The Association between Prenatal Nicotine Exposure and Offspring's Hearing Impairment

OBJECTIVES

 The objective of this study is to evaluate whether there is an association between in-utero exposure to nicotine and subsequent hearing dysfunction.

MATERIALS AND METHODS

 Secondary analysis of a multicenter randomized trial to prevent congenital cytomegalovirus (CMV) infection among gravidas with primary CMV infection was conducted. Monthly intravenous immunoglobulin hyperimmune globulin therapy did not influence the rate of congenital CMV. Dyads with missing urine, fetal or neonatal demise, infants diagnosed with a major congenital anomaly, congenital CMV infection, or with evidence of middle ear dysfunction were excluded. The primary outcome was neonatal hearing impairment in one or more ears defined as abnormal distortion product otoacoustic emissions (DPOAEs; 1 to 8 kHz) that were measured within 42 days of birth. DPOAEs were interpreted using optimized frequency-specific level criteria. Cotinine was measured via enzyme-linked immunosorbent assay kits in maternal urine collected at enrollment and in the third trimester (mean gestational age 16.0 and 36.7 weeks, respectively). Blinded personnel ran samples in duplicates. Maternal urine cotinine >5 ng/mL at either time point was defined as in-utero exposure to nicotine. Multivariable logistic regression included variables associated with the primary outcome and with the exposure (p < 0.05) in univariate analysis.

RESULTS

 Of 399 enrolled patients in the original trial, 150 were included in this analysis, of whom 46 (31%) were exposed to nicotine. The primary outcome occurred in 18 (12%) newborns and was higher in nicotine-exposed infants compared with those nonexposed (15.2 vs. 10.6%, odds ratio [OR] 1.52, 95% confidence interval [CI] 0.55-4.20), but the difference was not significantly different (adjusted odds ratio [aOR] = 1.0, 95% CI 0.30-3.31). This association was similar when exposure was stratified as heavy (>100 ng/mL, aOR 0.72, 95% CI 0.15-3.51) or mild (5-100 ng/mL, aOR 1.28, 95% CI 0.33-4.95). There was no association between nicotine exposure and frequency-specific DPOAE amplitude.

CONCLUSION

 In a cohort of parturients with primary CMV infection, nicotine exposure was not associated with offspring hearing dysfunction assessed with DPOAEs.

KEY POINTS

· Nicotine exposure was quantified from maternal urine.. · Nicotine exposure was identified in 30% of the cohort.. · Exposure was not associated with offspring hearing dysfunction..

Pathophysiology of Postoperative Hearing Disorders after Vestibular Schwannoma Resection: Insights from Auditory Brainstem Response and Otoacoustic Emissions

Background: In order to better understand the pathophysiology of surgically induced hearing loss after vestibular schwannoma (VS) surgery, we postoperatively analyzed the hearing status in a series of patients where hearing was at least partially preserved. Methods: Hearing was assessed through tonal audiometry, speech discrimination score, maximum word recognition score (dissyllabic word lists-MaxIS), otoacoustic emissions (OAEs), and auditory brainstem response (ABR). The magnetic resonance imaging (MRI) tumor characterization was also noted. Results: In a series of 24 patients operated on for VS over 5 years, depending on the results of this triple hearing exploration, we could identify, after surgery, patients with either a myelin alteration or partial damage to the acoustic fibers, others with a likely partial cochlear ischemia, and some with partial cochlear nerve ischemia. One case with persisting OAEs and no preoperative ABR recovered hearing and ABR after surgery. Long follow-up (73 ± 57 months) revealed a mean hearing loss of 30 ± 20 dB with a drastic drop of MaxIS. MRI revealed only 25% of fundus invasion. Conclusion: a precise analysis of hearing function, not only with classic audiometry but also with ABR and OEAs, allows for a better understanding of hearing damage in VS surgery.

ABO blood group and cochlear function: evidence from a large sample size study

OBJECTIVE

The present study investigated the effect of blood group on cochlear function in a large participant sample across different age groups. The study hypothesis was that participants with blood group O would show relatively reduced cochlear function as reflected in otoacoustic emission (OAE) measures.

DESIGN

Data were collected from transient evoked otoacoustic emission (TEOAE), distortion product otoacoustic emission (DPOAE), DPOAE input/output (I/O) function, and spontaneous otoacoustic emission (SOAE) recordings.

STUDY SAMPLE

Four hundred and sixty-three normal hearing adults aged 20-59 years among the four ABO blood groups participated in the study.

RESULTS

TEOAE and DPOAE amplitudes did not reveal significant differences for participants with blood group O compared with participants with non-O blood groups. No significant differences in I/O function categories were found among participants with different blood groups. SOAE prevalence was also not significantly different across blood groups. However, previously reported age and gender differences for OAE variables were confirmed.

CONCLUSIONS

Participants with blood group O were not found to have significantly reduced cochlear function, based on OAE measures. Results from the current study do not support the hypothesis that normal hearing individuals with different ABO blood groups differ in level of cochlear function.

Inner Ear Function Evaluation in Mobile Phone Users: A Cross-Sectional Study From a Tertiary Care Centre in North India

Background India has approximately 1.02 billion mobile phone users. The electromagnetic radiations emitted by telecommunication systems are absorbed by the recipient's body, leading to changes in brain electrical activity, sensations of warmth or burning around the ear, and alterations in the blood-brain barrier. The inner ear, being the closest organ during mobile phone use, directly receives these electromagnetic radiations. This study aims to assess the inner ear function among mobile phone users, investigate the impact of mobile phones on the hearing thresholds of volunteers through pure-tone audiometry (PTA), and delve into the same using otoacoustic emissions (OAE). Methodology A cross-sectional study was conducted at a single center in North India from September 2020 to March 2021. The sample size of around 100 was determined using G Power software (G Power, Aichach, Germany), including volunteers aged 18-25, using mobile phones for over a year with normal hearing. Exclusions involved various ear-related histories or chronic systemic illnesses. Dominant and non-dominant ear groups were formed based on mobile phone usage. The study involved comprehensive ENT examinations, pure-tone audiometry, and otoacoustic emissions. We performed statistical analyses using SPSS version 22.0 (IBM Corp., Armonk, NY), which presented descriptive statistics and employed tests for group comparisons. Results Most participants were in the 21-23 age group (56%), with a mean age of 22.16 ± 1.77 years. There were 45 males and 55 females. The mean mobile phone usage was 6.6 ± 1.98 years, with varying daily durations. The dominant ear for mobile phone usage was predominantly the right ear (75 participants). Pure-tone audiometry results showed no statistically significant differences between dominant and non-dominant ears. Among the 24 participants with absent OAE, no significant association was found with mobile phone usage duration. Notably, the highest incidence of absent OAE occurred in the 120-180-minute usage category. Conclusion Mobile phones have seamlessly integrated into the lives of individuals, witnessing an exponential increase in users over time. The inner ear, situated in proximity to mobile phone usage, is of particular concern. While there is existing evidence indicating potential adverse effects of mobile phones on the inner ear, further long-term studies involving larger populations are essential to comprehensively evaluating the impact on inner ear function among mobile phone users.

Parametric information about eye movements is sent to the ears

Eye movements alter the relationship between the visual and auditory spatial scenes. Signals related to eye movements affect neural pathways from the ear through auditory cortex and beyond, but how these signals contribute to computing the locations of sounds with respect to the visual scene is poorly understood. Here, we evaluated the information contained in eye movement-related eardrum oscillations (EMREOs), pressure changes recorded in the ear canal that occur in conjunction with simultaneous eye movements. We show that EMREOs contain parametric information about horizontal and vertical eye displacement as well as initial/final eye position with respect to the head. The parametric information in the horizontal and vertical directions can be modeled as combining linearly, allowing accurate prediction of the EMREOs associated with oblique (diagonal) eye movements. Target location can also be inferred from the EMREO signals recorded during eye movements to those targets. We hypothesize that the (currently unknown) mechanism underlying EMREOs could impose a two-dimensional eye-movement-related transfer function on any incoming sound, permitting subsequent processing stages to compute the positions of sounds in relation to the visual scene.

Leisure noise exposure and hearing outcomes among Canadians aged 6 to 79 years

OBJECTIVE

To examine the association between individual and cumulative leisure noise exposure in addition to acceptable yearly exposure (AYE) and hearing outcomes among a nationally representative sample of Canadians.

DESIGN

Audiometry, distortion-product otoacoustic emissions (DPOAEs) and in-person questionnaires were used to evaluate hearing and leisure noise exposure across age, sex, and household income/education level. High-risk cumulative leisure noise exposure was defined as 85 dBA or greater for 40 h or more per week, with AYE calculations also based on this occupational limit.

STUDY SAMPLE

A randomised sample of 10,460 respondents, aged 6-79, completed questionnaires and hearing evaluations between 2012 and 2015.

RESULTS

Among 50-79 year olds, high-risk cumulative leisure noise was associated with increased odds of a notch while high exposure to farming/construction equipment noise was associated with hearing loss, notches and absent DPOAEs. No associations with hearing loss were found however, non-significant tendencies observed included higher mean hearing thresholds, notches and hearing loss odds.

