds. Suppression of otoacoustic emission (OAE) is an approach used to identify sensory gating deficits in the general population, specifically for children with ASD. This study aimed to investigate the suppression effect of various types of sound suppressors to measure their sensory gating capacity in children with ASD.Subjects and Methods: Twenty children including 10 with ASD and 10 normally developing children aged 6-12 years were recruited for this study. One accessible ear was exposed to transient-evoked OAE, whereas the other was exposed to suppressor tones. Contralateral suppressors included white noise, Quranic recitations, environmental noise, and natural sound. The magnitude of OAE suppression was determined from the difference between the OAE amplitude with and without the masker (in dB sound pressure levels) for all sound types. The sound with the highest suppression effect was determined using effect size calculation and repeated-measures analysis of variance at a 95% confidence level. A high suppression effect may suggest a high sensory gating performance, whereas low suppression may indicate low sensory gating performance.Results: Based on the analysis, the sound with the highest suppression effect was that of the waterfall. The suppression results were supported by descriptive analysis findings and effect-size calculations.Conclusions: This study provides a better understanding of the alternative sound stimuli, besides the standard white noise tone, for the assessment of sensory gating deficits among children with ASD. Sounds with a high suppression effect have the potential to be used as sound therapy interventions for children with ASD as part of rehabilitation and therapy.

MRI noise and auditory health: Can one hundred scans be linked to hearing loss? The case of the Courtois NeuroMod project.

Magnetic resonance imaging (MRI) is one of the most commonly used tools in neuroscience. However, it implies exposure to high noise levels. Exposure to noise can lead to temporary or permanent hearing loss, especially when the exposure is long and/or repeated. Little is known about the hearing risks for people undergoing several MRI examinations, especially in the context of longitudinal studies. The goal of this study was to assess the potential impact of repeated exposure to MRI noise on hearing in research participants undergoing dozens of MRI scans. This investigation was made possible thanks to an unprecedented intensive MRI research data collection effort (the Courtois NeuroMod project) where participants have been scanned weekly (up to twice a week), with the use of hearing protection, since 2018. Their hearing was tested periodically, over a period of 1.5 years. First, baseline pure-tone thresholds and distortion product otoacoustic emission (DPOAE) amplitudes were acquired before the beginning of this study. Hearing tests were then scheduled immediately before/immediately after a scan and with a delay of two to seven days after a scan. Pure-tone thresholds and DPOAE amplitudes showed no scanner noise impact right after the scan session when compared to the values acquired right before the scan session. Pure-tone thresholds and DPOAE amplitudes acquired in the delayed condition and compared to the baseline showed similar results. These results suggest an absence of impact from MRI noise exposure. Overall, our results show that an intensive longitudinal MRI study like the Courtois NeuroMod project likely does not cause hearing damage to participants when they properly utilize adequate hearing protection.

Detection of mild sensory hearing loss using a joint reflection-distortion otoacoustic emission profile.

Measuring and analyzing both nonlinear-distortion and linear-reflection otoacoustic emissions (OAEs) combined creates what we have termed a "joint-OAE profile." Here, we test whether these two classes of emissions have different sensitivities to hearing loss and whether our joint-OAE profile can detect mild-moderate hearing loss better than conventional OAE protocols have. 2f1-f2 distortion-product OAEs and stimulus-frequency OAEs were evoked with rapidly sweeping tones in 300 normal and impaired ears. Metrics included OAE amplitude for fixed-level stimuli as well as slope and compression features derived from OAE input/output functions. Results show that mild-moderate hearing loss impacts distortion and reflection emissions differently. Clinical decision theory was applied using OAE metrics to classify all ears as either normal-hearing or hearing-impaired. Our best OAE classifiers achieved 90% or better hit rates (with false positive rates of 5%-10%) for mild hearing loss, across a nearly five-octave range. In summary, results suggest that distortion and reflection emissions have distinct sensitivities to hearing loss, which supports the use of a joint-OAE approach for diagnosis. Results also indicate that analyzing both reflection and distortion OAEs together to detect mild hearing loss produces outstanding accuracy across the frequency range, exceeding that achieved by conventional OAE protocols.

ABO Blood Group and Auditory Function in Young Adults.

