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Many aspects of stress-induced physiological and psychological effects have been characterized in people and animals. However, stress effects on the auditory system are less explored and their mechanisms are not well-understood, in spite of its relevance for a variety of diseases, including tinnitus. To expedite further research of stress-induced changes in the auditory system, here we compare the reactions to stress among Wistar and Lewis rats. The animals were stressed for 24 h, and subsequently we tested the functionality of the outer hair cells (OHCs) using distortion product otoacoustic emissions (DPOAEs) and auditory neurons using evoked auditory brainstem responses (ABR). Lastly, using Western blot, we analyzed the levels of plasticity-related proteins in the inferior colliculus, confirming that the inferior colliculus is involved in the adaptive changes that occur in the auditory system upon stress exposure. Surprisingly, the two strains reacted to stress quite differently: Lewis rats displayed a lowering of their auditory threshold, whereas it was increased in Wistar rats. These functional differences were seen in OHCs of the apical region (low frequencies) and in the auditory neurons (across several frequencies) from day 1 until 2 weeks after the experimental stress ended. Wistar and Lewis rats may thus provide models for auditory threshold increase and decrease, respectively, which can both be observed in different patients in response to stress.

Introduction: Patients that are complaining from tinnitus but have normal hearing comprise an uncommon group and there is rare literature about them. Deficiency in B-complex vitamins has been shown to result in tinnitus and supplementation may improve the symptom which means manipulation of cochlear status. Distortion Product Otoacoustic emissions (DPOAEs) used frequently to assess cochlear status., Objectives: The uses of DPOAE changing amplitude as a parameter to estimate effect of vitamin B complex on changing the severity of tinnitus in patients with tinnitus only in comparison to patients have tinnitus with Sensory Neural Hearing Loss (SNHL) and a control group., Methods: Prospective observational cohort study was performed in AL-Karama Teaching Hospital as a secondary medical care center, from 01/01/2012 to 31/12/2016. A three groups had been evaluated clinically and by OAE device (ECHOLAB) to study the DPOAE changing amplitude before and after one month of supplementation of B-complex vitamins to 25 patients in study group (1) have (tinnitus only) and also to 25 patients in study group (2) have (Tinnitus + SNHL) but leaving control group who were a 25 medical staff (No Tinnitus and nor SNHL) without treatment., Results: It has been found that among Study group 1 (patients had Tinnitus only), Study group 2 (patients had Tinnitus + SNHL) and the control group: 16 patients (44%), P-value = 0.000 HS; 28 patients (78%) P-value = 0.000 HS; and 0% respectively, they had low Amplitude of DPOAE recorded by OAE device (ECHOLAB). After one month from treatment with Neurobine ampules for study group 1& 2 but not control group (whom receive no treatment), those who got clinical improvement + increase Amplitude of DPOAE (i.e. subjective + objective changes) after treatment were 10 patients (28%) P-value = 0.000 HS in study group1, and two patients (5%) P-value 0.321 NS in study group 2, and there was no changes (zero) among control group., Conclusions: The uses of DPOAE changing amplitude could be used as a parameter to estimate effect of vitamin B complex on changing the severity of Tinnitus in patients with tinnitus only or those have Tinnitus with SNHL. The supplementation of vitamin B complex could improve the tinnitus severity especially in patients with tinnitus without SNHL.