CONCLUSION

Educational outreach and monitoring of hearing among young and middle-aged populations exposed to hazardous leisure noise would be beneficial.

Characterizing a Joint Reflection-Distortion OAE Profile in Humans With Endolymphatic Hydrops

OBJECTIVES

Endolymphatic hydrops (EH), a hallmark of Meniere disease, is an inner-ear disorder where the membranes bounding the scala media are distended outward due to an abnormally increased volume of endolymph. In this study, we characterize the joint-otoacoustic emission (OAE) profile, a results profile including both distortion- and reflection-class emissions from the same ear, in individuals with EH and speculate on its potential utility in clinical assessment and monitoring.

DESIGN

Subjects were 16 adults with diagnosed EH and 18 adults with normal hearing (N) matched for age. Both the cubic distortion product (DP) OAE, a distortion-type emission, and the stimulus-frequency (SF) OAE, a reflection-type emission, were measured and analyzed as a joint OAE profile. OAE level, level growth (input/output functions), and phase-gradient delays were measured at frequencies corresponding to the apical half of the human cochlea and compared between groups.

RESULTS

Normal hearers and individuals with EH shared some common OAE patterns, such as the reflection emissions being generally higher in level than distortion emissions and showing more linear growth than the more strongly compressed distortion emissions. However, significant differences were noted between the EH and N groups as well. OAE source strength (a metric based on OAE amplitude re: stimulus level) was significantly reduced, as was OAE level, at low frequencies in the EH group. These reductions were more marked for distortion than reflection emissions. Furthermore, two significant changes in the configuration of OAE input/output functions were observed in ears with EH: a steepened growth slope for reflection emissions and an elevated compression knee for distortion emissions. SFOAE phase-gradient delays at 40 dB forward-pressure level were slightly shorter in the group with EH compared with the normal group.

CONCLUSIONS

The underlying pathology associated with EH impacts the generation of both emission types, reflection and distortion, as shown by significant group differences in OAE level, growth, and delay. However, hydrops impacts reflection and distortion emissions differently. Most notably, DPOAEs were more reduced by EH than were SFOAEs, suggesting that pathologies associated with the hydropic state do not act identically on the generation of nonlinear distortion at the hair bundle and intracochlear reflection emissions near the peak of the traveling wave. This differential effect underscores the value of applying a joint OAE approach to access both intracochlear generation processes concurrently.

Conserved features of eye movement related eardrum oscillations (EMREOs) across humans and monkeys

Auditory and visual information involve different coordinate systems, with auditory spatial cues anchored to the head and visual spatial cues anchored to the eyes. Information about eye movements is therefore critical for reconciling visual and auditory spatial signals. The recent discovery of eye movement-related eardrum oscillations (EMREOs) suggests that this process could begin as early as the auditory periphery. How this reconciliation might happen remains poorly understood. Because humans and monkeys both have mobile eyes and therefore both must perform this shift of reference frames, comparison of the EMREO across species can provide insights to shared and therefore important parameters of the signal. Here we show that rhesus monkeys, like humans, have a consistent, significant EMREO signal that carries parametric information about eye displacement as well as onset times of eye movements. The dependence of the EMREO on the horizontal displacement of the eye is its most consistent feature, and is shared across behavioural tasks, subjects and species. Differences chiefly involve the waveform frequency (higher in monkeys than in humans) and patterns of individual variation (more prominent in monkeys than in humans), and the waveform of the EMREO when factors due to horizontal and vertical eye displacements were controlled for. This article is part of the theme issue 'Decision and control processes in multisensory perception'.

Cochlear Function in Individuals with and without Spontaneous Otoacoustic Emissions

PURPOSE

This study investigated the status of spontaneous otoacoustic emissions (SOAEs) on cochlear function in a cohort of male/female participants with a wide age range. It examined whether there was a correlation between the presence of SOAEs and measurements of transient evoked otoacoustic emissions (TEOAEs), distortion product otoacoustic emissions (DPOAEs), SOAEs and extended high-frequency (EHF) hearing thresholds.

METHODS

463 participants (222 male, 241 female; age range 20-59 years) with pure-tone thresholds ≤25 dB HL for octave frequencies of 500-8000 Hz were included in the study, divided into three age groups (20-29, 30-39, and 40-59 years). Evaluations included EHF (9000-16,000 Hz) hearing thresholds and TEOAE, DPOAE and SOAE measures.

RESULTS

Multiple regression models showed that participants with SOAEs had larger expected amplitudes and signal-to-noise ratios (SNRs) for TEOAE and DPOAE responses than participants without SOAEs, holding gender and age variables constant. Spearman correlation tests identified deterioration in TEOAE and DPOAE amplitudes and SNRs, and EHF hearing thresholds with age in participants without SOAEs. Among participants with SOAEs, no significant decreases in TEOAE and DPOAE measures were shown in participants with older age. Nonetheless, as expected, EHF hearing thresholds did become worse with age, with or without SOAEs.

CONCLUSIONS

Participants with identifiable SOAEs had greater TEOAE and DPOAE amplitudes and SNRs than participants without SOAEs. SOAEs appear to be a useful marker of cochlear health in adults.

Neonatal Hearing Rescreening in a Second-Level Hospital: Problems and Solutions

Second-level hospitals face peculiarities that make it difficult to implement hearing rescreening protocols, which is also common in other settings. This study analyzes the hearing rescreening process in these kinds of hospitals. A total of 1130 individuals were included; in this cohort, 61.07% were hospital newborns who failed their first otoacoustic emission test after birth (n = 679) or were unable to perform the test (n = 11), and who were then referred to an outpatient clinic. The remaining 38.93% were individuals born in another hospital with their first test conducted in the outpatient clinic (n = 440). A high number of rescreenings were made outside of the recommended time frame, mainly in children referred from another hospital. There was a high lost-to-follow-up rate, especially regarding otolaryngologist referrals. Neonatal hearing screening at second-level hospitals is difficult because of staffing and time constraints. This results in turnaround times that are longer than recommended, interfering with the timely detection of hearing loss. This is particularly serious in outpatient children with impaired screening. Referral to out-of-town centers leads to unacceptable follow-up loss. Legislative support for all these rescreening issues is necessary. In this article, these findings are discussed and some solutions are proposed.

Epidemiological Profile of Neonates in Hearing Screening at a Maternity of a Tertiary Hospital in the state of Santa Catarina, Brazil

Introduction  The newborn hearing screening (NHS) test aims the early diagnostic of hearing deficits that may also harm the full development of communication and learning of the affected child. Objective  Trace the clinical and epidemiological profile of children born between July 2016 and July 2019; in addition to the outcome of the NHSs and factors related to failure in the hearing tests at a maternity of a tertiary hospital in Santa Catarina, Brazil. Methods  The present is a cross-sectional study. A census of those born in the period defined for study was performed and a script was developed for the review of medical records, based on the literature. Results  The sample can be considered homogeneous in relation to gender and age. The pregnant women had an average of 30.9 years. There were 30 neonates (1.9%) that did not undergo NHS. New evaluations were required in 288 patients (18.2%). Finally, 24 (1.5% of the population) remained with insufficient results in the retest. The following variables achieved statistical relevance with higher failure rates in tests and/or retests: natural delivery ( p  = 0.007), arterial hypertension present ( p  = 0.002), use of hydralazine ( p  = 0.038), and use of dipyrone in the test ( p  = 0.041) and retest ( p  = 0.003). Younger mothers had higher levels of normality in the test ( p  = 0.003) and retest ( p  = 0.161). The correlations between the other variables and the outcomes were not statistically significant. Conclusion  False positives (62.8%) in the first test showed a value higher than the ideal goal; those who did not undergo the NHS (1.9%) and who needed evaluation by a specialist, due to failure in the retest (1.5%), are within the quality goals defined by the Joint Committee on Infant Hearing (JCIH) in 2007.

Assessment of Hearing Impairment in Sick Newborns: A Prospective Observational Study

BACKGROUND

 Undiagnosed neonatal hearing loss causes severe language, cognitive, and behavioral problems in children. Sick newborns who spend 48 hours in the neonatal intensive care unit (NICU) have a 10- to 20-fold increased risk of permanent hearing loss. The aim of this study is to identify hearing impairment in high-risk sick newborns who spend at least 48 hours in the NICU.

METHODS

 The present prospective observational study was conducted at a single center. All sick neonates admitted to the NICU for a minimum of 48 hours at the JK Lon Hospital, Zanana Hospital, and Mahila Chikitsalaya, Sawai Man Singh (SMS) Medical College, Jaipur, Rajasthan, India, from June 2017 to May 2018 were considered eligible for the study. The primary outcome was the assessment of hearing loss of high-risk newborns using otoacoustic emissions at the time of discharge, six weeks of age, and automated auditory brainstem response (AABR) at three months of chronological age. The secondary outcome was to analyze the association of hearing loss with different risk factors in high-risk neonates.