In recent years, research on the effect of blood group on hearing function has gained more attention. Some blood groups show susceptibility to certain general health and auditory disorders like noise induced hearing loss, infections, coronary artery disease, gastric carcinoma and duodenal ulcer. The present study aimed to determine the differences in middle ear and cochlear function among persons with different blood groups (AB, A, B, O). Sixty adults (18-24 years) with normal hearing sensitivity were included in the study. They were divided into four groups based on blood groups (A, B, AB, O) with 15 participants each. High-frequency thresholds, distortion product otoacoustic emissions (DPOAE) and resonance frequency were measured. High-frequency thresholds for both ears were measured at octave frequencies from 9kHz to 16kHz. Resonant frequency was determined using sweep frequency method. The findings demonstrated that individuals with blood group AB and O had considerably lower DPOAE amplitudes. Resonance frequency and extended high frequency thresholds did not, however, differ significantly between the blood groups. The decrease in the amplitude of otoacoustic emissions (OAE) can be explained by a reduction in the quantity of robust outer hair cells and elevated protein levels, which in turn lead to a reduction in the cochlear blood flow in persons with blood type O and AB, respectively. More research with greater numbers of participants is necessary to improve the generalization of the findings.

Effect of Rh- Positive Blood Group on Distortion Product Otoacoustic Emission Input-Output Function.

The blood group system of human beings can impact the health and auditory system. There are correlations between various audiological test findings and blood groups. Studies have shown that persons with the O blood group have reduced resonance frequency of the middle ear and amplitude of otoacoustic emissions. Therefore, Otoacoustic emissions (OAE) results could be different across blood groups. The current study aimed to determine the difference in Distortion product otoacoustic emission input-output function in persons with varying groups of blood. A total of sixty college-going young female adults, aged between 18 and 25years, participated in the current study. They were divided into four groups, each with 15 participants based on the blood group type (A, B. AB. O). The subjects underwent Distortion product otoacoustic emission (DPOAE) input-output function on the following frequencies: 703Hz,1060Hz,1416Hz,2114Hz,2827Hz,4243Hz, and 5645Hz. The analysis showed no significant difference in the area and slope of the Distortion product otoacoustic emission input-output function at all frequencies. Thus, the study's result shows no effect of the blood group on Distortion product otoacoustic emission input- output function.

Auditory Effects of Acoustic Noise From 3-T Brain MRI in Neonates With Hearing Protection.

Neonates with immature auditory function (eg, weak/absent middle ear muscle reflex) could conceivably be vulnerable to noise-induced hearing loss; however, it is unclear if neonates show evidence of hearing loss following MRI acoustic noise exposure. To explore the auditory effects of MRI acoustic noise in neonates. Prospective. Two independent cohorts of neonates (N = 19 and N = 18; mean gestational-age, 38.75 ± 2.18 and 39.01 ± 1.83 weeks). T1-weighted three-dimensional gradient-echo sequence, T2-weighted fast spin-echo sequence, single-shot echo-planar imaging-based diffusion-tensor imaging, single-shot echo-planar imaging-based diffusion-kurtosis imaging and T2-weighted fluid-attenuated inversion recovery sequence at 3.0 T. All neonates wore ear protection during scan protocols lasted ~40 minutes. Equivalent sound pressure levels (SPLs) were measured for both cohorts. In cohort1, left- and right-ear auditory brainstem response (ABR) was measured before (baseline) and after (follow-up) MRI, included assessment of ABR threshold, wave I, III and V latencies and interpeak interval to determine the functional status of auditory nerve and brainstem. In cohort2, baseline and follow-up left- and right-ear distortion product otoacoustic emission (DPOAE) amplitudes were assessed at 1.2 to 7.0 kHz to determine cochlear function. Wilcoxon signed-rank or paired t-tests with Bonferroni's correction were used to compare the differences between baseline and follow-up ABR and DPOAE measures. Equivalent SPLs ranged from 103.5 to 113.6 dBA. No significant differences between baseline and follow-up were detected in left- or right-ear ABR measures (P > 0.999, Bonferroni corrected) in cohort1, or in DPOAE levels at 1.2 to 7.0 kHz in cohort2 (all P > 0.999 Bonferroni corrected except for left-ear levels at 3.5 and 7.0 kHz with corrected P = 0.138 and P = 0.533). A single 40-minute 3-T MRI with equivalent SPLs of 103.5-113.6 dBA did not result in significant transient disruption of auditory function, as measured by ABR and DPOAE, in neonates with adequate hearing protection. 2. Stage 5.