Background: Seven hundred children were recalled for hearing screening at age 2-3 years due to a problem with their newborn hearing screen. They had all been well babies with no identified risk factors for hearing loss and hence were not scheduled for targeted follow-up to retest hearing., Methods: There were 485 children (69%) that attended the recall. The average age was 36 months (SD 3.7). Family ethnicity was Pacific Island (36%), Asian (26%), NZ European (13%), and Māori (11%), and there was a high level of deprivation in the study population. Children were screened using distortion product otoacoustic emission (DPOAE) and a parent or caregiver completed a 14-item questionnaire about ear health. The children that did not pass screening were given appointments for audiology testing. Children with hearing loss and/or middle ear problems were referred for otolaryngology review and further hearing assessments., Results: About one third (36%; n = 176) of children did not pass DPOAE screening; 82 (17%) had abnormal type B tympanograms and hearing loss; 29 underwent insertion of ventilation tubes, and one had a perforated tympanic membrane. There was a significant association between failed tympanometry and hearing loss (Chi-squared = 16.67, p < .001). Five children had permanent sensorineural hearing loss (SNHL), two of whom required cochlear implants for idiopathic hearing loss, with no specific risk factors. Overall 380 of 485 children screened were deemed to have normal hearing (i.e. 22% failed hearing). From the questionnaire, 15% of the caregivers with no suspicion of hearing problems did have children with significant hearing loss. Regression analysis showed that Pacific/Māori ethnicity was significantly associated with risk of hearing loss, together with questionnaire items identifying hearing problems and breathing problems., Conclusions: There is a high proportion of children in South Auckland with unsuspected hearing loss; a different approach to hearing screening is warranted for this population with high rates of middle ear disease at age 3., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Previous research on distortion product otoacoustic emission (DPOAE) components has hinted at possible differences in the effect of aging on the two basic types of OAEs: those generated by a reflection mechanism in the cochlea and those created by nonlinear distortion (Abdala and Dhar in J Assoc Res Otolaryngol 13:403-421, 2012). This initial work led to the hypothesis that micromechanical irregularity ("roughness") increases in the aging cochlea, perhaps as the result of natural tissue degradation. Increased roughness would boost the backscattering of traveling waves (i.e., reflection emissions) while minimally impacting DPOAEs. To study the relational effect of aging on both types of emissions and address our hypothesis of its origin, we measured reflection- and distortion-type OAEs in 77 human subjects aged 18-76 years. The stimulus-frequency OAE (SFOAE), a reflection emission, and the distortion component of the DPOAE, a nonlinear distortion emission, were recorded at multiple stimulus levels across a four-octave range in all ears. Although the levels of both OAE types decreased with age, the rate of decline in OAE level was consistently greater for DPOAEs than for SFOAEs; that is, SFOAEs are relatively preserved with advancing age. Multiple regression analyses and other controls indicate that aging per se, and not hearing loss, drives this effect. Furthermore, SFOAE generation was simulated using computational modeling to explore the origin of this result. Increasing the amount of mechanical irregularity with age produced an enhancement of SFOAE levels, providing support for the hypothesis that increased intra-cochlear roughness during aging may preserve SFOAE levels. The characteristic aging effect-relatively preserved reflection-emission levels combined with more markedly reduced distortion-emission levels-indicates that SFOAE magnitudes in elderly individuals depend on more than simply the gain of the cochlear amplifier. This relative pattern of OAE decline with age may provide a diagnostic marker for aging-related changes in the cochlea.

Sensory axon T-like branching (bifurcation) in neurons from dorsal root ganglia and cranial sensory ganglia depends on the molecular signaling cascade involving the secreted factor C-type natriuretic peptide, the natriuretic peptide receptor guanylyl cyclase B (GC-B; also known as Npr2) and cGMP-dependent protein kinase I (cGKI, also known as PKGI). The bifurcation of cranial nerves is suggested to be important for information processing by second-order neurons in the hindbrain or spinal cord. Indeed, mice with a spontaneous GC-B loss of function mutation ( Npr2 cn/cn ) display an impaired bifurcation of auditory nerve (AN) fibers. However, these mice did not show any obvious sign of impaired basal hearing. Here, we demonstrate that mice with a targeted inactivation of the GC-B gene (Npr2 lacZ/lacZ , GC-B KO mice) show an elevation of audiometric thresholds. In the inner ear, the cochlear hair cells in GC-B KO mice were nevertheless similar to those from wild type mice, justified by the typical expression of functionally relevant marker proteins. However, efferent cholinergic feedback to inner and outer hair cells was reduced in GC-B KO mice, linked to very likely reduced rapid efferent feedback. Sound-evoked AN responses of GC-B KO mice were elevated, a feature that is known to occur when the efferent axo-dendritic feedback on AN is compromised. Furthermore, late sound-evoked brainstem responses were significantly delayed in GC-B KO mice. This delay in sound response was accompanied by a weaker sensitivity of the auditory steady state response to amplitude-modulated sound stimuli. Finally, the acoustic startle response (ASR) - one of the fastest auditory responses - and the prepulse inhibition of the ASR indicated significant changes in temporal precision of auditory processing. These findings suggest that GC-B-controlled axon bifurcation of spiral ganglion neurons is important for proper activation of second-order neurons in the hindbrain and is a prerequisite for proper temporal auditory processing likely by establishing accurate efferent top-down control circuits. These data hypothesize that the bifurcation pattern of cranial nerves is important to shape spatial and temporal information processing for sensory feedback control.