RESULTS

 A total of 150 infants who had one or more risk factors were studied, 60 were female and 90 were male. No statistically significant difference in hearing loss was observed based on birth weight, sex, and gestational age. The first distortion-product otoacoustic emission (DPOAE) screening was done on infants at the time of discharge from the NICU. Eighty-three infants (55.33%) had "refer" on the first DPOAE and the remaining 67 (44.67%) were passed results at the time of discharge. At six weeks of life, on repeat screening with a second DPOAE test, 36% "refer" on the first screen had a "refer" result on the second DPOAE. However, 4.4% "pass" on the first screen turned out to be "refer" on the second screen. These 33 infants who had "refer" results on the second screen were subjected to testing. At 10 weeks of life, AABR was performed on 33 infants. Eleven infants out of 33 had sensorineural hearing loss (SNHL) on AABR. Hearing impairment with the DPOAE test was observed with risk factors neonatal hyperbilirubinemia (NHH), hypoxic ischemic encephalopathy (HIE), and very low birth weight (VLBW) and was statistically significant among all risk factors. But, no such association (between hearing impairment and risk factors) was observed with the AABR test. In our study, we found that the duration of mechanical ventilation in mean days 7.67±6.24 had statistically significant SNHL compared to the lesser duration of mechanical ventilation (p<0.001).

CONCLUSION

Two-stage DPOAE done prior to AABR is helpful in the early detection of hearing loss.

Protective and Therapeutic Effect of Platelet-Rich Plasma on Experimental Cisplatin Ototoxicity

Objective

Cisplatin is a chemotherapeutic agent with an ototoxic effect that is frequently used in head and neck cancers. There are studies in the literature conducted with various antioxidant substances to protect and/or prevent ototoxicity. This study aims to investigate whether platelet-rich plasma (PRP) has a protective and therapeutic effect on cisplatin ototoxicity.

Methods

A total of 40 Sprague Dawley albino rats were divided into six groups as control group (n=6), PRP-only group (n=6), cisplatin group (n=6), cisplatin + PRP group (n=6), PRP + cisplatin group (n=6), and donor group (n=10). At the beginning of the study and the 8th day, they were tested with distortion product otoacoustic emission (DPOAE). Assessment of DPOAE results was based on the signal-to-noise ratio in 2000, 3000, 4000, 6000, and 8000 Hz frequency bands. On the 8th day, the rats were sacrificed. For histological examinations, the temporal bones were dissected and fixed. After hematoxylin and eosin staining, the tissues were evaluated by light microscopy.

Results

In the DPOAE tests performed on the 0th and 8th days of the cisplatin group, it was observed that cisplatin caused hearing loss in the rat ears. It was determined that the cisplatin group at 2000 Hz, 3000 Hz and 4000 Hz had a significant decrease in hearing compared to all groups (p<0.015), while the cisplatin group at 6000 and 8000 Hz was characterized by hearing loss at a higher rate than all groups (p<0.001). At the end of the study, negative effects of cisplatin on both cellular dimensions (cytoplasmic vacuolization, cell degeneration, dilatation, apoptotic cells, nerve degeneration) and hearing function were observed. No protective or therapeutic effect of PRP on cisplatin ototoxicity was observed.

Conclusion

Our study showed that platelet-rich plasma did not have a significant effect in the treatment of hearing loss due to cisplatin ototoxicity and in preventing hearing loss in rats.

Hearing Loss in Bacterial Meningitis Revisited-Evolution and Recovery

Background

Hearing loss and deafness are well-known sequelae from bacterial meningitis (ABM) and may result in social dysfunction and learning difficulties. Yet, the timely development of hearing loss and restitution is poorly studied, especially among adults. Hearing loss was revisited using otoacoustic emissions (OAEs) to determine the occurrence, magnitude, and development of hearing loss among adults with ABM.

Methods

Distortion product OAEs were measured in patients with ABM the day of admission and days 2, 3, 5-7, and 10-14 and at follow-up 30-60 days after discharge. Frequencies were categorized as low (1, 1.5, 2 kHz), mid (3, 4, 5 kHz), mid-high (6, 7, 8 kHz), and high (9, 10 kHz). Audiometry was performed on discharge and 60 days after. Results were compared with 158 healthy controls.

Results

OAE was obtained in 32 patients. ABM was due to S. pneumoniae in 12 patients (38%). All patients were treated with dexamethasone. OAE emission threshold levels (ETLs) were significantly decreased upon admission and at follow-up in all frequencies compared with healthy controls. A substantial and significant decrease in ETLs was found in S. pneumoniae meningitis. Sensorineural hearing loss (SNHL) >20 dB was present in 13 of 23 (57%) at discharge and in 11 of 18 patients (61%) 60 days after discharge. Hearing recovery decreased from day 3.

Conclusions

Hearing loss in ABM still affects >60% of patients despite treatment with dexamethasone. In S. pneumoniae meningitis, SNHL is profound and permanent. A window of opportunity for systemic or local treatments aiming to preserve cochlear function is proposed.

[Clinical protocol: audiological assessment of infants in Russian Federation. Part I]

The clinical protocol of audiological assessment in infants was prepared by the workgroup of Russian pediatric audiologists from different regions. The goal of the protocol is unification approaches to audiological diagnosis of the infants. The protocol has been developed according the evidence based medicine principles, by reviewing current scientific publications on the topic and taking into account the order of providing medical services and other clinical practice guidelines. When direct evidence was not available, both indirect evidence and consensus practice were considered in making recommendations. This guideline is not intended to serve as a standard to dictate precisely how the child should be diagnosed. This guideline is meant to provide the evidence base from which the clinician can make individualized decisions for each patient. The first part of the protocol covers following sections: equipment, staff requirements, timing of the diagnostics, case history and risk factors, preparing the child for the appointment, sedation and general anesthesia, otoscopy, tympanometry and acoustic reflex, otoacoustic emissions, skin preparing, electrode montage, choosing the stimulators, auditory brainstem responses on broadband and narrow-band stimuli, on bone conducted stimuli, auditory steady-state responses, masking, combined correction factors.

Contralateral suppression of transient evoked otoacoustic emissions in adults: A normative study

BACKGROUND

 Whilst otoacoustic emission (OAE) testing has proved to be valuable in revealing information about cochlear outer hair cell integrity, it does not provide insight into the afferent and efferent pathways once the stimulus has reached neural receptors. This information can be obtained objectively through contralateral acoustic stimulation (CAS) suppression. However, obtaining normative data is essential in the implementation of such tests.

OBJECTIVES

 The primary aim was to undertake a small pilot study to collect the CAS suppression across a predefined frequency range in order to provide a preliminary normative data set to be used with the newly developed transient evoked otoacoustic emission (TEOAE)-CAS module (PATH MEDICAL, Germering, Germany). Secondary aims included the analysis of the relationships between left and right CAS suppression, between male and female CAS suppression and between TEOAE signal-to-noise ratio (SNR) and CAS suppression.

METHODS

 The purpose of this study was to determine preliminary normative data for contralateral TEOAE suppression from 40 normal ears of 20 healthy young adults (10 males and 10 females). Subjects were recruited using purposive sampling. The CAS suppression responses were obtained automatically by means of the data-collection protocol on the device used. From the data obtained, correlations between TEOAE SNR and CAS suppression were made using Pearson's correlation coefficient.

RESULTS

 The data were statistically processed to form a normative database which possesses the potential of serving as a basis for further research aimed at determining the utility of CAS suppression testing when evaluating ear pathology. A mean CAS suppression of 0.8 decibels (dB) (0.61 SD) was obtained. There was no statistically significant relationship between TEOAE SNR and CAS suppression. There was no significant suppression difference in terms of laterality of ears or gender.

CONCLUSION

 Normative values for CAS suppression of TEOAEs in a group of normal-hearing individuals were obtained using the newly developed TEOAE-CAS module (PATH MEDICAL, Germering, Germany). The availability of normative data for contralateral TEOAE suppression using the studied module allows for it to become commercially available, which will enable researchers and audiologists to perform this measurement in different populations in the evaluation of ear pathology.

Analysis of Newborn Hearing Screening Results in South Korea after National Health Insurance Coverage: A Nationwide Population-Based Study

Newborn hearing screening (NHS) has been covered by national health insurance since October 2018 in Korea. However, the results of the NHS are not reported due to the absence of a follow-up tracking system. This study analyzed the status and the predicted referral rates of NHS after the Korean national health insurance coverage by analyzing the National Health Insurance Service database in 2019 and 2020. The NHS coverage was 91.7% of total birth in 2019 and 92.1% in 2020. The predicted referral rate of NHS calculated by the duplicated NHS cases was 1.05% in 2019 and 0.99% in 2020. However, another predicted referral rate calculated by the number of diagnostic auditory brainstem responses (ABRs) performed was 1.44% in 2019 and 1.43% in 2020. The first NHS was performed within one day of birth for 96.5% of the babies and within three days of birth for 97%. However, diagnostic ABR was adequately performed within three months of birth for only 4.3%, while 82.3% performed the test after six months which delays appropriate intervention for hearing loss. National support such as national coordinators, follow-up tracking, and data management systems are needed for early hearing detection and intervention of newborns and infants in Korea.