Serum Prestin Level May Increase Following Music Exposure That Induces Temporary Threshold Shifts: A Pilot Study.

To determine if blood prestin level changes after exposure to music at high sound pressure levels, and if this change is associated with temporary threshold shift (TTS) and/or changes in distortion product (DP) amplitude. Participants were exposed to pop-rock music at 100 dBA for 15 min monaurally through headphones. Pure-tone audiometry, DP amplitude, and blood prestin level were measured before and after exposure. Fourteen adults (9 women; age range: 20 to 54 years, median age = 31 [Interquartile ratio = 6.75]) with normal hearing were included in the study. Mean prestin level increased shortly after exposure to music, then returned to baseline within 1 week, although this trend was not observed in all participants. All participants presented TTS or a decrease in DP amplitude in at least one frequency after music exposure. There was a statistically significant average threshold elevation at 4 min postexposure. Statistically significant DP amplitude shifts were observed at 4 and 6 kHz, 2 min following exposure. Mean baseline serum prestin level (mean: 140.00 pg/mL, 95% confidence interval (CI): 125.92 to 154.07) progressively increased following music exposure, reaching a maximum at 2 hr (mean: 158.29 pg/mL, 95% CI: 130.42 to 186.66) and returned to preexposure level at 1 week (mean: 139.18 pg/mL, 95% CI: 114.69 to 163.68). However, after correction for multiple comparisons, mean prestin level showed no statistically significant increase from baseline at any timepoint. No correlation between maximum blood prestin level change and average TTS or distortion product otoacoustic emission amplitude shift was found. However, in an exploratory analysis, TTS at 6 kHz (the frequency at which maximum TTS occurred) decreased significantly as baseline blood prestin level increased. The results suggest that blood prestin level may change after exposure to music at high sound pressure levels, although statistical significance was not reached in this relatively small sample after correction. Baseline serum prestin level may also predict the degree of TTS. These findings thus suggest that the role of baseline serum prestin level as a proxy marker of cochlear susceptibility to intense music exposure should be further explored.

A phase I/IIa safety and efficacy trial of intratympanic gamma-secretase inhibitor as a regenerative drug treatment for sensorineural hearing loss

Inhibition of Notch signalling with a gamma-secretase inhibitor (GSI) induces mammalian hair cell regeneration and partial hearing restoration. In this proof-of-concept Phase I/IIa multiple-ascending dose open-label trial (ISRCTN59733689), adults with mild-moderate sensorineural hearing loss received 3 intratympanic injections of GSI LY3056480, in 1 ear over 2 weeks. Phase I primary outcome was safety and tolerability. Phase lla primary outcome was change from baseline to 12 weeks in average pure-tone air conduction threshold across 2,4,8 kHz. Secondary outcomes included this outcome at 6 weeks and change from baseline to 6 and 12 weeks in pure-tone thresholds at individual frequencies, speech reception thresholds (SRTs), Distortion Product Otoacoustic Emissions (DPOAE) amplitudes, Signal to Noise Ratios (SNRs) and distribution of categories normal, present-abnormal, absent and Hearing Handicap Inventory for Adults/Elderly (HHIA/E). In Phase I (N = 15, 1 site) there were no severe nor serious adverse events. In Phase IIa (N = 44, 3 sites) the average pure-tone threshold across 2,4,8 kHz did not change from baseline to 6 and 12 weeks (estimated change −0.87 dB; 95% CI −2.37 to 0.63; P = 0.252 and −0.46 dB; 95% CI −1.94 to 1.03; P = 0.545, respectively), nor did the means of secondary measures. DPOAE amplitudes, SNRs and distribution of categories did not change from baseline to 6 and 12 weeks, nor did SRTs and HHIA/E scores. Intratympanic delivery of LY3056480 is safe and well-tolerated; the trial’s primary endpoint was not met.

Comparison of Two Clinical Devices for the Measurement of Distortion Product Otoacoustic Emissions in Normal-Hearing Adults.

