Does SARS-CoV-2 affect cochlear functions in children?

Objectives:

To determine the influence of coronavirus disease-19 (COVID-19) on cochlear tasks of children who had COVID-19 previously, and the relevance among disease seriousness and cochlear involvement by otoacoustic emissions (OAEs).

Methods:

The study included 24 hospitalized children after COVID-19 diagnosis, 23 pediatrics that received outpatient treatment, and 21 children who were without COVID-19 diagnosis as the control group between June 2021 and July 2021. Transient evoked otoacoustic emission (TEOAE), distortion product otoacoustic emission, and contrlateral suppression of otoacoustic emission measurements were carried out for each child. Symptoms of patients, the treatments they received, and the duration of hospitalization of the children in the hospitalized group were recorded.

Results:

The comparison of TEOAE test results under masking showed a considerable difference between 3 groups at 1 kHz (p=0.033) and 4 kHz (p=0.021) frequencies (p<0.05). Distortion product otoacoustic emission test results of hospitalized outpatient and control group showed a statistically significant difference at 2 kHz among themselves (p=0.009).

Conclusion:

Our results suggest that severe acute respiratory syndrome coronavirus-2 may influence the medial olivocochlear system of children and have irreversible effects on the cochlear functions. Early detection of problems that may affect cochlear functions is a special critical task, especially in children, who are a particularly vulnerable group in terms of hearing and related speech problems.

The Impacts of Noise Exposure on the Middle Ear Muscle Reflex in a Veteran Population

PURPOSE

Human studies of noise-induced cochlear synaptopathy using physiological indicators identified in animal models (auditory brainstem response [ABR] Wave I amplitude, envelope following response [EFR], and middle ear muscle reflex [MEMR]) have yielded mixed findings. Differences in the population studied may have contributed to the differing results. For example, due to differences in the intensity level of the noise exposure, noise-induced synaptopathy may be easier to detect in a military Veteran population than in populations with recreational noise exposure. We previously demonstrated a reduction in ABR Wave I amplitude and EFR magnitude for young Veterans with normal audiograms reporting high levels of noise exposure compared to non-Veteran controls. In this article, we expand on the previous analysis in the same population to determine if MEMR magnitude is similarly reduced.

METHOD

Contralateral MEMR growth functions were obtained in 92 young Veterans and non-Veterans with normal audiograms, and the relationship between noise exposure history and MEMR magnitude was assessed. Associations between MEMR magnitude and distortion product otoacoustic emission, EFR, and ABR measurements collected in the same sample were also evaluated.

RESULTS

The results of the statistical analysis, although not conventionally statistically significant, suggest a reduction in mean MEMR magnitude for Veterans reporting high noise exposure compared with non-Veteran controls. In addition, the MEMR appears relatively insensitive to subclinical outer hair cell dysfunction, as measured by distortion product otoacoustic emissions, and is not well correlated with ABR and EFR measurements.

CONCLUSIONS

When combined with our previous ABR and EFR findings in the same population, these results suggest that noise-induced synaptopathy occurs in humans. In addition, the findings indicate that the MEMR may be a good candidate for noninvasive diagnosis of cochlear synaptopathy/deafferentation and that the MEMR may reflect the integrity of different neural populations than the ABR and EFR.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.18665645.

Comparison of pure tone audiometry thresholds and transient evoked otoacoustic emissions (TEOAE) of patients with and without Covid-19 pneumonia

Objective

COVID-19 is an infectious disease caused by the new coronavirus that starts similar to an upper respiratory tract infection and causes death by causing pneumonia and vasculopathy. Many viral infections are known to cause hearing loss. In this study, pure-tone audiometry (PTA) thresholds and Transient Evoked Otoacoustic Emissions (TEOAE) results were compared across patients with COVID-19 disease and COVID-19 pneumonia, and control group patients.

Methods

The study included 240 patients in the age range of 18–50 years. The patients were divided into three groups of 80 patients as the control (no disease), COVID-19 (nonpneumonia), Covid-19 (pneumonia) groups. PTA and TEOAE tests were performed on the control group patients and the results were recorded. PTA and TEOAE tests were performed in the COVID-19 groups in the first and third months after the infection ended. Each test was performed twice; the results were recorded, and the mean of the two results was calculated.

Results

PTA results and TEOAE amplitudes in the first and third months were not significantly different between the COVID-19 non-pneumonia group and the control group (p > 0.05), between the COVID-19 pneumonia group and the control group (p > 0.05), and between the COVID-19 non-pneumonia group and the COVID-19 pneumonia group (p > 0.05).

Conclusions

Despite minimal impairment and minimal amplitude decreases in patients, who recovered from COVID-19, such changes were found to become restored in the third month. Furthermore, no significant changes were observed to indicate COVID-19- associated hearing loss.

Link between stimulus otoacoustic emissions fine structure peaks and standing wave resonances in a cochlear model

In response to an external stimulus, the cochlea emits sounds, called stimulus frequency otoacoustic emissions (SFOAEs), at the stimulus frequency. In this article, a three-dimensional computational model of the gerbil cochlea is used to simulate SFOAEs and clarify their generation mechanisms and characteristics. This model includes electromechanical feedback from outer hair cells (OHCs) and cochlear roughness due to spatially random inhomogeneities in the OHC properties. As in the experiments, SFOAE simulations are characterized by a quasiperiodic fine structure and a fast varying phase. Increasing the sound pressure level broadens the peaks and decreases the phase-gradient delay of SFOAEs. A state-space formulation of the model provides a theoretical framework to analyze the link between the fine structure and global modes of the cochlea, which arise as a result of standing wave resonances. The SFOAE fine structure peaks correspond to weakly damped resonant modes because they are observed at the frequencies of nearly unstable modes of the model. Variations of the model parameters that affect the reflection mechanism show that the magnitude and sharpness of the tuning of these peaks are correlated with the modal damping ratio of the nearly unstable modes. The analysis of the model predictions demonstrates that SFOAEs originate from the peak of the traveling wave.

Contralateral noise effects on otoacoustic emissions and electrophysiologic responses in normal-hearing adults

Contralateral noise inhibits the amplitudes of cochlear and neural responses. These measures may hold potential diagnostic utility. The medial olivocochlear (MOC) reflex underlies the inhibition of cochlear responses but the extent to which it contributes to inhibition of neural responses remains unclear. Mertes and Leek [J. Acoust. Soc. Am. 140, 2027-2038 (2016)] recently examined contralateral inhibition of cochlear responses [transient-evoked otoacoustic emissions (TEOAEs)] and neural responses [auditory steady-state responses (ASSRs)] in humans and found that the two measures were not correlated, but potential confounds of older age and hearing loss were present. The current study controlled for these confounds by examining a group of young, normal-hearing adults. Additionally, measurements of the auditory brainstem response (ABR) were obtained. Responses were elicited using clicks with and without contralateral broadband noise. Changes in TEOAE and ASSR magnitude as well as ABR wave V latency were examined. Results indicated that contralateral inhibition of ASSRs was significantly larger than that of TEOAEs and that the two measures were uncorrelated. Additionally, there was no significant change in wave V latency. Results suggest that further work is needed to understand the mechanism underlying contralateral inhibition of the ASSR.

The Spectral Extent of Phasic Suppression of Loudness and Distortion-Product Otoacoustic Emissions by Infrasound and Low-Frequency Tones

We investigated the effect of a biasing tone close to 5, 15, or 30 Hz on the response to higher-frequency probe tones, behaviorally, and by measuring distortion-product otoacoustic emissions (DPOAEs). The amplitude of the biasing tone was adjusted for criterion suppression of cubic DPOAE elicited by probe tones presented between 0.7 and 8 kHz, or criterion loudness suppression of a train of tone-pip probes in the range 0.125–8 kHz. For DPOAEs, the biasing-tone level for criterion suppression increased with probe-tone frequency by 8–9 dB/octave, consistent with an apex-to-base gradient of biasing-tone-induced basilar membrane displacement, as we verified by computational simulation. In contrast, the biasing-tone level for criterion loudness suppression increased with probe frequency by only 1–3 dB/octave, reminiscent of previously published data on low-side suppression of auditory nerve responses to characteristic frequency tones. These slopes were independent of biasing-tone frequency, but the biasing-tone sensation level required for criterion suppression was ~ 10 dB lower for the two infrasound biasing tones than for the 30-Hz biasing tone. On average, biasing-tone sensation levels as low as 5 dB were sufficient to modulate the perception of higher frequency sounds. Our results are relevant for recent debates on perceptual effects of environmental noise with very low-frequency content and might offer insight into the mechanism underlying low-side suppression.