Congenital Nonprofound Bilateral Sensorineural Hearing Loss in Children: Comprehensive Characterization of Auditory Function and Hearing Aid Benefit

A prospective cross-sectional design was used to characterize congenital bilateral sensorineural hearing loss (SNHL). The underlying material of >30,000 consecutively screened newborns comprised 11 subjects with nonprofound, alleged nonsyndromic, SNHL. Comprehensive audiological testing was performed at ≈11 years of age. Results showed symmetrical sigmoid-like median pure-tone thresholds (PTTs) reaching 50−60 dB HL. The congenital SNHL revealed recruitment, increased upward spread of masking, distortion product otoacoustic emission (DPOAE) dependent on PTT (≤60 dB HL), reduced auditory brainstem response (ABR) amplitude, and normal magnetic resonance imaging. Unaided recognition of speech in spatially separate competing speech (SCS) deteriorated with increasing uncomfortable loudness level (UCL), plausibly linked to reduced afferent signals. Most subjects demonstrated hearing aid (HA) benefit in a demanding laboratory listening situation. Questionnaires revealed HA benefit in real-world listening situations. This functional characterization should be important for the outline of clinical guidelines. The distinct relationship between DPOAE and PTT, up to the theoretical limit of cochlear amplification, and the low ABR amplitude remain to be elucidated. The significant relation between UCL and SCS has implications for HA-fitting. The fitting of HAs based on causes, mechanisms, and functional characterization of the SNHL may be an individualized intervention approach and deserves future research.

Noise exposure and hearing status among employees using communication headsets

OBJECTIVES

The objective of this study was to assess the hearing of employees using communication headsets with regard to their exposure to noise.

MATERIAL AND METHODS

The study group comprised 213 employees, including 21 workers of the furniture industry, 15 court transcribers and 177 call center operators, aged 19-55 years, working with headsets for a period of up to 25 years. All the participants underwent a standard puretone audiometry, extended high-frequency audiometry (EHFA) as well as transient-evoked otoacoustic emissions (TEOAEs) and distortion-product otoacoustic emissions (DPOAEs). Noise exposure from headsets was evaluated using the microphone in a real ear technique according to PN-EN ISO 11904-1:2008.

RESULTS

Personal daily noise exposure levels ranged 57-96 dB and exceeded 85 dB only in 1.4% of the call center operators. Forty-two percent of the participants had bilateral normal hearing in the standard frequency range of 250-8000 Hz, and 33% in the extended highfrequency range of 9-16 kHz. It was found that DPOAEs were present bilaterally in 59% of the participants. Reproducibility of TEOAE at >70% and signal-to-noise ratio at >6 was exhibited by 42% and 17% of them, respectively. The 3 subgroups of workers differed in age, gender, noise exposure and type of headsets in use. However, after adjusting for age and gender, significant differences between these subgroups in terms of hearing were mostly visible in EHFA. A significant impact of age, gender, daily noise exposure level and current job tenure on hearing tests results was also noted among the call center operators and the transcribers. The most pronounced were the effects of age and gender, whereas the impact of the daily noise exposure level was less evident.

CONCLUSIONS

It seems that EHFA is useful for recognizing early signs of noise-induced hearing loss among communication headset users. However, further studies are needed before any firm conclusions concerning the risk of hearing impairment due to the use of such devices can be drawn. Int J Occup Med Environ Health. 2022;35(5):585-614.

Characterizing the Relationship Between Reflection and Distortion Otoacoustic Emissions in Normal-Hearing Adults

Otoacoustic emissions (OAEs) arise from one (or a combination) of two basic generation mechanisms in the cochlea: nonlinear distortion and linear reflection. As a result of having distinct generation processes, these two classes of emissions may provide non-redundant information about hair-cell integrity and show distinct sensitivities to cochlear pathology. Here, we characterize the relationship between reflection and distortion emissions in normal hearers across a broad frequency and stimulus-level space using novel analysis techniques. Furthermore, we illustrate the promise of this approach in a small group of individuals with mild-moderate hearing loss. A "joint-OAE profile" was created by measuring interleaved swept-tone stimulus-frequency OAEs (SFOAEs) and 2f1-f2 distortion-product OAEs (DPOAEs) in the same ears using well-considered parameters. OAE spectra and input/output functions were calculated across five octaves. Using our specific recording protocol and analysis scheme, SFOAEs in normal hearers had higher levels than did DPOAEs, with the most pronounced differences occurring at the highest stimulus levels. Also, SFOAE compression occurred at higher stimulus levels (than did DPOAE compression) and its growth in the compressed region was steeper. The diagnostic implications of these findings and the influence of the measurement protocol on both OAEs (and on their relationship) are discussed.

MicroRNA expression is associated with auditory dysfunction in workers exposed to ototoxic solvents and noise

This study is part of a project on early hearing dysfunction induced by combined exposure to volatile organic compounds (VOCs) and noise in occupational settings. In a previous study, 56 microRNAs were found differentially expressed in exposed workers compared to controls. Here, we analyze the statistical association of microRNA expression with audiometric hearing level (HL) and distortion product otoacoustic emission (DPOAE) level in that subset of differentially expressed microRNAs. The highest negative correlations were found; for HL, with miR-195-5p and miR-122-5p, and, for DPOAEs, with miR-92b-5p and miR-206. The homozygous (mut) and heterozygous (het) variants of the gene hOGG1 were found disadvantaged with respect to the wild-type (wt), as regards the risk of hearing impairment due to exposure to VOCs. An unsupervised artificial neural network (auto contractive map) was also used to detect and show, using graph analysis, the hidden connections between the explored variables. These findings may contribute to the formulation of mechanistic hypotheses about hearing damage due to co-exposure to noise and ototoxic solvents.

Audiological Risk Factors, Referral Rates and Dropouts: 9 Years of Universal Newborn Hearing Screening in North Sardinia

Background: Objectives of the present work were to analyze the prevalence of hearing loss in our population of screened newborns during the first 9 years of the universal newborn hearing screening (UNHS) program at University Hospital Sassari (Italy) (AOU Sassari), to analyze the risk factors involved, and to analyze our effectiveness in terms of referral rates and dropout rates. Methods: Monocentric retrospective study whose target population included all the newborns born or referred to our hospital between 2011 and 2019. Results: From 2011 to 2019, a total of 11,688 babies were enrolled in our screening program. In total, 3.9‱ of wellborn babies and 3.58% of neonatal intensive care unit (NICU) babies had some degree of hearing loss. The most frequently observed risk factors among non-NICU babies were family history of hearing loss (3.34%) and craniofacial anomalies (0.16%), among NICU babies were low birth weight (54.91%) and prematurity (24.33%). In the multivariate analysis, family history of hearing loss (p < 0.001), NICU (p < 0.001), craniofacial anomalies (p < 0.001), low birth weight (<1500 g) (p = 0.04) and HIV (p = 0.03) were confirmed as risk factors. Conclusions: Our data are largely consistent with the literature and most results were expected, one relevant exception being the possible role of NICU as a confounding factor and the limited number of risk factors confirmed in the multivariate analysis.

Translational Applications of Machine Learning in Auditory Electrophysiology

Machine learning (ML) is transforming nearly every aspect of modern life including medicine and its subfields, such as hearing science. This article presents a brief conceptual overview of selected ML approaches and describes how these techniques are being applied to outstanding problems in hearing science, with a particular focus on auditory evoked potentials (AEPs). Two vignettes are presented in which ML is used to analyze subcortical AEP data. The first vignette demonstrates how ML can be used to determine if auditory learning has influenced auditory neurophysiologic function. The second vignette demonstrates how ML analysis of AEPs may be useful in determining whether hearing devices are optimized for discriminating speech sounds.

Hearing status of people occupationally exposed to ultrasonic noise

OBJECTIVES

The aim of the study was to evaluate the hearing status of operators of low-frequency ultrasonic devices compared to employees exposed to audible noise at a similar A-weighted sound pressure level (SPL) but without ultrasonic components.

MATERIAL AND METHODS

Standard pure-tone audiometry, extended high-frequency audiometry (EHFA), transient-evoked otoacoustic emissions (TEOAE), and distortion-product otoacoustic emissions (DPOAE), as well as questionnaire surveys were conducted among 148 subjects, aged 43.1±10.8 years, working as ultrasonic device operators for 18.7±10.6 years. Their exposure to noise within the ultrasonic and audible frequency range was also evaluated. The control group comprised 168 workers, adjusted according to gender, age (±2 years), tenure (±2 years), and the 8-hour daily noise exposure level (LEX,8h) of ±2 dB.

RESULTS

The ultrasonic device operators and the control group were exposed to audible noise at LEX,8h of 80.8±3.9 dB and 79.1±3.4, respectively. The Polish maximum admissible intensity (MAI) values for audible noise were exceeded in 16.8% of the ultrasonic device operators, while 91.2% of them were exposed to ultrasonic noise at SPL>MAI values. There were no significant differences between the groups in terms of the hearing threshold levels (HTLs) up to 3 kHz, while the ultrasonic device operators exhibited significantly higher (worse) HTLs, as compared to the control group, in the range of 4-14 kHz. The results of the DPOAE and TEOAE testing also indicated worse hearing among the ultrasonic device operators. However, the differences between the groups were more pronounced in the case of EHFA and DPOAEs.