Otoacoustic emissions (OAEs) are low-intensity sounds generated by the cochlea and associated with the function of the outer hair cells. Since OAE measurements do not require active participation of a listener, OAEs are considered an objective measure of cochlear function. While distortion-product OAEs (DPOAEs) are commonly used in clinical practice, limited information is available on the performance of various clinical devices. This study compared two commercial clinical devices, Titan and Eclipse from Interacoustics, and collected normative data for DPOAEs in people with normal hearing. The data collection and analysis were focused on signal and noise amplitudes as well as signal-to-noise ratios (SNRs). Sixty-three participants with normal hearing (age 23.2±2.0 years) were included in the study. DPOAEs were measured at 31 frequencies ranging from 500 to 10,000 Hz. DPOAE amplitude differed across frequencies. Additionally, a high number of unreliable responses were observed at the edge frequencies (<828 Hz and >6,072 Hz). There were no significant differences between the two devices in terms of DPOAE amplitudes, but the recorded-noise levels (amplitude) differed significantly. SNRs of the recorded OAEs were frequency dependent (higher frequencies showed larger SNRs), and significant differences in terms of SNR were found between the two devices. Despite the above-mentioned differences, the OAEs recorded with both devices met the pass criteria for the SNR (≥6 dB) consistently across frequencies, and thus the differences do not compromise the test outcomes. The frequency dependence of the OAE amplitudes and the corresponding SNRs may be relevant for clinical practice.

Effect of Head Position on Distortion Product Otoacoustic Emissions

Abstract Objectives The study aimed to explore the impact of various head positions on the distortion product otoacoustic emissions (DPOAE) amplitudes, identifying the specific DPOAE frequencies showing the effect was also of interest. Materials and Methods DPOAEs were recorded from the right ears of 50 normal-hearing individuals in six head positions, supine, and five sitting positions (head erect, roll left, roll right, pitch backward, and pitch forward). DPOAEs were averaged and measured for their overall and frequency-specific amplitudes at 1 kHz, 1.5 kHz, 2 kHz, 3 kHz, 4 kHz, 6 kHz, and 8 kHz. Statistical Analysis To investigate the statistical significance of the observed mean differences, the data was tested using repeated measures of analysis of variance (ANOVA) following the Shapiro–Wilk normality test. The pair-wise comparison was tested using the Bonferroni post-hoc test and one-sided Bayesian paired sample t-test. Results The results of ANOVA revealed a significant main effect of head posture only at 1 kHz. The Bonferroni post-hoc test and one-sided Bayesian paired sample t-test results showed significantly higher DPOAE amplitude in the head erect compared to the supine position. There were no significant differences between other pairs of head postures. Conclusion Head posture is a trivial influencing factor of DPOAEs and hence, does not require consideration in interpreting DPOAEs.

Correlation between auditory thresholds and the response amplitude of otoacoustic emissions in post-COVID-19 adults

RESUMO Objetivo: verificar a acuidade auditiva e correlacionar os limiares auditivos da Audiometria Tonal Liminar (ATL) com as Emissões Otoacústicas Evocadas Transientes (EOET) e por Produto de Distorção (EOEPD) em adultos pós-COVID-19. Métodos: estudo transversal, analítico, realizado entre outubro de 2021 e outubro de 2022, com 63 adultos pós-COVID-19 (com faixa etária entre 20-53 anos). Foram realizados: ATL, EOET e EOEPD. Os resultados foram apresentados descritivamente, e utilizou-se o teste de correlação de Spearman. Resultados: não foi identificada perda auditiva. A maioria das bandas de frequências estavam presentes em ambos os exames de emissões. Houve correlação negativa e significante entre os limiares da ATL e EOET nas bandas de frequências de 500-1.500 Hz e 1.500-2.500 Hz à esquerda e entre os limiares da ATL e EOEPD nas bandas de frequências de 1.000, 2.000 e 4.000 Hz à direita, e de 1.000, 2.000, 3.000, 4.000, 6.000 e 8.000 Hz à esquerda. Conclusão: indivíduos adultos pós-COVID-19 apresentaram limiares dentro dos padrões de normalidade, com resposta presente para EOET e EOEPD. Houve correlação negativa entre as EOET e EOEPD e o limiar de via aérea da ATL, indicando que maiores limiares de ATL estão associados a menores amplitudes de resposta das emissões.