A point-wise artifact rejection method for estimating transient-evoked otoacoustic emissions and their group delay

Due to its low intensity, measurement of transient-evoked otoacoustic emission (TEOAE) requires repeated stimulation. When any acoustic artifact occurs, an entire click interval is typically abandoned. Here, a point-wise artifact rejection strategy is proposed, and it partially preserves the data when artifacts occur in an interval. At the noisiest setting (-46 dB signal-to-noise ratio) the proposed strategy retains four times more data and thereby reduces the root mean square signal estimation error by over 60%. Consequently, the group delay can be calculated more accurately. These findings might facilitate TEOAE measurement at home or in other noisy environments in the future.

Predicting synapse counts in living humans by combining computational models with auditory physiology

Aging, noise exposure, and ototoxic medications lead to cochlear synapse loss in animal models. As cochlear function is highly conserved across mammalian species, synaptopathy likely occurs in humans as well. Synaptopathy is predicted to result in perceptual deficits including tinnitus, hyperacusis, and difficulty understanding speech-in-noise. The lack of a method for diagnosing synaptopathy in living humans hinders studies designed to determine if noise-induced synaptopathy occurs in humans, identify the perceptual consequences of synaptopathy, or test potential drug treatments. Several physiological measures are sensitive to synaptopathy in animal models including auditory brainstem response (ABR) wave I amplitude. However, it is unclear how to translate these measures to synaptopathy diagnosis in humans. This work demonstrates how a human computational model of the auditory periphery, which can predict ABR waveforms and distortion product otoacoustic emissions (DPOAEs), can be used to predict synaptic loss in individual human participants based on their measured DPOAE levels and ABR wave I amplitudes. Lower predicted synapse numbers were associated with advancing age, higher noise exposure history, increased likelihood of tinnitus, and poorer speech-in-noise perception. These findings demonstrate the utility of this modeling approach in predicting synapse counts from physiological data in individual human subjects.

Audiological Features in 63 Patients With Cochlear Nerve Deficiency

OBJECTIVE

We aimed to investigate the clinical features of cochlear nerve deficiency (CND), and in particular, the long-term course of hearing disability and audiogram shapes.

STUDY DESIGN

Retrospective observational nonrandomized group study.

SETTING

Academic medical center.

PATIENTS/INTERVENTIONS

The subjects were 63 children with congenital hearing loss who visited our hospital between 2009 and 2019 and underwent MRI, based on which they were diagnosed with CND. There were 61 cases of unilateral CND and two cases of bilateral CND.

MAIN OUTCOME MEASURES

Imaging tests by MRI and CT and audiometric assessments by pure-tone audiometry and distortion product otoacoustic emission were performed.

RESULTS

Among the cases of CND diagnosed by assessing the cochlear nerve on MRI, approximately 20% of the bony cochlear nerve canals that could be assessed on CT were normal. Of the 61 cases diagnosed with unilateral CND, 55 cases had cochlear nerve aplasia (90.2%), and six had cochlear nerve hypoplasia (9.8%), with a mean hearing ability of 92.2 and 94.6 dB HL, respectively. Thus, the majority of cases had severe-to-profound hearing loss. The overall audiometric patterns were 78.7% flat, 9.8% cookie-bite, and 9.8% high-frequency. Six of 61 cases (9.8%) had a distortion product otoacoustic emission (DPOAE) response based on the affected side, and none of the cases lost the response during follow-up.

CONCLUSIONS

Herein, we report the largest study on CND and performed CND image and audiometric assessments. Accurately in diagnosing CND requires not only CT but also MRI assessment. Hearing loss is often severe to profound; however, various audiometric patterns have been observed. CND includes a small number of cases that respond to DPOAE, indicating that some CND cases are clinically diagnosed with auditory neuropathy spectrum disorder (ANSD). A sustained DPOAE response might help in differentiating CND from other ANSDs. Children with congenital deafness who have passed the newborn hearing screening by DPOAE should be examined by MRI to rule out CND.

Assessment of auditory functions in patients with hepatic glycogen storage diseases

BACKGROUND

Hepatic glycogen storage diseases are a group of diseases manifesting mainly with hypoglycemia and hepatomegaly. The patients require frequent daytime and nocturnal feedings. Hypoglycemia may cause sensorineural hearing loss and nocturnal feeding is a risk factor for the development of gastroesophageal reflux that may cause chronic otitis media and hearing loss consequently. We aimed to determine the prevalence and characteristics of hearing loss in hepatic glycogen storage diseases.

METHODS

A total of 24 patients with hepatic glycogen storage disease (15 glycogen storage disease type I and 9 non type I) and 24 age/sex matched healthy controls were enrolled in the study. Pure tone audiometer, immitansmetry, acoustic reflex measurement, otoacoustic emission test (OAE) and auditory brainstem response (ABR) tests were applied to all participants.

RESULTS

Hearing loss was determined in 17/24 patients (12 glycogen storage disease type I and 5 non type I) with pure tone audiometer. Interpretation of all the findings revealed a total of 8 patients had conductive and 9 had mixed hearing loss. All parameters were significantly different than the control group.

CONCLUSIONS

This is the first study to comprehensively assess the auditory functions of patients with hepatic glycogen storage disease. Audiological findings determined a significantly increased prevalence of conductive/ mixed type hearing loss in the patient group which is a new finding in the literature. Further studies with extended patient numbers are required to enlighten the underlying pathophysiology.

[Auditory neuropathy and prematurity: modern view of the issue (literature review)]

Auditory neuropathy spectrum disorder (ANSD) is a specific auditory disorder caused by dysfunction of periphery part of the auditory system, in which the function of the outer hair cells is preserved, but the afferent input at the cochlear level suffers due to the pathology of the inner hair cells, neurons of the spiral ganglion and/or the auditory nerve, as well as synaptic contact between them. As a result, a specific condition is formed, in which a patient's otoacoustic emissions and/or cochlear microphonics are present, auditory brainstem responses are abnormal or absent, the discrepancy between the hearing level and the electrophysiological data, poor speech perception which may not correlate with the hearing thresholds. ANSD is a multifactorial disease. One of the main risk factors is perinatal pathology and, in particular, prematurity. The possible factors associated with prematurity that provoke the onset of the disease, features of the pathogenesis, clinical and audiological peculiarities of ANSD in premature infants, contemporary approaches to the habilitation of such patients are discussed in the article. The necessity of an individual, patient-oriented approach to the treatment of premature infants with ANSD is substantiated; such an approach should be based both on the genesis of the disorder, taking into account possible points of lesion in the auditory system, and the developmental peculiarities of a premature baby considering the presence of concomitant diseases associated with prematurity. In the article attention is focused on the main directions of habilitation work with such children, including a multidisciplinary approach, regular careful monitoring of the auditory, speech and language skills, intensive psychological and speech therapist support, the choice of an adequate way of intervention and its improvement as necessary.

Distortion Product Otoacoustic Emission (DPOAE) Growth in Aging Ears with Clinically Normal Behavioral Thresholds

Age-related hearing loss (ARHL) is a devastating public health issue. To successfully address ARHL using existing and future treatments, it is imperative to detect the earliest signs of age-related auditory decline and understand the mechanisms driving it. Here, we explore early signs of age-related auditory decline by characterizing cochlear function in 199 ears aged 10-65 years, all of which had clinically defined normal hearing (i.e., behavioral thresholds ≤ 25 dB HL from .25 to 8 kHz bilaterally) and no history of noise exposure. We characterized cochlear function by measuring behavioral thresholds in two paradigms (traditional audiometric thresholds from .25 to 8 kHz and Békésy tracking thresholds from .125 to 20 kHz) and distortion product otoacoustic emission (DPOAE) growth functions at f₂ = 2, 4, and 8 kHz. Behavioral thresholds through a standard clinical frequency range (up to 8 kHz) showed statistically, but not clinically, significant declines across increasing decades of life. In contrast, DPOAE growth measured in the same frequency range showed clear declines as early 30 years of age, particularly across moderate stimulus levels (L₂ = 25-45 dB SPL). These substantial declines in DPOAE growth were not fully explained by differences in behavioral thresholds measured in the same frequency region. Additionally, high-frequency Békésy tracking thresholds above ~11.2 kHz showed frank declines with increasing age. Collectively, these results suggest that early age-related cochlear decline (1) begins as early as the third or fourth decade of life, (2) is greatest in the cochlear base but apparent through the length of the cochlear partition, (3) cannot be detected fully by traditional clinical measures, and (4) is likely due to a complex mix of etiologies.