CONCLUSIONS

The outcomes of all hearing tests consistently indicated worse hearing among the ultrasonic device operators as compared to the control group. Both EHFA and DPOAE seem to be useful tools for recognizing early signs of hearing loss among ultrasonic device operators. nt J Occup Med Environ Health. 2022;35(3):309-25.

Ultra-High Frequency Distortion Product Otoacoustic Emissions for Detection of Hearing Loss and Tinnitus

Several studies have suggested that distortion product otoacoustic emissions (DPOAEs) may be an early marker not only of hearing loss (HL) but also of tinnitus. The purpose of this study was to investigate whether DPOAEs measured up to 16 kHz are affected by the presence of tinnitus. Pure tone thresholds and DPOAEs were measured in two groups: 55 patients with tinnitus and 63 subjects without tinnitus. The subjects were divided into three groups according to their audiometric results-better than 25 dB HL at all tested frequencies from 0.125 to 16 kHz, better than 25 dB up to 8 kHz, and hearing impaired. Receiver operator characteristics (ROCs) were used to test whether DPOAEs could differentiate between normal hearing, hearing loss, and tinnitus. Comparison of tinnitus subjects with the control group, matched accurately according to thresholds, did not yield any significant difference in DPOAEs. However, in both these groups hearing loss was accompanied by a decrease in DPOAEs, specifically, at 2-6 kHz and 16 kHz. The results suggest that any decrease in DPOAEs seems to be related only to hearing loss and there is no additional effect from tinnitus.

The Strength of the Medial Olivocochlear Reflex in Chinchillas Is Associated With Delayed Response Performance in a Visual Discrimination Task With Vocalizations as Distractors

The ability to perceive the world is not merely a passive process but depends on sensorimotor loops and interactions that guide and actively bias our sensory systems. Understanding which and how cognitive processes participate in this active sensing is still an open question. In this context, the auditory system presents itself as an attractive model for this purpose as it features an efferent control network that projects from the cortex to subcortical nuclei and even to the sensory epithelium itself. This efferent system can regulate the cochlear amplifier sensitivity through medial olivocochlear (MOC) neurons located in the brainstem. The ability to suppress irrelevant sounds during selective attention to visual stimuli is one of the functions that have been attributed to this system. MOC neurons are also directly activated by sounds through a brainstem reflex circuit, a response linked to the ability to suppress auditory stimuli during visual attention. Human studies have suggested that MOC neurons are also recruited by other cognitive functions, such as working memory and predictability. The aim of this research was to explore whether cognitive processes related to delayed responses in a visual discrimination task were associated with MOC function. In this behavioral condition, chinchillas held their responses for more than 2.5 s after visual stimulus offset, with and without auditory distractors, and the accuracy of these responses was correlated with the magnitude of the MOC reflex. We found that the animals’ performance decreased in presence of auditory distractors and that the results observed in MOC reflex could predict this performance. The individual MOC strength correlated with behavioral performance during delayed responses with auditory distractors, but not without them. These results in chinchillas, suggest that MOC neurons are also recruited by other cognitive functions, such as working memory.

Investigational Medicinal Products for the Inner Ear: Review of Clinical Trial Characteristics in ClinicalTrials.gov

BACKGROUND

The previous 30 years have provided information on the mechanisms of cell death in the inner ear after noise exposure, ototoxic drug injury, and during aging, and clinical trials have emerged for all of these acquired forms of hearing loss. Sudden hearing loss is less well understood, but restoration of hearing after sudden hearing loss is also a long-standing drug target, typically using steroids as an intervention but with other agents of interest as well.

PURPOSE

The purpose of this review was to describe the state of the science regarding clinical testing of investigational medicinal products for the inner ear with respect to treatment or prevention of acquired hearing loss.

DATA COLLECTION AND ANALYSIS

Comprehensive search and summary of clinical trials listed in the National Library of Medicine (www.

CLINICALTRIALS

gov) database identified 61 clinical trials.

RESULTS

Study phase, status, intervention, and primary, secondary, and other outcomes are summarized for studies assessing prevention of noise-induced hearing loss, prevention of drug-induced hearing loss, treatment of stable sensorineural hearing loss, and treatment of sudden sensorineural hearing loss.

CONCLUSION

This review provides a comprehensive summary of the state of the science with respect to investigational medicinal products for the inner ear evaluated in human clinical trials, and the current challenges for the field.

Measuring Distortion-Product Otoacoustic Emission With a Single Loudspeaker in the Ear: Stimulus Design and Signal Processing Techniques

The distortion-product otoacoustic emission (DPOAE) is a backward propagating wave generated inside the cochlea during the wave amplification process. The DPOAE signal can be detected rapidly under relatively noisy conditions. In recent years, the earphone industry demonstrated interest in adopting DPOAE as an add-on feature to make their product “intelligent” of inner-ear status. However, a technical challenge remains to be tackled—the loudspeaker in an earphone generates its own cubic distortion at the same frequency as DPOAE. Unfortunately, the intensity of loudspeaker distortion is typically comparable to that of the DPOAE, if not higher. In this research, we propose two strategies, namely compensation and cancellation, to enable DPOAE measurement with a single loudspeaker. The compensation strategy exploits the part of the growth function of the loudspeaker distortion which is almost linear, and thus suppresses the distortion it generates while retaining a larger portion of DPOAE in the residual signal. The cancellation strategy utilizes a one-dimensional Volterra filter to remove the cubic distortion from the loudspeaker. Testing on normal-hearing ears shows that the compensation strategy improved the DPOAE-to-interference ratio by approximately 7 dB, resulting in a cross-correlation of 0.62 between the residual DPOAE level and the true DPOAE level. Meanwhile, the cancellation strategy directly recovered both the magnitude and the phase of DPOAE, reducing the magnitude estimation error from 15.5 dB to 3.9 dB in the mean-square sense. These pilot results suggest that the cancellation strategy may be suitable for further testing with more subjects.

Keypoints to Successful Newborn Hearing Screening. Thirty Years of Experience and Innovations

Congenital deafness is a major pediatric problem, affecting about 1.5–3 per 1000 newborns. The early treatment through cochlear implantation and auditory rehabilitation has been a historic milestone. Early diagnosis of congenital deafness is an essential requirement to obtain the best results, which is achieved through neonatal screening, a diagnostic practice that we began systematically at the Hospital Clínico in Valencia (Spain) 30 years ago. Neonatal hearing screening is successful in most developed countries. Its implementation has been slow due to the multiple difficulties that its universal application entails since it involves several health professionals and must be carried out, in a short time interval after birth. In addition, it must have a good performance that prevents the overload of other services and that requires experience and continuous adjustments in search of proper protocols. The aim of this review is to shed some light on some key points of neonatal hearing screening, highlighting our experience in the solutions to common problems. We will discuss about techniques, protocols and neonatal or nutritional factors that can influence the screening results. To a summary of our work, an update on the subject is provided with the intention of sharing experiences and facilitating the start-up of the new units.

Auditory biophysics of endolymphatic hydrops

Audiological tests in patients with Menière's disease reveal abnormal patterns relevant for diagnostic purposes with some success. Electrocochleography, otoacoustic emissions and immittance measurements share a moderate sensitivity but a good specificity. Their potential for monitoring the patients suggests means to understand the characteristic time course of Menière's disease and the pathophysiology behind its attacks. Besides, magnetic resonance imaging now allows direct evaluation of endolymphatic hydrops. One issue is now to understand the links between volume inflation of endolymphatic spaces, which sometimes remains asymptomatic, and the functional signs, in the hope that a better understanding of what triggers the attacks may guide future treatments. This article provides a short review of the possible biophysical significance of audiological tests of Menière's disease, and of the attempts to make sense of functional and imaging data and of the patterns they form when combined.

Otoferlin Is Required for Proper Synapse Maturation and for Maintenance of Inner and Outer Hair Cells in Mouse Models for DFNB9

Deficiency of otoferlin causes profound prelingual deafness in humans and animal models. Here, we closely analyzed developmental deficits and degenerative mechanisms in Otof knock-out (Otof^–/–) mice over the course of 48 weeks. We found otoferlin to be required for proper synapse development in the immature rodent cochlea: In absence of otoferlin, synaptic pruning was delayed, and postsynaptic boutons appeared enlarged at 2 weeks of age. At postnatal day 14 (P14), we found on average ∼15 synapses per inner hair cell (IHC) in Otof^–/– cochleae as well as in wild-type controls. Further on, the number of synapses in Otof^–/– IHCs was reduced to ∼7 at 8 weeks of age and to ∼6 at 48 weeks of age. In the same period, the number of spiral ganglion neurons (SGNs) declined in Otof^–/– animals. Importantly, we found an age-progressive loss of IHCs to an overall number of 75% of wildtype IHCs. The IHC loss more prominently but not exclusively affected the basal aspects of the cochlea. For outer hair cells (OHCs), we observed slightly accelerated age-dependent degeneration from base to apex. This was associated with a progressive decay in DPOAE amplitudes for high frequency stimuli, which could first be observed at the age of 24 weeks in Otof^–/– mice. Our data will help to plan and predict the outcome of a gene therapy applied at various ages of DFNB9 patients.