Objective: To investigate the diagnostic value of distortion product otoacoustic emission (DPOAE) together with tympanometry in assessing otitis media with effusion in children., Methods: Three hundred and thirty-nine patients, who were diagnosed with obstructive sleep apnea-hypopnea syndrome (OSAHS) and prepared to undergo adenotonsillectomy and had a unilateral or bilateral type 'B' or 'C' tympanogram were enrolled in this study. Patients were divided into the following four groups: Group 1, type 'B' tympanogram with positive DPOAE; Group 2, type 'B' tympanogram with negative DPOAE; Group 3, type 'C' tympanogram with positive DPOAE and Group 4, type 'C' tympanogram with negative DPOAE., Results: Tympanometry showed a type 'B' pattern in 467 ears and type 'C' pattern in 163 ears. Among 163 ears with type 'C' tympanogram, negative DPOAE results were seen in 96 ears. Group 4 (56/96) had a significant high rate of middle ear effusion than Group 3 (14/67) (p < .05). In patients with a type 'C' tympanogram, those with a low compliance value (∼0.25 ml), concurrent chronic tonsillitis and large tonsils are likely to have middle ear effusion., Conclusions: DPOAE could be a great help in screening for middle ear effusion in patients with a type 'C' tympanogram.

Objective: The use of Mesna as a chemical dissector in higher concentrations may reduce the length of time of operation by providing more effective dissection as well as being used in otologic pathologies such as tympanosclerosis. In this study, it was aimed to assess the effect of Mesna on the internal ear, which was applied intra-tympanically in higher concentrations than the conventional use., Methods: Twenty-four female rats were included in our study. The rats were randomly divided into three groups (Group 1: Mesna 50%, Group 2: Mesna 100%, Group 3: Saline). At the beginning of the study, DPOAE and ABR measurements were carried out on every rat on days 7 and 14. At the end of the study, cochleas of the rats were excised and histopathological assessments were carried out., Results: Basal values and DPOAE and ABR values on day 7 and 14 of Group 1, Group 2, and Group 3 were similar to each other. No significant difference was detected among the three groups in the histopathological assessment carried out at the end of the study., Conclusion: It was revealed by audiological and histopathological parameters that the use of Mesna at 50% and 100% concentrations did not create toxicity effects on the internal ear. Mesna would be more effective by being used in higher concentrations in audiological surgeries, that its duration of operation world reduce and could being used in different indications including tympanosclerosis., (Copyright © 2018 Elsevier B.V. All rights reserved.)