The effect of caffeine on tinnitus: Randomized triple-blind placebo-controlled clinical trial

Objective

To test the hypothesis that caffeine can influence tinnitus, we recruited 80 patients with chronic tinnitus and randomly allocated them into two groups (caffeine and placebo) to analyze the self-perception of tinnitus symptoms after caffeine consumption, assuming that this is an adequate sample for generalization.

Methods

The participants were randomized into two groups: one group was administered a 300-mg capsule of caffeine, and the other group was given a placebo capsule (cornstarch). A diet that restricted caffeine consumption for 24 hours was implemented. The participants answered questionnaires (the Tinnitus Handicap Inventory—THI, the Visual Analog Scale—VAS, the profile of mood state—POMS) and underwent examinations (tonal and high frequency audiometry, acufenometry (frequency measure; intensity measure and the minimum level of tinnitus masking), transient otoacoustic emissions—TEOAE and distortion product otoacoustic emissions—DPOAE assessments) at two timepoints: at baseline and after capsule ingestion.

Results

There was a significant change in mood (measured by the POMS) after caffeine consumption. The THI and VAS scores were improved at the second timepoint in both groups. The audiometry assessment showed a significant difference in some frequencies between baseline and follow-up measurements in both groups, but these differences were not clinically relevant. Similar findings were observed for the amplitude and signal-to-noise ratio in the TEOAE and DPOAE measurements.

Conclusions

Caffeine (300 mg) did not significantly alter the psychoacoustic measures, electroacoustic measures or the tinnitus-related degree of discomfort.

Examining the Factors that Contribute to Non-Monotonic Growth of the [Formula: see text] Otoacoustic Emission in Humans

Cubic distortion product otoacoustic emission input-output functions in humans show a complex pattern of growth. To further investigate the growth of the [Formula: see text] otoacoustic emission, magnitude and phase input-output functions were obtained from human subjects using a range of stimulus levels, frequencies, and frequency ratios. Three factors related to cochlear nonlinearity may produce non-monotonic input-output functions: a two-component interaction, an operating point shift, and two-tone suppression. To complement data interpretation, a local model of distortion product otoacoustic emission generation was fit to the magnitude spectrum of the averaged ear canal sound pressure recording to quantify operating point shift. Results obtained are consistent with non-monotonic growth occurring primarily as a result of two-tone suppression and/or a two-component interaction. These two mechanisms are expected to operate at different stimulus levels, with different signature magnitude and phase patterns, and are unlikely to overlap in producing non-monotonic growth. An operating point shift was suggested in three cases. These results support multiple factors contributing to the complexity of growth of the [Formula: see text] otoacoustic emission in humans and highlight the importance of looking at phase in addition to magnitude when interpreting distortion product otoacoustic emission growth.

Ultrasonic bone removal from the ossicular chain affects cochlear structure and function

INTRODUCTION

Ultrasonic bone removal devices (UBD) are capable of cutting through bony tissue without injury to adjacent soft tissue. The feasibility and safety of using this technology for removal of bone from an intact ossicular chain (as might be required for otosclerosis or congenital fixation) was investigated in an animal model.

METHODS

This was a prospective animal study conducted on seven anesthetised adult chinchillas. An UBD was used to remove bone from the malleus head in situ. Pre and post-operative distortion product otoacoustic emission (DPOAE) levels and auditory brainstem response (ABR) thresholds were recorded. Scanning electron microscopy (SEM) was used to assess cochlear haircell integrity.

RESULTS

Precise removal of a small quantity of bone from the malleus head was achieved by a 30s application of UBD without disruption of the ossicular chain or tympanic membrane. DPOAEs became undetectable after the intervention with signal-to-noise ratios (SNR) < 5 dB SPL in all ears. Furthermore, ABR thresholds were elevated > 85 dB SPL in 13 ears. SEM showed significant disruption of structural integrity of the organ of Corti, specifically loss and damage of outer haircells.

CONCLUSIONS

Although UBD can be used to reshape an ossicle without middle ear injury, prolonged contact with the ossicular chain can cause structural and functional injury to the cochlea. Extensive cochlea pathology was found, but we did not investigate for recovery from any temporary threshold shift. In the authors' opinion, further study should be undertaken before consideration is given to use of the device for release of ossicular fixation.

COVID-19 and Tinnitus

Coronavirus disease 2019 (COVID-19) is an infectious respiratory disease caused by the severe acute respiratory syndrome coronavirus 2, brings with it a plethora of health concerns. Although most people have mild symptoms, which are respiratory in nature, some experience neurological symptoms, central nervous system manifestations, peripheral nervous manifestations, and skeletal muscle manifestations. But the damaging impact of COVID-19 virus on the hearing organs in the inner ear is a new finding yet to be explored. Currently, there is little evidence published connecting novel coronavirus and tinnitus directly. But according to the American Tinnitus Association, preexisting behavioral conditions make it more likely for patients to experience tinnitus due to the stress and depression associated with social isolation and infection avoidance. Hearing loss and Tinnitus is a common pathology seen in otolaryngology and there are numerous papers in literature describing its associations with other infections. However, this is the first reported case of hearing loss and tinnitus in a COVID-19 patient, in the State of Qatar, and this case report strives to contribute to the ocean of literature highlighting the need for otorhinolaryngologists to be aware of its correlation with COVID-19 virus.

Results of a Government-supported Newborn Hearing Screening Pilot Project in the 17 Cities and Provinces from 2014 to 2018 in Korea

BACKGROUND

The aim of this study was to present and analyze, for the first time, the results of a government-supported nationwide newborn hearing screening (NHS) pilot project in the 17 major cities and provinces of Korea.

METHODS

We analyzed a nationwide NHS database of 344,955 newborns in the pilot project from 2014 to 2018. The government supported the cost of one NHS and one diagnostic auditory brainstem response (ABR) test. Hearing loss (HL) was defined as ≥ 40 dB nHL on either side of the ABR threshold test.

RESULTS

Most NHS tests were performed in the maternity clinics (91.5%). In regions with lack of maternity clinics, the screening rate of local clinics was high (Jeju: 31.1% and Sejong: 12.9%). In most regions, automated ABR was mainly used for screening test (89.7%), but Gangwon (32.7%), Jeju (31.0%), and Jeonbuk (29.6%) performed more NHS tests using (automated) otoacoustic emissions than other regions. The mean referral rate was 1.5%, but the overall diagnostic ABR rate was low at 18.5%. The referral rates of Busan (0.6%) and Gyeongnam (0.9%) were lower than 1%, and Jeju's referral rate was 7.3%. Prevalence of HL including unilateral HL was 0.12%.

CONCLUSION

Depending on the cities and provinces, there were significant differences in the screening rates and referral rates by hospital type and NHS method. For successful early hearing detection and intervention (EHDI) and quality control, it will be necessary to support and manage EHDI according to regional NHS's characteristics and ensure that the whole country conducts EHDI as standard.

Absent or Elevated Middle Ear Muscle Reflexes in the Presence of Normal Otoacoustic Emissions: A Universal Finding in 136 Cases of Auditory Neuropathy/Dys-synchrony

We extracted a subpopulation of 136 patients (from our database of 257 AN/AD subjects) in whom middle ear muscle reflexes had been measured. None showed normal reflexes at all frequencies tested. Only three subjects showed any reflexes at 95 dB HL or below, but never at both 1 and 2 kHz in both ears whether ipsilaterally or contralaterally elicited. All the other reflex measures in these remaining 133 patients were either absent or observed above 100 dB HL, which is incongruous with their normal otoacoustic emissions throughout the frequency bands.

Therefore, we urge colleagues to test ipsilateral middle ear muscle reflex at least at 1 kHz and 2 kHz in any perinatal hearing screening that depends solely on otoacoustic emissions. If the emissions are present and the reflexes are absent or elevated, an ABR may be required to properly intervene, because the management of AN/AD patients often differs drastically from what the behavioral audiogram or the ABR suggest.

Differences in Responses from the Cochleae and Central Nervous Systems of Females with Low versus High Acceptable Noise Levels

Studies of acceptable noise level (ANL) consistently report large intersubject variability in acceptance of background noise while listening to speech. This variability is not related to age, gender, hearing sensitivity, type of background noise, speech perception in noise performance, or efferent activity of the medial olivocochlear pathway. An exploratory study was conducted to determine if differences in aggregate responses from the peripheral and central auditory system can account for intersubject variability in ANL. Click-evoked otoacoustic emissions (CEOAEs), binaural auditory brainstem responses (ABRs), and middle latency responses (MLRs) were measured in females with normal hearing with low (n = 6) versus high (n = 7) ANLs. Results of this preliminary study indicate no differences between the groups for CEOAEs or waves I or III of the ABR. Differences between the two groups emerge for the amplitudes of wave V of the ABR and for the Na-Pa component of the MLR, suggesting that physiological variations arising from more central regions of the auditory system may mediate background noise acceptance.