Comparison of Behavioral and Physiological Measures of the Status of the Cochlear Nonlinearity

While an audiogram is a useful method of characterizing hearing loss, it has been suggested that including a complementary, suprathreshold measure, for example, a measure of the status of the cochlear active mechanism, could lead to improved diagnostics and improved hearing-aid fitting in individual listeners. While several behavioral and physiological methods have been proposed to measure the cochlear-nonlinearity characteristics, evidence of a good correspondence between them is lacking, at least in the case of hearing-impaired listeners. If this lack of correspondence is due to, for example, limited reliability of one of such measures, it might be a reason for limited evidence of the benefit of measuring peripheral compression. The aim of this study was to investigate the relation between measures of the peripheral-nonlinearity status estimated using two psychoacoustical methods (based on the notched-noise and temporal-masking curve methods) and otoacoustic emissions, on a large sample of hearing-impaired listeners. While the relation between the estimates from the notched-noise and the otoacoustic emissions experiments was found to be stronger than predicted by the audiogram alone, the relations between the two measures and the temporal-masking based measure did not show the same pattern, that is, the variance shared by any of the two measures with the temporal-masking curve-based measure was also shared with the audiogram.

Analysis of the Referral Rates of Newborn Hearing Screening Test According to Childbirth Delivery Methods in Neonatal Care Units

It is known that neonates born by cesarean delivery (CD) may have higher referral rates than those born by vaginal delivery (VD) for newborn hearing screening (NHS). False-positive NHS results can increase costs and parental anxiety. This study analyzed the differences in NHS referral rates according to delivery methods in Level I, II, and III neonatal care units. A retrospective chart review was done for 2322 infants (4644 ears) with delivery records who underwent NHS between 2004 and 2017. The first NHS was performed immediately before discharge when the infant was in good condition via the automated auditory brainstem response (AABR) or automated otoacoustic emissions (AOAE). There were 98 neonates (196 ears) who underwent both AABR and AOAE simultaneously as the first NHS, 30 of which failed. We used a total of 4810 ears in this analysis. Of all enrolled ears, 2075 ears were of neonates born by CD, and 2735 ears were of neonates born by VD. A total of 2460 ears were from patients in Level III neonatal intensive care units (NICU) and 2350 ears were from Level I and II neonatal care units. The overall referral rate was higher in infants born via CD (4.5%) than VD (3.2%). In Level I and II neonatal intensive care units, the referral rate was significantly higher in those born via CD (3.0%) than via VD (1.4%). Further, based on the screening method, AABR (75.8%) was more frequently used than AOAE (24.2%), thereby revealing AABR’s higher referral rate in CD (2.9%) than in VD (1.2%). The referral rate of infants who underwent the NHS within three days of birth was higher in the CD group (3.0%) than in the VD group (1.3%). There was no significant difference in the referral rate depending on the delivery method when infants were hospitalized for more than four days or hospitalized in the NICU. The referral rate according to the delivery methods was significantly higher when the NHS test was performed for healthy newborns in the Level I and II neonatal care units born by CD within 72 h using AABR. Therefore, we recommend that the hearing screening test for newborns delivered by cesarean section be performed after 72 h of age. The results of this study may reduce the false-positive NHS results, unnecessary further tests, and parental anxiety.

Decentralising paediatric hearing services through district healthcare screening in Western Cape province, South Africa

Background

Childhood hearing loss is a global epidemic most prevalent in low- and middle-income countries where hearing healthcare services are often inaccessible. Referrals for primary care services to central hospitals add to growing lists and delays the time-sensitive treatment of childhood hearing loss.

Aim

To compare a centralised tertiary model of hearing healthcare with a decentralised model through district hearing screening for children in the Western Cape province, South Africa.

Setting

A central paediatric tertiary hospital in Cape Town and a district hospital in the South Peninsula region.

Methods

A pragmatic quasi-experimental study design was used with a 7-month control period at a tertiary hospital (June 2019 to December 2019). Decentralising was measured by attendance rates, travelling distance, number of referrals to the tertiary hospital and hearing outcomes. There were 315 children in the tertiary group and 158 in the district group. Data were collected from patient records and an electronic database at the tertiary hospital.

Results

Attendance rate at the district hospital was significantly higher (p < 0.001). Travel distance to the district hospital was significantly shorter (p < 0.001). Number of referrals to the tertiary hospital decreased significantly during the intervention period (p < 0.001). Most children in both the tertiary and district groups (78.7% and 80.4%, respectively) passed initial hearing screening bilaterally.

Conclusion

Hearing screening should be conducted at the appropriate level of care to increase access, reduce patient travelling distances and associated costs and reduce the burden on tertiary-level hospitals.

Spatiotemporal Developmental Upregulation of Prestin Correlates With the Severity and Location of Cyclodextrin-Induced Outer Hair Cell Loss and Hearing Loss

2-Hyroxypropyl-beta-cyclodextrin (HPβCD) is being used to treat Niemann-Pick C1, a fatal neurodegenerative disease caused by abnormal cholesterol metabolism. HPβCD slows disease progression, but unfortunately causes severe, rapid onset hearing loss by destroying the outer hair cells (OHC). HPβCD-induced damage is believed to be related to the expression of prestin in OHCs. Because prestin is postnatally upregulated from the cochlear base toward the apex, we hypothesized that HPβCD ototoxicity would spread from the high-frequency base toward the low-frequency apex of the cochlea. Consistent with this hypothesis, cochlear hearing impairments and OHC loss rapidly spread from the high-frequency base toward the low-frequency apex of the cochlea when HPβCD administration shifted from postnatal day 3 (P3) to P28. HPβCD-induced histopathologies were initially confined to the OHCs, but between 4- and 6-weeks post-treatment, there was an unexpected, rapid and massive expansion of the lesion to include most inner hair cells (IHC), pillar cells (PC), peripheral auditory nerve fibers, and spiral ganglion neurons at location where OHCs were missing. The magnitude and spatial extent of HPβCD-induced OHC death was tightly correlated with the postnatal day when HPβCD was administered which coincided with the spatiotemporal upregulation of prestin in OHCs. A second, massive wave of degeneration involving IHCs, PC, auditory nerve fibers and spiral ganglion neurons abruptly emerged 4–6 weeks post-HPβCD treatment. This secondary wave of degeneration combined with the initial OHC loss results in a profound, irreversible hearing loss.

Effect of analgesia with pethidine during labour on false positivity of newborn hearing screening test

OBJECTIVES

Newborn hearing screening may fail due to some perinatal and neonatal factors. False positivity of newborn hearing screening increases costs, familial concerns and anxiety. The objective of this study was to determine the effects of pethidine administered in the mother for labor analgesia on the false positivity rates of the newborn hearing screening test.

METHODS

This study was designed as a retrospective and cross-sectional study. A total of 75 pregnant women scheduled for vaginal delivery who received 50 mg intramuscular pethidine at the beginning of the active phase of the labor were included as the patient group and 68 pregnant women who did not receive pethidine as the control group. A total of 143 infants born with vaginal delivery were evaluated with otoacoustic emission (OAE) test before discharge. Perinatal and neonatal variables and test outcomes were recorded, and the correlation between false positivity rate and pethidine usage was evaluated.

RESULTS

Initially, system records of 148 healthy term newborns were screened. Four patients who failed in both OAE tests and were referred to the Automated Auditory Brainstem Response (AABR) test and one patient who failed in all tests (first OAE, control OAE and AABR) and was referred to an upper center for further investigations and treatment were excluded from the study. No statistically significant difference was found between the groups in terms of birth features. First stage OAE test was reported as 'passed' in 8 (10.7%) and 58 (85.3%) newborns in the study and control groups, respectively; while OAE was reported as 'referred' and 'passed' in the second test in 67 (89.3%) and 10 (14.7%) newborns in the study and control groups, respectively. There was a statistically significant difference between both groups in terms of false positivity ratio (p < 0.5).

CONCLUSION

Pethidine significantly decreases the duration of the active phase, providing a good analgesic effect for pain management during labor. Therefore, it seems that pethidine can be used as an acceptable agent during labor. However, it may have neonatal effects after the delivery, causing false positivity in newborn hearing screening tests. The results of this study support the opinion that the OAE test should be performed in postpartum later dates in order to increase OAE passing rates and minimize costs and parents' concerns.