To evaluate hearing of the contralateral normal ear before and after mastoidectomy in a longitudinal manner and to assess whether the hearing loss is transient or permanent and to find out the duration of temporary hearing loss. This was a clinical longitudinal observational study involving 50 patients with unilateral chronic suppurative otitis media requiring mastoidectomy operation over a period of 18 months after satisfying the inclusion criteria. During the part of the mastoidectomy surgery involving drilling of the mastoid bone, noise levels were recorded at multiple points in the surgery using a digital sound level meter. Postoperatively, beginning from Day 1 to Day 7, PTA and OAE of the contralateral ear were recorded for all patients. The patients were then followed up at 1, 3 and 6 months postoperatively, at which times PTA and OAE were repeated. There is an increase in the absence of High Frequency DPOAEs on the first and second postoperative days, but this increase is higher than that of Low Frequency DPOAEs and gradually returns to normal by 72 h. OAEs were found to be more sensitive at diagnosing and tracking the progress of affected patients. All affected ears only had a temporary postoperative hearing loss, primarily affecting the higher frequencies and returning to normal within 72 h. Drill-generated noise and vibration during mastoidectomy operation is associated with a significant temporary shift in hearing thresholds of the contralateral normal ear in susceptible individuals, affecting the higher frequencies, and is best evaluated using DPOAEs., Competing Interests: Compliance with ethical standardsNone.

The absence of functional outer hair cells is a component of several forms of hereditary hearing impairment, including Usher syndrome, the most common cause of concurrent hearing and vision loss. Antisense oligonucleotide (ASO) treatment of mice with the human Usher mutation, Ush1c c.216G>A, corrects gene expression and significantly improves hearing, as measured by auditory-evoked brainstem responses (ABRs), as well as inner and outer hair cell (IHC and OHC) bundle morphology. However, it is not clear whether the improvement in hearing achieved by ASO treatment involves the functional rescue of outer hair cells. Here, we show that Ush1c c.216AA mice lack OHC function as evidenced by the absence of distortion product otoacoustic emissions (DPOAEs) in response to low-, mid-, and high-frequency tone pairs. This OHC deficit is rescued by treatment with an ASO that corrects expression of Ush1c c.216G>A. Interestingly, although rescue of inner hairs cells, as measured by ABR, is achieved by ASO treatment as late as 7 days after birth, rescue of outer hair cells, measured by DPOAE, requires treatment before post-natal day 5. These results suggest that ASO-mediated rescue of both IHC and OHC function is age dependent and that the treatment window is different for the different cell types. The timing of treatment for congenital hearing disorders is of critical importance for the development of drugs such ASO-29 for hearing rescue.

Neuroglobin (Ngb) is a member of the globin family of respiratory proteins, which was recently observed in many neurons of the auditory pathways. Up to now, however, nothing was known about the role of Ngb in hearing processes. We therefore studied auditory function by recording distortion-product otoacoustic emissions (DPOAE) and auditory brainstem responses (ABRs) in wild-type (C57BL/6N) and Ngb-knockout mice. In KO mice, DPOAE thresholds were moderately augmented in the range of 5-18 kHz, reaching statistical significance at 8 and 10 kHz, while the ABR thresholds were not different between groups. The activation of the efferent system by an additional noise given to the contralateral ear resulted in an increased f2-f1-emission level only in WT animals. A noise exposure resulted in similar acute threshold shifts in the DPOAE and ABR of both animal groups. The recovery of hearing function, expressed by decreased DPOAE thresholds, was not significantly different between groups after four days and after four weeks. ABR recordings showed that threshold shifts elicited by noise-trauma were slightly better revised in wild-type mice. While ABR amplitudes were similar in both groups before noise overexposure, four weeks after trauma a moderate but statistically significant decrease of the latest peak-to-peak response amplitude (originating in the inferior colliculus) was observed in KO mice. Our results suggest that the lack of Ngb, at least in the model used in the present study, results in only marginal deficits in hearing ability. A putative functional role of Ngb in the efferent system warrants further studies., (Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.)