Human Frequency-Following Response Correlates of the Distortion Product at 2F1-F2

We characterized the 2F1-F2 distortion product reflected in the human frequency-following response (FFR). In the first experiment, we evaluated the input-output growth functions of the distortion product at 2F1-F2 (FFR-DP) for three primary pairs. In the second experiment, we tested the effect of primary tone level variation on the FFR-DP. The results for all three stimulus pairs showed that while the amplitude of FFR-DP increased with stimulus intensity, the slope of the amplitude growth decreased with increasing frequency. Consistent with distortion product otoacoustic emission (DPOAE) data, our observations suggest that there is a distinct region where the separation of the primary tone levels produces maximal distortion. The robust FFR-DP measure could complement the less reliable DPOAE at low frequencies and when middle ear pathology precludes its measurement.

Efficacy of the Antioxidant N-acetylcysteine (NAC) in Protecting Ears Exposed to Loud Music

Antioxidants have been reported to be effective in reducing acoustic trauma in animal models but have not been studied in humans. In this study, the antioxidant N-acetylcysteine (NAC) was evaluated to determine if it would reduce temporary changes in auditory function as a result of exposure to loud music in humans. Pure-tone thresholds and distortion product otoacoustic emissions (DPOAEs) were collected in 31 normal-hearing participants, using a randomized, double-blind, placebo-controlled design, before and after two hours of live music in a nightclub. Using repeated measures analysis of variance, no statistically significant differences were found between participants who received NAC versus a placebo for any of the outcome measures. Across all subjects, the largest pure-tone threshold shift occurred at 4 kHz. DPOAE measures were characterized by reductions in amplitude and a trend for shorter group delay values. When the 3 and 4 kHz data were examined by imposing specific criteria of greater than 2 dB DPOAE amplitude reductions and 10 dB or greater pure-tone threshold shifts, DPOAE reductions occurred more often at 3 kHz, and pure-tone shifts occurred more often at 4 kHz.

ABR and DPOAE Indices of Normal Loudness in Children and Adults

Loudness growth prediction using normal templates of loudness derived with ABR and DPOAE measures was investigated in 20 children 4 to 12 years and 20 adults with normal hearing. An ABR click latency-intensity function (LIF), ABR 2 kHz tone LIF, and DPOAE 2 kHz amplitude-intensity function (AIF) were recorded from each listener. A loudness-intensity function was also measured for each electrophysiologic stimulus. Children and adults exhibited similar intensity functions of ABR latency, DPOAE amplitude, and loudness. A statistically significant relationship was found between loudness and ABR latency and DPOAE amplitude. Loudness estimation equations derived with ABR latency and DPOAE amplitude accurately and reliably predicted the loudness-intensity functions of the listeners. Normative ABR and DPOAE templates of predicted loudness growth may have clinical application in site-of-lesion assessment or hearing aid fitting by distinguishing abnormal rates of loudness growth for individuals who cannot provide reliable behavioral measures.

An Evaluation of the Cross-Check Principle Using Visual Reinforcement Audiometry, Otoacoustic Emissions, and Tympanometry

Background: Early intervention to reduce the effects of congenital hearing loss requires accurate description of hearing loss. In pediatric audiology, a cross-check principle is used to compare behavioral and physiological tests.

Purpose: The purpose of this study was to investigate the correspondence of visual reinforcement audiometry (VRA) minimal response levels (MRLs), otoacoustic emissions (OAEs), tympanometry, and VRA test reliability to determine the odds of obtaining the expected cross-check results. We hypothesized that (1) when MRLs were within normal limits (WNL), OAEs would be present; (2) in the event of normal MRLs and absent OAEs, tympanograms would be abnormal; and (3) in the event of elevated MRLs and present OAEs, the tester's confidence in the MRLs would be judged to be only fair, rather than good.

Research Design: This was a retrospective study.

Study Sample: A previous study provided data from 993 infants who had diagnostic audiologic evaluations at 8–12 mo of age.

Data Collection and Analysis: The data were analyzed to compare VRA MRLs with OAE signal-to-noise ratios at 1, 2, and 4 kHz. Odds ratios and 95% confidence intervals were calculated to test the three hypotheses related to the correspondence among MRLs, OAEs, tympanometry, and the reliability of MRLs.

Results: The probability that OAEs would be present when MRLs were WNL varied from 12 to 26 to 1, depending on the test frequency. When OAEs were absent in the presence of normal MRLs, the odds of abnormal tympanometry varied from 5 to 10 to 1, depending on the test frequency. When MRLs were elevated (>20 dB HL), the odds suggested that examiners judged the MRLs at 1 and 2 kHz to lack reliability.

Conclusion: The results suggest that the cross-check principle is effective when employing VRA, OAE, and tympanometry to rule out or determine the degree, type, and configuration of hearing loss in infants.

The effects of hyperinsulinemia on cochlear functions

CONTEXT

Hyperinsulinemia is the most common metabolic change associated with cochleovestibular diseases.

AIM

We aimed to investigate the auditory functions in hyperinsulinemic individuals.

SETTINGS AND DESIGN

A total of 164 patients were included in this case-control study. While 76 patients with insulin resistance (homeostasis model assessment of insulin resistance [HOMA-IR] of ≥2.5) constituted the case group, 88 patients with HOMA-IR values of <2.5 constituted the control group of the study.

MATERIAL AND METHODS

The 75 g oral glucose tolerance test, blood biochemistry tests, hormonal analysis, audiological assessment, electrocochleography (EcochG), and transient evoked otoacoustic emissions (TEOAE) testing were performed.

STATISTICAL ANALYSIS

One-way analysis of variance and Kruskal-Wallis analysis of variance were used for the comparison of the metabolic and ear parameters in the normal glucose tolerance (NGT), impaired fasting glucose (IFG), and impaired glucose tolerance (IGT) groups. The chi-square test was used to compare nominal variables. Spearman and Pearson correlation coefficients were used for the correlation analyses of continuous variables.

RESULTS

The pure tone audiometry at 0.5, 1, 2, and 4 kHz was better in the case group than in the control group. A positive correlation was found between HbA1c and right ear 0.5, 1, 4, and 8 kHz threshold values and left ear 2, 4, 6, and 8 kHz threshold values. A negative correlation was found between HbA1c and speech discrimination scores. The right ear 1.00 and 2.83 kHz TEOAE measurements in the individuals with NGT were found higher than those in patients with IGT, and the 1.42 kHz TEOAE measurements and reproducibility were found higher than those in patients with IFG. The left ear 1.00 and 1.42 kHz TEOAE measurements of the IGT patients were found lower than those of IFG and NGT patients.

CONCLUSION

We showed that hearing was worsening in hyperinsulinemic patients and prediabetic conditions were related to hearing function impairment.

Detection of Age-Related Hearing Losses (ARHL) via Transient-Evoked Otoacoustic Emissions

PURPOSE

The objective of the study was to identify subjects presenting hearing deficits, specifically age-related hearing losses (ARHL), via objective assessment methodologies.

MATERIALS AND METHODS

Initially, 259 subjects (165 men, 94 women) were enrolled in the study. After the application of inclusion criteria, the final number was reduced to 88 subjects (49.8 ± 19.1 ys) subdivided into 64 normal and 83 ARHL cases. The subjects were assessed with traditional audiometry tests and with transiently evoked otoacoustic emissions (TEOAEs). Since each ear has its own acoustic signature, the TEOAE analyses were conducted in terms of ears and not subjects. The TEOAE data were processed by traditional and recurrence quantification analyses, leading to the estimation of the WWR (whole waveform reproducibility) and the new RAD2D (2-dimensional radius) parameters. A plot of WWR vs RAD2D was used to optimize the classification of the cases presenting ARHL.

RESULTS

By using a WWR value of 70% as a classifier, the sensitivity of TEOAEs was estimated as 75.9% and the specificity as 89.1%. By using the RAD2D parameter (with a cut-off value of 1.78), a sensitivity value of 80.7% and a specificity value of 71.9% were obtained. When both parameters were used, a sensitivity value of 85.5% and a specificity value of 92.2% were estimated. In the latter classification paradigm, the number of false negatives decreased from 20 to 12 out of 83 ears (14%).

CONCLUSION

In adult hearing screening assessments, the proposed method optimizes the identification of subjects with a hearing impairment correlated to the presence of age-related hearing loss.

Examining the Early Period Effect of Nilotinib on Hearing: An Experimental Study

OBJECTIVES

Nilotinib has very few side effects, including neutropenia, thrombocytopenia, cardiotoxicity, high pancreatic lipase, ischemia, and vascular occlusion. We aimed to investigate whether short-term administration of nilotinib had ototoxic effects in rats.