Assessment of the Hearing Status of School-Age Children from Rural and Urban Areas of Mid-Eastern Poland

(1) Background: The purpose of this study was to assess the prevalence of hearing loss in school-age children from rural and urban areas of mid-eastern Poland using standard audiological tests-pure tone audiometry (PTA), impedance audiometry (IA), and otoacoustic emissions (OAEs). (2) Methods: Data were collected from a group of 250 children aged 8 to 13, made up of 122 children from urban areas and 128 children from rural areas of mid-eastern Poland. Hearing was assessed in each of the subjects by means of PTA, IA (tympanometry), and transient-evoked OAEs (TEOAEs). Otoscopy was also performed. (3) Results: There were significantly fewer abnormal results in children from urban than rural areas: they were, respectively, 10.1% and 23.1% for IA, 3% and 9.7% for PTA, and 17.3% and 31.8% for TEOAEs. For hearing-impaired ears in rural areas (failed TEOAE), hearing thresholds were, on average, 11.5 dB higher at 0.5 kHz than for children in urban areas. Comparison of each PTA result with the corresponding IA showed that all cases of hearing loss were related to malfunction of the middle ear. (4) Conclusions: The results of all three hearing tests were significantly worse in children from rural areas compared to those from urban areas. This indicates that audiological healthcare in rural areas needs improvement and that universal hearing screening programs for school-age children would be helpful.

Factors Affecting Neonatal Hearing Screening Follow-up in Developing Countries: One Insitution Prospective Pilot Study

Objective

To detect factors related with loss to follow-up (LTF) in neonatal hearing screening (NHS) program of one institution in a developing country.

Methods

A prospective study was planned based on the data collected in a pilot study conducted a year before in the same institution. In this pilot study, hearing screening was performed before hospital discharge for every infant (1217 newborns) in six months period. Total referral rate was 19.1% (223/1217). Loss to follow-up (LTF) was 38.1% (85/223). Telephonic interviews were done with 50 parents who had not come with their child to the second hearing test. For these telephonic interviews the questionnaire with four sections (socio-demographic information; information about pregnancy, birth, and present health condition of the child; caregiver knowledge of neonatal hearing screening, and reasons for default on follow-up) was created.

Results

The mothers participated in this study were 29.1 years (±5.2 SD) of age in average. Place of residence was mostly rural (64%; n=32) with 39.4 Km (±24.8 SD) away from from the rescreen referral center. Their knowledge on neonatal hearing screening, hearing impairment incidence or treatment opportunities was at a very low level. Caregivers’ perceptions that follow-up was unnecessary (50%; n=25), was most frequently given reason for follow-up default, followed by newborns bad health condition (12%; n=6) and forgetting about the follow-up visits (8%; n=6).

Conclusion

The main reason for default in follow-up in our study was caregiver’s poor knowledge about this topic.

Medial olivocochlear reflex effects on amplitude growth functions of long- and short-latency components of click-evoked otoacoustic emissions in humans

Functional outcomes of medial olivocochlear reflex (MOCR) activation, such as improved hearing in background noise and protection from noise damage, involve moderate to high sound levels. Previous noninvasive measurements of MOCR in humans focused primarily on otoacoustic emissions (OAEs) evoked at low sound levels. Interpreting MOCR effects on OAEs at higher levels is complicated by the possibility of the middle-ear muscle reflex and by components of OAEs arising from different locations along the length of the cochlear spiral. We overcame these issues by presenting click stimuli at a very slow rate and by time-frequency windowing the resulting click-evoked (CE)OAEs into short-latency (SL) and long-latency (LL) components. We characterized the effects of MOCR on CEOAE components using multiple measures to more comprehensively assess these effects throughout much of the dynamic range of hearing. These measures included CEOAE amplitude attenuation, equivalent input attenuation, phase, and slope of growth functions. Results show that MOCR effects are smaller on SL components than LL components, consistent with SL components being generated slightly basal of the characteristic frequency region. Amplitude attenuation measures showed the largest effects at the lowest stimulus levels, but slope change and equivalent input attenuation measures did not decrease at higher stimulus levels. These latter measures are less commonly reported and may provide insight into the variability in listening performance and noise susceptibility seen across individuals.NEW & NOTEWORTHY The auditory efferent system, operating at moderate to high sound levels, may improve hearing in background noise and provide protection from noise damage. We used otoacoustic emissions to measure these efferent effects across a wide range of sound levels and identified level-dependent and independent effects. Previous reports have focused on level-dependent measures. The level-independent effects identified here may provide new insights into the functional relevance of auditory efferent activity in humans.

Muscles in and around the ear as the source of "physiological noise" during auditory selective attention: A review and novel synthesis

The sensitivity of the auditory system is regulated via two major efferent pathways: the medial olivocochlear system that connects to the outer hair cells, and by the middle ear muscles-the tensor tympani and stapedius. The role of the former system in suppressing otoacoustic emissions has been extensively studied, but that of the complementary network has not. In studies of selective attention, decreases in otoacoustic emissions from contralateral stimulation have been ascribed to the medial olivocochlear system, but the acknowledged problem is that the results can be confounded by parallel muscle activity. Here, the potential role of the muscle system is examined through a wide but not exhaustive review of the selective attention literature, and the unifying hypothesis is made that the prominent "physiological noise" detected in such experiments, which is reduced during attention, is the sound produced by the muscles in proximity to the ear-including the middle ear muscles. All muscles produce low-frequency sound during contraction, but the implications for selective attention experiments-in which muscles near the ear are likely to be active-have not been adequately considered. This review and synthesis suggests that selective attention may reduce physiological noise in the ear canal by reducing the activity of muscles close to the ear. Indeed, such an experiment has already been done, but the significance of its findings have not been widely appreciated. Further sets of experiments are needed in this area.

Efferent unmasking of speech-in-noise encoding?

OBJECTIVE

The medial olivocochlear (MOC) reflex provides efferent feedback from the brainstem to cochlear outer hair cells. Physiologic studies have demonstrated that the MOC reflex is involved in "unmasking" of signals-in-noise at the level of the auditory nerve; however, its functional importance in human hearing remains unclear.

DESIGN

This study examined relationships between pre-neural measurements of MOC reflex strength (click-evoked otoacoustic emission inhibition; CEOAE) and neural measurements of speech-in-noise encoding (speech frequency following response; sFFR) in four conditions (Quiet, Contralateral Noise, Ipsilateral Noise, and Ipsilateral + Contralateral Noise). Three measures of CEOAE inhibition (amplitude reduction, effective attenuation, and input-output slope inhibition) were used to quantify pre-neural MOC reflex strength. Correlations between pre-neural MOC reflex strength and sFFR "unmasking" (i.e. response recovery from masking effects with activation of the MOC reflex in time and frequency domains) were assessed.

STUDY SAMPLE

18 young adults with normal hearing.

RESULTS

sFFR unmasking effects were insignificant, and there were no correlations between pre-neural MOC reflex strength and sFFR unmasking in the time or frequency domain.

CONCLUSION

Our results do not support the hypothesis that the MOC reflex is involved in speech-in-noise neural encoding, at least for features that are represented in the sFFR at the SNR tested.

Comparison of Two-Step Transient Evoked Otoacoustic Emissions and One-Step Automated Auditory Brainstem Response for Universal Newborn Hearing Screening Programs in Remote Areas of China

Objective: To compare the hearing screening results of two-step transient evoked otoacoustic emissions (TEOAE) and one-step automatic auditory brainstem response (AABR) in non-risk newborns, and to explore a more suitable hearing screening protocol for infants discharged within 48 h after birth in remote areas of China. Methods: To analyze the age effect on pass rate for hearing screening, 2005 newborns were divided into three groups according to screening time after birth: <24, 24-48, and 48-72 h. All subjects received TEOAE + AABR test as first hearing screen, and those who failed in any test were rescreened with TEOAE + AABR at 6 weeks after birth. The first screening results of AABR and TEOAE were compared among the three groups. The results of two-step TEOAE screening and one-step AABR screening were compared for newborns who were discharged within 48 h. The time spent on screening was recorded for TEOAE and AABR. Results: The pass rate of TEOAE and AABR increased significantly with the increase of first screening time (P < 0.05), and the false positive rate decreased significantly with the increase of first screening time (P < 0.05). The failure rate of first screening of AABR within 48 h was 7.31%, which was significantly lower than that of TEOAE (9.93%) (P < 0.05). The average time spent on AABR was 12.51 ± 6.36 min, which was significantly higher than that of TEOAE (4.05 ± 1.56 min, P < 0.05). The failure rate of TEOAE two-step screening was 1.59%, which was significantly lower than one-step AABR. Conclusions: Compared with TEOAE, AABR screening within 48 h after birth can reduce the failure rate and false positive rate of first screening. However, compared with TEOAE two-step screening, one-step AABR screening has higher referral rate for audiological diagnosis. In remote areas of China, especially in hospitals with high delivery rate, one-step AABR screening is not feasible, and two-step TEOAE screening protocol is still applicable to UNHS screening as more and more infants discharged within 48 h after birth.