Distortion product otoacoustic emissions in newborn babies with and without late-term maternal iron deficiency anaemia

BackgroundStudies on animals have demonstrated that maternal iron deficiency anaemia (IDA) could result in decreased cochlear sensory hair cells and reduced amplitudes of distortion-product otoacoustic emissions (DPOAEs) of young guinea pigs. Thus, it is essential to study the functioning of cochlear hair cells using DPOAEs in human newborn babies with maternal IDA. The current study explores maternal IDA's effect on DPOAEs in newborn babies. MethodA total of 110 newborn babies with gestational age ≥34 weeks were considered and a ‘between-subjects’ design was used. The participants were divided into 3 groups- “Normal” (61 babies without maternal IDA), “Mild” (28 babies with mild maternal IDA) and “Moderate” (21 babies with moderate maternal IDA). The cord blood was collected and the DPOAEs were recorded for each baby for a range of frequencies (1 k – 8 kHz) and a range of intensities (70–40 dB SPL in 10 dB steps). ResultsThe analysis of both DP-gram and DP input-output (I/O) function showed that there was no significant difference (p > 0.05) across the normal, mild, and moderate groups in the overall presence of DPOAEs as well as the amplitude across frequencies or intensities (70–40 dB SPL). Also, the overall correlation of RBC indices with DPOAE amplitude across frequencies as well as the slope of the I/O function showed no relationship. ConclusionThe current study concludes that there is no effect of late-term maternal IDA on the DPOAEs of newborn babies.

Evaluation of Auditory Functions in Patients with Psoriasis.

Our study aims to evaluate the functions of the middle and inner ear and the efferent auditory system in psoriasis. Hearing thresholds, resonance frequency, otoacoustic emission amplitudes with and without contralateral acoustic stimulation, contralateral suppression levels were evaluated in 35 psoriasis patients and 40 controls. The air-conduction hearing thresholds of the patients were significantly higher than the controls at 125, 250, 500, 1000, 2000, 4000, and 12,000Hz frequencies in the left ear, and 125, 250, 500, 1000, 2000, and 4000Hz frequencies in the right ear, and the bone-conduction hearing thresholds of the patients were found to be significantly higher than the controls at all frequencies in the left ear, and 250, 500, 1000 and 2000Hz in the right ear (p < 0.05). The resonance frequencies of patients were found to be significantly lower than the controls (p < 0.001). The emission amplitudes obtained with contralateral acoustic stimulation were significantly lower than without contralateral acoustic stimulation at 1kHz frequency in both groups (p < 0.01). There was no significant difference in contralateral suppression levels of the two groups (p > 0.05). Our findings indicate that middle ear mechanics can be affected by psoriasis. There was no significant difference between psoriasis patients and healthy controls in terms of efferent auditory functions. There was a significant difference at limited frequency in hearing thresholds and emission amplitudes between the groups.

Development of an audiological assessment and diagnostic model for high occupational noise exposure.

To explore the diagnostic auditory indicators of high noise exposure and combine them into a diagnostic model of high noise exposure and possible development of hidden hearing loss (HHL). We recruited 101 young adult subjects and divided them according to noise exposure history into high-risk and low-risk groups. All subjects completed demographic characteristic collection (including age, noise exposure, self-reported hearing status, and headset use) and related hearing examination. The 8kHz (P = 0.039) and 10kHz (P = 0.005) distortion product otoacoustic emission amplitudes (DPOAE) (DPs) in the high-risk group were lower than those in the low-risk group. The amplitudes of the summating potential (SP) (P = 0.017) and action potential (AP) (P = 0.012) of the electrocochleography (ECochG) in the high-risk group were smaller than those in the low-risk group. The auditory brainstem response (ABR) wave III amplitude in the high-risk group was higher than that in the low-risk group. When SNR = -7.5dB (P = 0.030) and -5dB (P = 0.000), the high-risk group had a lower speech discrimination score than that of the low-risk group. The 10kHz DPOAE DP, ABR wave III amplitude and speech discrimination score under noise with SNR = -5dB were combined to construct a combination diagnostic indicator. The area under the ROC curve was 0.804 (95% CI 0.713-0.876), the sensitivity was 80.39%, and the specificity was 68.00%. We expect that high noise exposure can be detected early with this combined diagnostic indicator to prevent HHL or sensorineural hearing loss (SNHL). ChiCTR2200057989, 2022/3/25.

Slight High-Frequency Hearing Loss, Effect of COVID-19 or Hydroxychloroquine Usage?