MATERIALS AND METHODS

Wistar-albino rats were categorized into three groups: group C (administered 0.25 mL of distilled water, no nilotinib), group N-20 (administered 20 mg/kg/day of nilotinib dissolved in distilled water), and group N-50 (administered 50 mg/kg/day of nilotinib dissolved in distilled water). A single dose was administered once per day, at the same hour, over 21 days. Auditory brainstem response (ABR) thresholds were recorded on day 0 and day 21.

RESULTS

There were no changes in ABR threshold values obtained on day 0 (baseline) and on day 21 across all three groups. A statistically significant difference was not found in terms of the mean latency of waves V and III, interpeak latency values of waves III-V, and amplitude ratios of waves III-V and V/Va at baseline and on day 21 across all three groups on within-group or between-group evaluation.

CONCLUSION

Consequently, further studies are needed that involve different drug doses, prolonged administration of drugs, as well as distortion otoacoustic emission test for the evaluation of cochlear activation and ABR. Furthermore, histopathological studies are needed to indicate whether the cochlea is affected to prove that nilotinib has definitively no ototoxic effect.

Assessment of Hidden Hearing Loss in Normal Hearing Individuals with and Without Tinnitus

OBJECTIVES

To evaluate the functions of cochlear structures and the distal part of auditory nerve as well as dead regions within the cochlea in individuals with normal hearing with or without tinnitus by using electrophysiological tests.

MATERIALS AND METHODS

Nine individuals (ages: 21-59 years) with normal hearing with tinnitus were included in the study group. Thirteen individuals (ages: 25-60 years) with normal hearing without tinnitus were included in the control group. Immitancemetric examination, pure-tone audiometry (125Hz-16kHz), speech audiometry in quiet and noise environments, transient evoked otoacoustic emissions (TEOAEs), distortion product otoacoustic emissions (DPOAEs), threshold equalizing noise (TEN test (500Hz-4kHz), and ECochG tests, Beck Depression Questionnaire, Tinnitus Handicap Questionnaire, and Visual Analog Scale were performed.

RESULTS

In the study group, three patients were found to have a minimal depression and six were found to have a mild depression. In pure-tone audiometry, the threshold (6-16 kHz) in the study group was significantly higher than that of the control group at all frequencies. In the study group, lower performance scores were obtained in speech discrimination in noise in both ears. In the control group, no dead region was detected in the TEN test whereas 75% of subjects in the study group had dead regions. DPOAE and TEOAE responses between study and control group subjects were not different. In the ECochG test, subjects in the study group showed an increase in the summating potential/action potential (SP/AP) ratio in both ears.

CONCLUSION

Determination of the SP/AP ratio in patients with tinnitus may be useful in diagnosing hidden hearing loss. Detection of dead regions in 75% of patients in the TEN test may indicate that inner hair cells may be responsible for tinnitus.

Postnatal Effects of Sex Hormones on Click-Evoked Otoacoustic Emissions: A Study of Adolescents with Gender Dysphoria

Click-evoked otoacoustic emissions (CEOAEs) are echo-like sounds, generated by the inner ear in response to click-stimuli. A sex difference in emission strength is observed in neonates and adults, with weaker CEOAE amplitudes in males. These differences are assumed to originate from testosterone influences during prenatal male sexual differentiation and to remain stable throughout life. However, recent studies suggested activational, postnatal effects of sex hormones on CEOAEs. Adolescents diagnosed with gender dysphoria (GD) may receive gonadotropin-releasing hormone analogs (GnRHa) in order to suppress endogenous sex hormones and, therefore, pubertal maturation, followed by cross-sex hormone (CSH) treatment. Using a cross-sectional design, we examined whether hormonal interventions in adolescents diagnosed with GD (62 trans boys, assigned female at birth, self-identifying as male; 43 trans girls, assigned male at birth, self-identifying as female), affected their CEOAEs compared to age- and sex-matched controls (44 boys, 37 girls). Sex-typical differences in CEOAE amplitude were observed among cisgender controls and treatment-naïve trans boys but not in other groups with GD. Treatment-naïve trans girls tended to have more female-typical CEOAEs, suggesting hypomasculinized early sexual differentiation, in support of a prominent hypothesis on the etiology of GD. In line with the predicted suppressive effects of androgens, trans boys receiving CSH treatment, i.e., testosterone plus GnRHa, showed significantly weaker right-ear CEOAEs compared with control girls. A similar trend was seen in trans boys treated with GnRHa only. Unexpectedly, trans girls showed CEOAE masculinization with addition of estradiol. Our findings show that CEOAEs may not be used as an unequivocal measure of prenatal androgen exposure as they can be modulated postnatally by sex hormones, in the form of hormonal treatment.

Evidence supporting synchrony between two active ears due to interaural coupling

Motivated by recent developments suggesting that interaural coupling in non-mammals allows for the two active ears to effectively synchronize, this report describes otoacoustic measurements made in the oral cavity of lizards. As expected from that model, spontaneous otoacoustic emissions (SOAEs) were readily measurable in the mouth, which is contiguous with the interaural airspace. Additionally, finite element model calculations were made to simulate the interaural acoustics based upon SOAE-related tympanic membrane vibrational data. Taken together, these data support the notion of two active ears synchronizing by virtue of acoustic coupling and have potential implications for sound localization at low-levels.

Systematic Audiological Assessment of Auditory Functioning in Patients With Parkinson's Disease

Purpose Alterations in primary auditory functioning have been reported in patients with Parkinson's disease (PD). Despite the current findings, the pathophysiological mechanisms underlying these alterations remain unclear, and the effect of dopaminergic medication on auditory functioning in PD has been explored insufficiently. Therefore, this study aimed to systematically investigate primary auditory functioning in patients with PD by using both subjective and objective audiological measurements. Method In this case-control study, 25 patients with PD and 25 age-, gender-, and education-matched healthy controls underwent an audiological test battery consisting of tonal audiometry, short increment sensitivity index, otoacoustic emissions (OAEs), and speech audiometry. Patients with PD were tested in the on- and off-medication states. Results Increased OAE amplitudes were found when patients with PD were tested without dopaminergic medication. In addition, speech audiometry in silence and multitalker babble noise demonstrated higher phoneme scores for patients with PD in the off-medication condition. The results showed no differences in auditory functioning between patients with PD in the on-medication condition and healthy controls. No effect of disease stage or motor score was evident. Conclusions This study provides evidence for a top-down involvement in auditory processing in PD at both central and peripheral levels. Most important, the increase in OAE amplitude in the off-medication condition in PD is hypothesized to be linked to a dysfunction of the olivocochlear efferent system, which is known to have an inhibitory effect on outer hair cell functioning. Future studies may clarify whether OAEs may facilitate an early diagnosis of PD.

Comparison of distortion-product otoacoustic emission and stimulus-frequency otoacoustic emission two-tone suppression in humans

Distortion-product otoacoustic emission (DPOAE) and stimulus-frequency otoacoustic emission (SFOAE) are two types of acoustic signals emitted by the inner ear in response to tonal stimuli. The levels of both emission types may be reduced by the inclusion of additional (suppressor) tones with the stimulus. Comparison of two-tone suppression properties across emission type addresses a clinically relevant question of whether these two types of emission provide similar information about cochlear status. The purpose of this study was to compare DPOAE suppression to SFOAE suppression from the same ear in a group of participants with normal hearing. Probe frequency was approximately 1000 Hz, and the suppressor frequency varied from -1.5 to 0.5 octaves relative to the probe frequency. DPOAE and SFOAE suppression were compared in terms of (1) suppression growth rate (SGR), (2) superimposed suppression tuning curves (STCs), and (3) STC-derived metrics, such as high-frequency slope, cochlear amplifier gain, and Q_ERB (ERB, equivalent rectangular bandwidth). Below the probe frequency, the SGR was slightly greater than one for SFOAEs and slightly less than two for DPOAEs. There were no differences in STC metrics across emission types. These observations may provide useful constraints on physiology-based models of otoacoustic emission suppression.

Case report: Novel GJB2 variant c.113T>C associated with autosomal recessive non-syndromic hearing loss (ARNSHL) in a Han family

RATIONALE

Molecular mechanism underlying the autosomal recessive non-syndromic hearing loss (ARNSHL) is still plausible. Pathogenic mutations of the gap junction beta 2 protein (GJB2) are reported to be the primary causes of ARNSHL.

PATIENT CONCERNS

A propositus was diagnosed as ARNSHL with bilateral congenital profound hearing loss.