Occupational Noise: Auditory and Non-Auditory Consequences

Occupational noise exposure accounts for approximately 16% of all disabling hearing losses, but the true value and societal costs may be grossly underestimated because current regulations only identify hearing impairments in the workplace if exposures result in audiometric threshold shifts within a limited frequency region. Research over the past several decades indicates that occupational noise exposures can cause other serious auditory deficits such as tinnitus, hyperacusis, extended high-frequency hearing loss, and poor speech perception in noise. Beyond the audiogram, there is growing awareness that hearing loss is a significant risk factor for other debilitating and potentially life-threatening disorders such as cardiovascular disease and dementia. This review discusses some of the shortcomings and limitations of current noise regulations in the United States and Europe.

No Change in Medial Olivocochlear Efferent Activity during an Auditory or Visual Task: Dual Evidence from Otoacoustic Emissions and Event-Related Potentials

The medial olivocochlear (MOC) system is thought to be responsible for modulation of peripheral hearing through descending (efferent) pathways. This study investigated the connection between peripheral hearing function and conscious attention during two different modality tasks, auditory and visual. Peripheral hearing function was evaluated by analyzing the amount of suppression of otoacoustic emissions (OAEs) by contralateral acoustic stimulation (CAS), a well-known effect of the MOC. Simultaneously, attention was evaluated by event-related potentials (ERPs). Although the ERPs showed clear differences in processing of auditory and visual tasks, there were no differences in the levels of OAE suppression. We also analyzed OAEs for the highest magnitude resonant mode signal detected by the matching pursuit method, but again did not find a significant effect of task, and no difference in noise level or number of rejected trials. However, for auditory tasks, the amplitude of the P3 cognitive wave negatively correlated with the level of OAE suppression. We conclude that there seems to be no change in MOC function when performing different modality tasks, although the cortex still remains able to modulate some aspects of MOC activity.

Pharmaco-Audiology Vigilance in the Treatment of Adult Patients with HIV/Aids: Ototoxicity Monitoring Protocol Recommendation

South Africa is considered the epicenter of HIV/AIDS with a high rate of TB infection as well. Links have been established between treatments of these conditions to ototoxicity. However, no standardized and systematic ototoxicity monitoring exists within the clinical sites where these conditions are treated, with very minimal and adhoc involvement of audiologists as part of the treatment team. With 3.4 million HIV-infected South Africans being reported to have been on antiretroviral drugs by the end of March 2016; with universal coverage being the target, it is important that ototoxicity monitoring becomes part of the treatment plan. The objective of the current paper is to propose an ototoxicity monitoring protocol that can be implemented within this population to ensure that systematic data are collated in order for evidence-based protocols to be adopted within the South African context. Such a protocol will also allow for early identification and intervention of ototoxic hearing loss within this population. Enough evidence exists to support implementation of standardized protocols that will allow for proper, accurate, efficient, and reliable comparisons of data within and between patients; as well as between and within treatment sites - both locally and internationally. It is hoped that implementation of such a monitoring protocol will also have significant implications for the expanded role of the audiologist in the drug development process, affording evidence-based benefit-risk assessments of drugs in the market for this population.

Lateralization of cochlear dysfunction as a specific biomarker of Parkinson's disease

In the last decade, animal studies highlighted the sensitivity of hearing function to lack of specific cochlear dopamine receptors, while several studies on humans reported association between hearing loss and Parkinson's disease, partially recovered after levodopa administration in de novo patients. Taken together, these observations suggest investigating the possible use of cochlear function outcome variables, particularly, otoacoustic emissions, as sensitive biomarkers of Parkinson's disease. Any lateralization of hearing dysfunction correlated with Parkinson's disease lateralization would (i) further confirm their association and (ii) provide a disease-specific differential outcome variable. Differential indicators are particularly useful for diagnostic purposes, because their effectiveness is not limited by physiological inter-subject fluctuations of the outcome variable. Recent advances in the acquisition and analysis techniques of otoacoustic emissions suggest using them for evaluating differential cochlear damage in the two ears. In this study, we quantitatively evaluated hearing function in a population of subjects with Parkinson's disease, to investigate the occurrence of hearing loss, and, particularly, whether hearing dysfunction shows lateralization correlated with motor symptoms. Pure tone audiometry and distortion product otoacoustic emissions were used as outcome variables in 80 patients (mean age 65 ± 9 years) and 41 controls (mean age 64 ± 10 years). An advanced customized acquisition and analysis system was developed and used for otoacoustic testing, which guarantees response stability independent of probe insertion depth, and has the sensitivity necessary to accurately assess the low levels of otoacoustic response typical of elderly subjects. To our knowledge, this is the first study introducing the distinction between ipsilateral and contralateral ear, with respect to the body side more affected by Parkinson's disease motor symptoms. Significant asymmetry was found in the auditory function, as both otoacoustic responses and audiometric hearing levels were worse in the ipsilateral ear. Significantly worse hearing function was also observed in patients with Parkinson's disease compared to controls, confirming previous studies. Several pathophysiological mechanisms may be hypothesized to explain asymmetric cochlear damage in Parkinson's disease, including the impairment of dopamine release and the involvement of extra-dopaminergic circuits, with the cholinergic pathway as a likely candidate. The observed asymmetry in the audiological response of patients with Parkinson's disease suggests that lateralization of hearing dysfunction could represent a specific non-motor signature of the disease. The possible diagnostic use of cochlear dysfunction asymmetry as a specific biomarker of Parkinson's disease deserves further investigation, needing a more precise quantitative assessment, which would require a larger sample size.

Breastfeeding results in better hearing in newborns compared to bottle-feeding

BACKGROUND AND AIM

Transient evoked otoacoustic emissions (TEOAEs) are a validated technique in newborn hearing screening that is regularly used in many countries. It reflects normal hearing or at least no more than 30 dB HL hearing loss. Breastfeeding has many advantages and some studies have demonstrated that it prevents otitis media by means of opening the Eustachian tube and clearing mucus in the middle ear which is perhaps also combined with immunological effects. A few studies have related how newborn feeding can vary the pass rate to TEOAE. The goal of this study was to investigate the relationship between newborn feeding and TEOAE newborn hearing screening results.

METHODS

Data were retrospectively collected from healthy vaginally delivered newborns of gestational age >37 weeks and body weight > 2.5 kg at the maternity ward. Newborn feeding history was compared with the pass rate to TEOAE performed within the 1st 48 h of life.

RESULTS

The study group included 12,866 newborns. In this group, significant differences were found based on the feeding method (breastfeeding was found to be better than formula, P<0.0001).

CONCLUSIONS

Breastfeeding improves newborn hearing screening results with TEOAE.

RELEVANCE FOR PATIENTS

Lies in the fact that breastfed children respond better to the test and need to repeat it fewer times, avoiding problems such as loss to follow-up and additional work.

Does noise exposure during pregnancy affect neonatal hearing screening results?

Objective

The aim is to investigate whether noise is effective on hearing screening tests of neonates born to mothers exposed to noise during pregnancy.

Material and Method

Screening results of 2653 infants from the period of January 2013-May 2017 were evaluated. Transient Evoked Otoacoustic Emissions (TEOAE) and Auditory Brainstem Response (ABR) were used. Infants of 65 mothers exposed to noise (L_Aeq 80-85 dBA/8 hours/day) during pregnancy (Week ± SD; 32.58 ± 2.71) comprised the study group while the control group consisted of infants of 2588 mothers without noise exposure.

Results

Among the 65 infants, 23 (35.4%) passed screening at the first emission test (OAE1); 34 (52.3%) at the second emission test (OAE2); 7 (10.8%) at the ABR stage, 1 (1.5%) infant was referred to a tertiary center. In the control group, 458 (17.7%) infants passed at OAE1; 1822 (70.4%) at OAE2; 289 (11.2%) at ABR stages, 19 (0.7%) infants were referred to a tertiary center. The rate of infants that passed screening at OAE1 in the study group was high (P = 0.00001). Sixty-four (98.46%) infants in the study group and 2569 (99.26%) infants in the control group passed the tests. The difference between the two groups was not significant, indicating that exposure to noise during pregnancy had no unfavorable effects on auditory functions (P = 0.392).

Conclusion

Unfavorable effect of noise exposure during pregnancy was not observed on auditory functions of the infants. The higher rate of infants that passed the screening test at OAE1 stage in the study group raised the question, "Does the exposure of the noise at exposure action levels (80-85 dB A) during pregnancy contribute to auditory maturation of fetus?"

Future Perspectives on the Relevance of Auditory Markers in Prodromal Parkinson's Disease

Research on auditory processing in Parkinson's disease (PD) has recently made substantial progress. At present, evidence has been found for altered auditory processing in the clinical stage of PD. The auditory alterations in PD have been demonstrated with low-cost and non-invasive assessments that are already used in routine clinical practice. Since auditory alterations have been reported early in disease progression, it would be highly relevant to investigate whether auditory markers could be provided in the prodromal stage of PD. In addition, auditory alterations in early stage PD might be modulated by dopaminergic medication. Therefore, the aim of this review is (1) to summarize the literature on auditory processing in PD with a specific focus on the early disease stages, (2) to give future perspectives on which audiological and electrophysiological measurements could be useful in the prodromal stage of PD and (3) to assess the effect of dopaminergic medication on potential auditory markers in the prodromal stage of PD.

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.