Background and ObjectivesConcerns about ototoxic and vestibulotoxic effects have been raised with the use of antiviruses in the treatment of COVID-19. This study aimed to determine the effect of hydroxychloroquine (HCQ) and examine the auditory system and its associated auditory and vestibular symptoms in patients with COVID-19.Study DesignProspective study.PatientsThirty patients with a history of HCQ (HCQ+) and 30 patients without drug use (HCQ−), and 30 healthy adults as the control group participated.Main Outcome Measure(s)Audiological assessments and evaluation of audio-vestibular symptoms. Evaluations were also repeated 1 month later.ResultsBoth HCQ+ and HCQ− groups showed poor pure-tone audiometry (PTA) thresholds and decreased transient evoked otoacoustic emission amplitudes at high frequencies in comparison to the healthy group. Despite the lack of significant differences in PTA between the two groups of patients, the differences in transient evoked otoacoustic emission amplitudes were significant. PTA thresholds and otoacoustic emission showed improvement after 1 month. Dizziness was the most common symptom that was reduced after 1 month.ConclusionSlight hearing loss was seen in patients with COVID-19 with or without HCQ. Also, hearing thresholds in the HCQ+ group did not show a significant difference compared with the HCQ− group. Nevertheless, it seems that more damage is done to the hair cells of patients with HCQ intake than in other patients. Hence, the ototoxicity effect of high doses of HCQ use in the COVID-19 patients should be considered. A relative improvement in the hearing was seen over time in both patient groups.

Otoacoustic emission and its application in anesthesia.

An otoacoustic emission (OAE) is a low-level sound emitted by the cochlea. OAEs are able to objectively evaluate the auditory perception and reflect the functional status of the auditory system. With the characteristics of non-invasiveness, high reliability, and easy manipulation, OAEs have gained wide popularity in clinical audiology and anesthesiology. This review aims to summarize the application of OAE in anesthesia. This study collected data from the databases Web of Science-Clarivate Analytics, PubMed, and Google Scholar in English, covering research in the last 40 years. The keywords were defined as anesthesia, cochlea, OAEs, distortion product otoacoustic emissions, transient evoked otoacoustic emissions, bispectral index, auditory evoked potentials, and depth of anesthesia. Documents that matched defined keywords were selected and reviewed. Research showed that the types and doses of anesthetic drugs impacted OAEs. Ketamine-based anesthesia has a greater effect on OAE sensitivity over time compared to isoflurane. A higher dose of ketamine-xylazine significantly reduced the amplitude of OAEs. According to those characteristics, OAEs could be used as an objective evaluation method for the effect of anesthetics and have great potential to be applied for anesthetic drug dose control during surgery. OAEs also have been used to detect the cochlear function during anesthesia, which may cause irreversible damage to the cochlea. Studies reported that OAEs have been used in anesthesia. However, the existing studies have mainly focused on the influence of anesthetic types or dosages on OAEs. Considering the characteristics of OAEs, such as a convenient measurement, less susceptibility to interference, and fast detection speed, the application of OAE has a great potential in the anesthesia field.

Contralateral Suppression of Transient-evoked Otoacoustic Emissions in Leisure Noise Exposed Individuals.

Leisure noise may have a significant impact on hearing thresholds and young adults are often exposed to loud music during leisure activities. This behavior puts them at risk of developing noise-induced hearing loss (NIHL). A frequent initial indication of NIHL is reduced hearing acuity at 4 kHz. The objective of the current study was to assess the role of the medial olivocochlear reflex (MOCR) in leisure noise-exposed individuals with and without a 4-kHz notch. Audiological evaluation, including pure-tone and immittance audiometry, was performed for 156 college-going, young adults between May 2019 to December 2019. All participants had averaged pure-tone audiometric thresholds within normal limits, bilaterally. Annual individual exposure to personal listening devices (PLDs) was calculated using the Noise Exposure Questionnaire. The participants were then categorized into exposed (with and without audiometric 4 kHz notch) and nonexposed groups. Transient-evoked otoacoustic emission amplitude and its contralateral suppression were measured using linear and nonlinear click stimuli to study the effect of leisure noise exposure on MOCR. A significantly reduced overall contralateral suppression effect in participants exposed to PLD usage (P = 0.01) in both linear and nonlinear modes. On the contrary, significantly increased suppression was observed in linear mode for the 4 kHz frequency band in the PLD-exposed group without an audiometric notch (P = 0.009), possibly suggesting an early biomarker of NIHL. Measuring contralateral suppression of otoacoustic emissions may be an effective tool to detect early NIHL in leisure noise-exposed individuals.