DIAGNOSIS

With microarray and target gene sequencing testing methods, a novel GJB2 mutant was found to be associated with ARNSHL in this Han Chinese family.

INTERVENTIONS/OUTCOMES

Based on the finding in this research, prenatal screening of GJB2 mutation and genetic counseling are recommended to this family for their next pregnancy. Our interventions allow the family to plan informatively.

LESSONS

In this family, we discovered 2 heterozygous carriers of c.113T>C variation in the GJB2 gene. The propositus, who had profound hearing loss, had inherited the c.113T>C variation from his normal mother and the c.235delC from his father.

Onset kinetics of noise-induced purinergic adaptation of the 'cochlear amplifier'

A major component of slowly reversible hearing loss which develops with sustained exposure to noise has been attributed to release of ATP in the cochlea activating P2X2 receptor (P2X2R) type ATP-gated ion channels. This purinergic humoral adaptation is thought to enable the highly sensitive hearing organ to maintain function with loud sound, protecting the ear from acoustic overstimulation. In the study that established this hearing adaptation mechanism as reported by Housley et al. (Proc Natl Acad Sci U S A 110:7494-7499, 2013), the activation kinetics were determined in mice from auditory brainstem response (ABR) threshold shifts with sustained noise presentation at time points beyond 10 min. The present study was designed to achieve finer resolution of the onset kinetics of purinergic hearing adaptation, and included the use of cubic (2f1-f2) distortion product otoacoustic emissions (DPOAEs) to probe whether the active mechanical outer hair cell 'cochlear amplifier' contributed to this process. We show that the ABR and DPOAE threshold shifts were largely complete within the first 7.5 min of moderate broadband noise (85 dB SPL) in wildtype C57Bl/6J mice. The ABR and DPOAE adaptation rates were both best fitted by a single exponential function with ~ 3 min time constants. ABR and DPOAE threshold shifts with this noise were minimal in mice null for the P2rx2 gene encoding the P2X2R. The findings demonstrate a considerably faster purinergic hearing adaptation to noise than previously appreciated. Moreover, they strongly implicate the outer hair cell as the site of action, as the DPOAEs stem from active cochlear electromotility.

Alterations in hearing function of patients with glucose disorders

OBJECTIVE

To study the prevalence of hearing impairment in patients with various glucose disorders.

PATIENTS AND METHODS

A total of 499 individuals were studied, 51 patients with type 1 (TIDM), 188 patients with type 2 diabetes mellitus (T2DM), 39 patients with impaired fasting glucose (IFG), and 221 controls. Measurements were performed, blood was drawn, and a relevant questionnaire was completed. Ηearing function was assessed by pure-tone audiometry (PTA) and distortion product otoacustic emissions (DPOAEs).

RESULTS

Patients with impaired glucose metabolism (IGM: T2DM or IFG) compared to controls had a higher percentage of abnormal PTA and DPOAEs for both the right (70.2 vs. 56.9% and 40.4 vs. 24.2%, respectively, p < 0.001) and the left (74.1 vs. 59.3% and 47.5 vs. 25.4%, respectively, p < 0.001) ear. Patients with TIDM had similar levels for the left ear (54.9 vs. 59.3% and 27.5 vs. 25.4%, respectively, p > 0.05) and lower levels for the right ear (35.3 vs. 56.9% and 13.7 vs. 24.2%, respectively, p < 0.001 and p = 0.044) percentages of abnormal PTA and DPOAEs compared to controls. Logistic regression analysis indicated that independent parameters for abnormal DPOAEs in one or both ears are age, male gender, exposure to noisy environments, and the presence of IGM.

CONCLUSIONS

Hearing impairment was more prevalent in patients with IGM compared to healthy controls, as assessed by PTA and DPOAEs. Age, male gender, and exposure to noise are other factors that can independently affect hearing ability. Physicians should bear in mind possible defects in hearing ability when dealing with such patients.

Longitudinal Development of Wideband Absorbance and Admittance Through Infancy

Purpose The aim of this article was to study the normal longitudinal development of wideband absorbance and admittance measures through infancy. Method Two hundred one infants who passed the newborn hearing screen (automated auditory brainstem response) were tested at birth and then followed up at approximately 6, 12, and 18 months of age. Most infants were of either White (86%) or Asian (11%) descent. At each test session, infants passed tympanometry and distortion product otoacoustic emission tests. High-frequency (1000-Hz) tympanometry was used at birth and 6 months of age, and low-frequency (226-Hz) tympanometry was used at 12 and 18 months of age. Wideband pressure reflectance was also measured at each session and analyzed in terms of absorbance, admittance at the probe tip, and admittance normalized for differences in ear canal area. Multilevel hierarchical models were fitted to the absorbance and admittance data to investigate for effects of age, ear side, gender, ethnicity, and frequency. Results There were considerable age effects on wideband absorbance and admittance measurements over the first 18 months of life. The most dramatic changes occurred between birth and 6 months of age, and there were significant differences between all age groups in the 3000- to 4000-Hz region. There were significant ethnicity effects that were substantial for certain combinations of ethnicity, age, and frequency (e.g., absorbance at 6000 Hz at 12 months of age). Conclusion There are large developmental effects on wideband absorbance and admittance measures through infancy. For absorbance, we recommend separate reference data be used at birth, 6 months of age, and 12-18 months of age. For admittance (both normalized and at the probe tip), we advise using separate normative regions for each age group (neonates and 6, 12, and 18 months).

Audiologic and Otologic Complications of Cryptococcal Meningoencephalitis in Non-HIV Previously Healthy Patients

OBJECTIVE

To identify audiologic and otologic outcomes in previously healthy non-HIV patients with cryptococcal meningoencephalitis (CM).

STUDY DESIGN

Retrospective case review of a subset of patients recruited in a prospective observational study following previously healthy individuals who developed CM.

SETTING

Tertiary referral center, National Institutes of Health Clinical Center.

PATIENTS

Previously healthy adult patients with CM without immune suppressive therapy before disease onset.

INTERVENTIONS

Diagnostic evaluations included audiometry, acoustic immittance, otoacoustic emissions, and auditory brainstem response studies, in addition to neurotologic assessment.

RESULTS

Twenty-nine patients (58 years) underwent audiologic evaluation between 6 months and 3.5 years after CM diagnosis; 21 patients were seen for longitudinal assessment with an average duration of follow up of 20.3 months. Nearly three-quarters (73%) of the cohort presented with hearing loss, most commonly (90%) sensorineural in origin. The most frequent degree of loss was mild and then moderate, although some patients had severe or profound impairment. Hearing loss improved (43%) or remained stable (38%) in most cases. Ears with internal auditory canal enhancement on magnetic resonance imaging (MRI) had significantly more hearing loss than those without enhancement, although a similar finding was not observed with gyral enhancement or the presence of ependymitis or ventricular volume expansion. Hearing loss was not associated with reduced cerebrospinal fluid (CSF) glucose, CSF total protein, cryptococcal antigen, or total cell count.

CONCLUSIONS

Hearing loss is a common manifestation of cryptococcal meningitis in previously healthy patients and may involve a cochlear or neural site of lesion, or both. Routine surveillance of hearing in patients is recommended, regardless of symptomatology, to ensure early and appropriate intervention and care.

Effects of selective auditory-nerve damage on the behavioral audiogram and temporal integration in the budgerigar

Auditory-nerve fibers are lost steadily with age and as a possible consequence of noise-induced glutamate excitotoxicity. Auditory-nerve loss in the absence of other cochlear pathologies is thought to be undetectable with a pure-tone audiogram while degrading real-world speech perception (hidden hearing loss). Perceptual deficits remain unclear, however, due in part to the limited behavioral capacity of existing rodent models to discriminate complex sounds. The budgerigar is an avian vocal learner with human-like behavioral sensitivity to many simple and complex sounds and the capacity to mimic speech. Previous studies in this species show that intracochlear kainic-acid infusion reduces wave 1 of the auditory brainstem response by 40-70%, consistent with substantial excitotoxic auditory-nerve damage. The present study used operant-conditioning procedures in trained budgerigars to quantify kainic-acid effects on tone detection across frequency (0.25-8 kHz; the audiogram) and as a function of duration (20-160 ms; temporal integration). Tone thresholds in control animals were lowest from 1 to 4 kHz and decreased with increasing duration as in previous studies of the budgerigar. Behavioral results in kainic-acid-exposed animals were as sensitive as in controls, suggesting preservation of the audiogram and temporal integration despite auditory-nerve loss associated with up to 70% wave 1 reduction. Distortion-product otoacoustic emissions were also preserved in kainic-acid exposed animals, consistent with normal hair-cell function. These results highlight considerable perceptual resistance of tone-detection performance with selective auditory-nerve loss. Future behavioral studies in budgerigars with auditory-nerve damage can use complex speech-like stimuli to help clarify aspects of auditory perception impacted by this common cochlear pathology.

The Effect of Short-Term Noise Exposure on Audiometric Thresholds, Distortion Product Otoacoustic Emissions, and Electrocochleography

Purpose The purpose of the study was to examine the effect of short-term noise exposure on audiometric thresholds, distortion product otoacoustic emissions (DPOAEs), and electrocochleography (ECochG) as a function of ear and sex. Method Preexposure and postexposure measures of audiometric thresholds, DPOAEs, and ECochG indices were examined. Sixteen male and 16 female adults participated. Participants were exposed to a 2000-Hz narrowband noise presented at 105 dBA for 10 min. Results Following noise exposure, significantly ( p < .0001) larger auditory threshold differences were observed for left ears. Larger auditory threshold differences were also observed for 3000 and 4000 Hz versus 2000 and 6000 Hz. DPOAE absolute amplitude differences increased with decreasing L ₁, L ₂ level ( p < .0001). DPOAE absolute amplitude differences also significantly rose with increasing f₂ frequencies ( p < .0001). Females generally had larger DPOAE absolute amplitude differences than males ( p < .05). Summating potential amplitudes were significantly larger for female left ears following noise exposure ( p = .03). Left-ear summating potential/action potential amplitude ratios and summating potential/action potential area ratios were increased following noise exposure ( p < .05). Conclusions Utilizing a test battery to examine the effects of short-term noise exposure can reveal the functional status of different structures in the cochlea. There appears to be a susceptibility of the left ear to short-term loud noise exposure. Findings with respect to a sex susceptibility to short-term loud noise exposure were not strong, as sex differences were only observed for a subset of the conditions.

Oscillatory infrasonic modulation of the cochlear amplifier by selective attention

Evidence shows that selective attention to visual stimuli modulates the gain of cochlear responses, probably through auditory-cortex descending pathways. At the cerebral cortex level, amplitude and phase changes of neural oscillations have been proposed as a correlate of selective attention. However, whether sensory receptors are also influenced by the oscillatory network during attention tasks remains unknown. Here, we searched for oscillatory attention-related activity at the cochlear receptor level in humans. We used an alternating visual/auditory selective attention task and measured electroencephalographic activity simultaneously to distortion product otoacoustic emissions (a measure of cochlear receptor-cell activity). In order to search for cochlear oscillatory activity, the otoacoustic emission signal, was included as an additional channel in the electroencephalogram analyses. This method allowed us to evaluate dynamic changes in cochlear oscillations within the same range of frequencies (1–35 Hz) in which cognitive effects are commonly observed in electroencephalogram works. We found the presence of low frequency (<10 Hz) brain and cochlear amplifier oscillations during selective attention to visual and auditory stimuli. Notably, switching between auditory and visual attention modulates the amplitude and the temporal order of brain and inner ear oscillations. These results extend the role of the oscillatory activity network during cognition in neural systems to the receptor level.

Oto-acoustic emissions and brainstem evoked response audiometry in patients of tinnitus with normal hearing

INTRODUCTION

Tinnitus is defined as the perception of sound that results completely from activity within the nervous system without any corresponding mechanical, vibratory activity within the cochlea, and not related to external stimulation of any kind. It disrupts the daily life of 1 out of every 200 adults. The source of tinnitus generation is not limited to the peripheral auditory system. However, there are abnormalities seen in BERA in tinnitus patients depicting auditory pathway involvement. Oto-acoustic emissions are mechanical vibrations generated in the cochlea, which are evaluated by TEOAE and DPOAE whereas BERA evaluates both cochlea and brainstem auditory pathway for any conduction abnormalities. The aim of the study is to analyze the changes in OAE and BERA in patients suffering from tinnitus with normal hearing, which may help us to understand the patho-physiology of tinnitus.

METHODS

This is a prospective study conducted in a tertiary care hospital in Northern India between 1^st December 2015 to 31^st July 2017. All patients of tinnitus with normal hearing were included in the study group, whereas Individuals with normal hearing with no other ear complaints were included in control group. Total 160 Ears were evaluated with 80 ears in both study and control group each. Patients with PTA >25dB, age >55 years or any chronic medical illness were excluded from the study.

RESULTS

80 individuals (46 Males and 34 Females) were divided into study and control Group (80 Ears each). Tinnitus was bilateral in 28 subjects (53.84%) and unilateral in 24 subjects (46.16%). Both control and study group showed significant difference in TEOAE and DPOAE study. In TEOAE, 8 (10%) ears in control group and 30 ears (37.5%) in study group showed test result as REFER whereas in DPOAE 10 (12.5%) ears in control group and 35 (43.8%) ears showed test result as REFER. All these result were statistically significant. In BERA the latency of wave I was significantly prolonged in study group as compared to control group, while difference between all other parameters between the two groups was insignificant.

CONCLUSIONS

There were various significant abnormalities seen in parameters of Oto-Acoustic Emissions (OAE) and Brainstem Evoked Response Audiometry (BERA). So these tests should be included in the test battery for the screening of patients complaining of tinnitus even with normal hearing.

Stapedial reflex threshold predicts individual loudness tolerance for people with autistic spectrum disorders

People with autism spectrum disorder (ASD) frequently show the symptoms of oversensitivity to sound (hyperacusis). Although the previous studies have investigated methods for quantifying hyperacusis in ASD, appropriate physiological signs for quantifying hyperacusis in ASD remain poorly understood. Here, we investigated the relationship of loudness tolerance with the threshold of the stapedial reflex and with contralateral suppression of the distortion product otoacoustic emissions, which has been suggested to be related to hyperacusis in people without ASD. We tested an ASD group and a neurotypical group. The results revealed that only the stapedial reflex threshold was significantly correlated with loudness tolerance in both groups. In addition to reduced loudness tolerance, people with lower stapedial reflex thresholds also exhibited higher scores on the Social Responsiveness Scale-2.

Swept-Tone Stimulus-Frequency Otoacoustic Emissions in Human Newborns

Several types of otoacoustic emissions have been characterized in newborns to study the maturational status of the cochlea at birth and to develop effective tests of hearing. The stimulus-frequency otoacoustic emission (SFOAE), a reflection-type emission elicited with a single low-level pure tone, is the least studied of these emissions and has not been comprehensively characterized in human newborns. The SFOAE has been linked to cochlear tuning and is sensitive to disruptions in cochlear gain (i.e., hearing loss) in adult subjects. In this study, we characterize SFOAEs evoked with rapidly sweeping tones in human neonates and consider the implications of our findings for human cochlear maturation. SFOAEs were measured in 29 term newborns within 72 hr of birth using swept tones presented at 2 oct/s across a four-octave frequency range (0.5–8 kHz); 20 normal-hearing young adults served as a control group. The prevalence of SFOAEs in newborns was as high as 90% (depending on how response “presence” was defined). Evidence of probe-tip leakage and abnormal ear-canal energy reflectance was observed in those ears with absent or unmeasurable SFOAEs. Results in the group of newborns with present stimulus-frequency emissions indicate that neonatal swept-tone SFOAEs are adult-like in morphology but have slightly higher amplitude compared with adults and longer SFOAE group delays. The origin of these nonadult-like features is probably mixed, including contributions from both conductive (ear canal and middle ear) and cochlear immaturities.

Sensorineural Hearing Loss in Newborns Hospitalized in Neonatal Intensive Care Unit: An Observational Study

Children hospitalized in Neonatal Intensive Care Units (NICU) present an increased risk for Sensorineural Hearing Loss (SNHL) due to prematurity, hypoxia-ischemia, hyperventilation, low birth weight and the use of ototoxic drugs. The aim of this study was to assess the prevalence of SNHL in newborns hospitalized in a NICU using Transient Evoked Otoacoustic Emissions (TEOAE) and Automated Auditory Brainstem Responses (A-ABR) and analyze the associated risk factors. A sample of 153 newborns hospitalized in NICU underwent TEOAE, A-ABR and clinical ABR to evaluate the presence of hearing deficits. Prevalence of SNHL was calculated and odds ratio for specific risk factors was measured. One-hundred fifteen babies (86.7%) presented normal hearing at TEOAE and A-ABR. Fifteen children had a REFER response at TEOAE and a PASS response at A-ABR. Twenty-five children (16.3%) had a REFER A-ABR and were addressed to clinical ABR. A diagnosis of SNHL was made in 12 (7.8%) newborns. An increased risk of SNHL was observed in preterm children <28 weeks (p=0.0135), in children with neurological disorders (p=0.02), that underwent surgery (p=0.0002), affected from premature retinopathy (p=0.0006), craniofacial malformation (p=0.007) and that had sepsis (p=0.04). Additional risk factors for SNHL in our sample were a maternal disease during pregnancy (p=0.0011), cesarean delivery (p<0.0001) and a twin pregnancy (p<0.0001). SNHL in newborns is correlated with hospitalization in NICU. An accurate hearing screening associated to a rigorous clinical medical collection of data is necessary to promptly identify cases of SNHL in children with a special attention to those hospitalized in NICU and plan proper intervention.