The effect of increase in blood glucose level on hearing loss

ObjectivePrevious studies have shown that hearing function is also vulnerable to the effects of diabetes mellitus which can be shown by brainstem auditory evoked potential and distortion product otoacoustic emission recordings. This study aimed to investigate the changes of brainstem auditory evoked potential and distortion product otoacoustic emission in hyperglycemia and whether there is a relationship between reactive oxygen substances production and hearing deterioration in the rat model. Methods25 streptozotocin induced diabetic rats were divided into three groups: control, high blood glucose, and diabetes mellitus. Brainstem auditory evoked potential and distortion product otoacoustic emission were recorded, and thiobarbituric acid reactive substances levels were measured in the brainstem tissue. ResultsAt 8 kHz, the latencies of I, II, III, IV, and V brainstem auditory evoked potential waves in high blood glucose and diabetes mellitus groups were elongated, at 16 kHz, only these wave latencies of the diabetes mellitus group were prolonged compared with the control group. A significant decrease was also found in distortion product otoacoustic emission amplitudes at 4, 6, 8, and 10 kHz in the high blood glucose and diabetes mellitus groups compared to the control group. There was a significant increase in thiobarbituric acid reactive substances values due to the increase in blood glucose levels in the high blood glucose and diabetes mellitus groups compared to the control group. ConclusionThese results suggested that high blood glucose levels may cause hearing impairment not only in the diabetic state but also in the period of hyperglycemia before the onset of manifest diabetes mellitus and reactive oxygen substances may play an important role in the pathophysiology of diabetes mellitus. We suggest that regulating high glucose levels even before the onset of manifest diabetes mellitus may prevent hazardous effects on hearing function. Level of evidenceLevel 3.

Detection of middle-ear muscle reflex activation using changes in otoacoustic emission stimulus amplitude versus absorbance: an initial investigation

Objectives The medial olivocochlear reflex (MOCR) reduces cochlear amplifier gain, which may be beneficial for hearing in noise. Additionally, measurement of the MOCR may be diagnostically useful in the audiology clinic. The MOCR can be measured as the change in transient-evoked otoacoustic emission (TEOAE) amplitude without versus with contralateral acoustic stimulation (CAS). However, CAS can activate the middle-ear muscle reflex (MEMR) which can confound the MOCR results. MEMR activation has been assessed using changes in TEOAE stimulus amplitude without versus with CAS. As an initial investigation, the current study compared detection of MEMR activation using changes in TEOAE stimulus amplitude to changes in wideband absorbance. Methods In 26 normal-hearing participants, the MEMR was measured as the change in absorbance and as the change in TEOAE stimulus amplitude without and with CAS. Percentile critical differences were developed from the test-retest measurements. Measures of agreement between MEMR detection methods were computed. Results CAS resulted in a larger number of participants exceeding the 95th percentile critical difference for absorbance compared to TEOAE stimulus amplitude (22 versus 1). Agreement between methods was low. Conclusion Initial results indicated that MEMR was detectable in a larger number of participants when using absorbance compared to TEOAE stimulus amplitude. However, future work could better equate the two methods and include measurement of MEMR thresholds to determine optimal methods for detecting MEMR activation during MOCR assessments.

Is there any difference in hearing function between surgical and natural menopause?

ABSTRACT This study was designed to examine cochlear function in surgical postmenopausal women and natural menopause. Three groups, each including 20 patients, were formed: surgical menopause (SM), natural menopause (NM), and healthy controls who had not yet gone through menopause. Conventional audiometry (0.125–8 kHz), ultra-high frequency audiometry (10–16 kHz), and otoacoustic emission (OAE) tests were used in the evaluation of the patients. Almost all the hearing thresholds were significantly poorer in the menopause groups than in the control group (p < .05). However, the amplitudes of the healthy controls were higher in transient evoked otoacoustic emissions (TEOAEs), especially in many frequencies of distortion product otoacoustic emissions (DPOAEs) (p < .05). In the SM group, all the frequencies between 0.125 and 10 kHz for the right ear, and 1, 2, 6 and 8 kHz air-conduction hearing thresholds for the left ear were significantly poorer compared to the NM group (p < .05). There was also a significant decrease in the 4, 6, and 8 kHz DPOAE amplitudes of the SM group compared to the NM group (p < .05). This study showed that postmenopausal women, in particular those with SM had significantly poorer hearing thresholds and lower OAE amplitudes. Menopause may be a potential risk factor for the development of hearing loss in women.