Examining replicability of an otoacoustic measure of cochlear function during selective attention

Attention to a target stimulus within a complex scene often results in enhanced cortical representations of the target relative to the background. It remains unclear where along the auditory pathways attentional effects can first be measured. Anatomy suggests that attentional modulation could occur through corticofugal connections extending as far as the cochlea itself. Earlier attempts to investigate the effects of attention on human cochlear processing have revealed small and inconsistent effects. In this study, stimulus-frequency otoacoustic emissions were recorded from a total of 30 human participants as they performed tasks that required sustained selective attention to auditory or visual stimuli. In the first sample of 15 participants, emission magnitudes were significantly weaker when participants attended to the visual stimuli than when they attended to the auditory stimuli, by an average of 5.4 dB. However, no such effect was found in the second sample of 15 participants. When the data were pooled across samples, the average attentional effect was significant, but small (2.48 dB), with 12 of 30 listeners showing a significant effect, based on bootstrap analysis of the individual data. The results highlight the need for considering sources of individual differences and using large sample sizes in future investigations.

Mammalian behavior and physiology converge to confirm sharper cochlear tuning in humans

Frequency analysis of sound by the cochlea is the most fundamental property of the auditory system. Despite its importance, the resolution of this frequency analysis in humans remains controversial. The controversy persists because the methods used to estimate tuning in humans are indirect and have not all been independently validated in other species. Some data suggest that human cochlear tuning is considerably sharper than that of laboratory animals, while others suggest little or no difference between species. We show here in a single species (ferret) that behavioral estimates of tuning bandwidths obtained using perceptual masking methods, and objective estimates obtained using otoacoustic emissions, both also employed in humans, agree closely with direct physiological measurements from single auditory-nerve fibers. Combined with human behavioral data, this outcome indicates that the frequency analysis performed by the human cochlea is of significantly higher resolution than found in common laboratory animals. This finding raises important questions about the evolutionary origins of human cochlear tuning, its role in the emergence of speech communication, and the mechanisms underlying our ability to separate and process natural sounds in complex acoustic environments.

Noise-induced Cochlear Synaptopathy and Signal Processing Disorders

Noise-induced hidden hearing loss (NIHHL) has attracted great attention in hearing research and clinical audiology since the discovery of significant noise-induced synaptic damage in the absence of permanent threshold shifts (PTS) in animal models. Although the extant evidence for this damage is based on animal models, NIHHL likely occurs in humans as well. This review focuses on three issues concerning NIHHL that are somewhat controversial: (1) whether disrupted synapses can be re-established; (2) whether synaptic damage and repair are responsible for the initial temporal threshold shifts (TTS) and subsequent recovery; and (3) the relationship between the synaptic damage and repair processes and neural coding deficits. We conclude that, after a single, brief noise exposure, (1) the damaged and the totally destroyed synapses can be partially repaired, but the repaired synapses are functionally abnormal; (2) While deficits are observed in some aspects of neural responses related to temporal and intensity coding in the auditory nerve, we did not find strong evidence for hypothesized coding-in-noise deficits; (3) the sensitivity and the usefulness of the envelope following responses to amplitude modulation signals in detecting cochlear synaptopathy is questionable.

Cochlear Function in Adults with Epilepsy and Treated with Carbamazepine

Background: Epilepsy is a chronic medical disease and is associated with comorbid adverse somatic conditions due to epilepsy itself or its long-term treatment. Objectives: This study evaluated cochlear function in patients with idiopathic epilepsy and treated with carbamazepine (CBZ). Patients and Methods: Included were 47 patients (mean age = 34.56 ± 7.11 years and duration of illness = 17.84 ± 7.21 years) and 40 healthy subjects. They underwent pure-tone audiometry and transient evoked otoacoustic emission (TEOAE) analyses. Results: Hearing loss (mainly bilateral mild) was reported in one third of patients. Compared to controls, patients had lower TEOAE amplitudes at 1.0–4.0 kHz particularly at high frequencies (3 and 4 kHz). Significant correlations were identified between TEOAE amplitudes with CBZ dose (at 3 kHz: r = –0.554, p = 0.008; at 4 kHz: r = –0.347, p = 0.01), its serum level (at 4 kHz: r = –0.280, p = 0.045) and duration of treatment (at 3 kHz: r = –0.392, p = 0.008; at 4 kHz: r = –0.542, p = 0.001). Conclusions: Long-term CBZ treatment may result in cochlear dysfunction and auditory deficits.

Towards the preferred stimulus parameters for distortion product otoacoustic emissions in adults: A preliminary study

BACKGROUND

 Although distortion product otoacoustic emissions (DPOAEs) are useful in evaluating cochlear outer hair cell function, determining the optimal stimulus parameters could result in a more reliable, sensitive and specific diagnostic tool across the range of DPOAE applications. Objectives: To identify which stimulus parameters warrant further investigation for eliciting the largest and most reliable DPOAEs in adult humans. Method: A single group, repeated measures design involving a convenience sample of 20 normal-hearing participants between 19 and 24 years of age. Results: Descriptive statistics and mixed model analyses suggested L1/L2 intensity levels of 65/65 dB sound pressure level (SPL) and 65/55 dB SPL, and f2/f1 ratios of 1.18, 1.20 and 1.22 elicited larger and more reliable DPOAEs in both ears. Conclusion: Further investigation of the 65/65 dB SPL and 65/55 dB SPL intensity levels and the 1.18, 1.20 and 1.22 f2/f1 ratios is warranted to determine the stimulus parameters for eliciting the largest and most reliable DPOAEs in adult humans across the range of DPOAE applications.

Analyzing transient-evoked otoacoustic emissions by concentration of frequency and time

The linear part of transient evoked otoacoustic emission (TEOAE) is thought to be generated via coherent reflection near the characteristic place of constituent wave components. Because of the tonotopic organization of the cochlea, high frequency emissions return earlier than low frequencies; however, due to the random nature of coherent reflection, the instantaneous frequency (IF) and amplitude envelope of TEOAEs both fluctuate. Multiple reflection components and synchronized spontaneous emissions can further make it difficult to extract the IF by linear transforms. This paper proposes to model TEOAEs as a sum of intrinsic mode-type functions and analyze it by a nonlinear-type time-frequency (T-F) analysis technique called concentration of frequency and time (ConceFT). When tested with synthetic otoacoustic emission signals with possibly multiple oscillatory components, the present method is able to produce clearly visualized traces of individual components on the T-F plane. Further, when the signal is noisy, the proposed method is compared with existing linear and bilinear methods in its accuracy for estimating the fluctuating IF. Results suggest that ConceFT outperforms the best of these methods in terms of optimal transport distance, reducing the error by 10% to 21% when the signal to noise ratio is 10 dB or below.

Auditory function and motor proficiency in type 1 diabetic children: A case-control study

OBJECTIVES

The aim of the study was to evaluate the auditory and motor functions in children with insulin dependent diabetes mellitus (IDDM).

METHODS

This case-control study, 65 diabetic children, receiving care in Diabetes Center of 17 Sharivar Hospital, were enrolled. 130 controls were matched to cases by age and sex. The authors performed audio-vestibular tests, including pure tone audiometry (PTA), distortion product otoacoustic emission (DPOAE), auditory brainstem response (ABR), bedside head-impulse test and dynamic visual acuity test. Motor function was evaluated using of Bruininks-Oseretsky Test of Motor Proficiency, Second Edition (BOT-2).

RESULTS

The results showed higher thresholds of air conduction PTA and a prolonged peak latency of wave V (ABR) in diabetic children as compared to controls (all Ps < 0.001). The odds of normal response in DPOAE of cases decreased by 0.44-0.82 - fold. Although clinical vestibular outcomes were worse in cases, differences were not significant. In BOT-2, the cases had statistically significant lower scores (standard score = -0.58, P < 0.05) than the controls for the Total Motor Composite. Also diabetic girls had more skill motor impairment compared to boys with IDDM.

CONCLUSION

Based on our study, metabolic disturbances present in Type I diabetes cause disturbances in different parts of auditory and balance functions.