Mutations of Connexin 26 (Cx26, GJB2), which is a predominant gap junction isoform in the cochlea, can induce high incidence of nonsyndromic hearing loss. We previously found that targeted-deletion of Cx26 in supporting Deiters cells and outer pillar cells in the cochlea can influence outer hair cell (OHC) electromotility and reduce active cochlear amplification leading to hearing loss, even though there are no gap junction connexin expressions in the auditory sensory hair cells. Here, we further report that hearing loss and the reduction of active amplification in the Cx26 targeted-deletion mice are progressive and different at high and low frequency regions, first occurring in the high frequency region and then progressively extending to the middle and low frequency regions with mouse age increased. The speed of hearing loss extending was fast in the basal high frequency region and slow in the apical low frequency region, showing a logarithmic function with mouse age. Before postnatal day 25, there were no significant hearing loss and the reduction of active cochlear amplification in the low frequency region. Hearing loss and the reduction of active cochlear amplification also had frequency difference, severe and large in the high frequency regions. These new data indicate that the effect of gap junction on active cochlear amplification is progressive, but, consistent with our previous report, exists in both high and low frequency regions in adulthood. These new data also suggest that cochlear gap junctions may have an important role in age-related hearing loss., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Conclusion: The ovariectomy in rats does not change their auditory function. However, combining ovariectomy with Cisplatin treatment increases the risk of damaging the auditory function relative to the ototoxic effect caused by Cisplatin alone or ovariectomy alone., Objectives: The auditory benefit from estrogen depends on a number of factors that make findings among studies controversial. The present study was to examine the impact of Cisplatin, a chemotherapy drug, on the auditory function of ovariectomized rats., Methods: Thirty-two female rats were assigned to three groups (OVX + C, OVX - C, Sham + C). The rats in the OVX + C and OVX - C groups received bilateral ovariectomy, and those in the Sham + C group received a sham surgery with intact ovaries. After 6 weeks the rats in the OVX + C and Sham + C groups were then treated with Cisplatin for 4 days, but not those in the OVX - C group (control). The auditory function was measured with DPOAE SNRs and ABR thresholds before the surgery and after the Cisplatin treatment., Results: The OVX + C group had significantly decreased the DPOAE SNRs and increased the ABR thresholds relative to the Sham + C group at stimulus frequencies between 2-8 kHz, and the Sham + C group also had worse auditory function than the OVX - C group.

Conclusion: Low-dose administration of Aspartame (Ap) did not produce a significant ototoxic effect at the end of the 6th month. However, duration of the ototoxic effect is shortened and severity of the effect is increased as dose and duration of Ap administration is increased., Objectives: While Ap toxicity has been studied in short- and long-term studies, its effects on hearing have not been investigated. This study was conducted to evaluate the effects of long-term consumption of Ap administered in various doses on hearing status of rats., Methods: The study included 54 female Wistar Albino rats. Ap was given for 6 months to the rats. The groups were assigned according to levels of Ap dosage. DPOAE and ABR tests were utilized for serial hearing evaluations. Serial hearing measurement times were designed as baseline, 1st week, 2nd week, 1st, 2nd, 3rd, and 6th months., Results: While audiological parameters deteriorated with 100 mg/kg/day dose after the 3rd month, ABR thresholds were elevated and DPOAE values were significantly decreased in 500 mg/kg/day and 1000 mg/kg/day applications after the 2nd month. In 2000 mg/kg/day and 4000 mg/kg/day applications, deteriorations in audiological parameters were detected as early as the first and second months; respectively.

Autism spectrum disorder (ASD) is a behaviorally diagnosed disorder of early onset characterized by impairment in social communication and restricted and repetitive behaviors. Some of the earliest signs of ASD involve auditory processing, and a recent study found that hearing thresholds in children with ASD in the mid-range frequencies were significantly related to receptive and expressive language measures. In addition, otoacoustic emissions have been used to detect reduced cochlear function in the presence of normal audiometric thresholds. We were interested then to know if otoacoustic emissions in children with normal audiometric thresholds would also reveal differences between children with ASD and typical developing (TD) controls in mid-frequency regions. Our objective was to specifically measure baseline afferent otoacoustic emissions (distortion-product otoacoustic emissions [DPOAEs]), transient-evoked otoacoustic emissions (TrOAEs), and efferent suppression, in 35 children with high-functioning ASD compared with 42 aged-matched TD controls. All participants were males 6-17 years old, with normal audiometry, and rigorously characterized via Autism Diagnostic Interview-Revised and Autism Diagnostic Observation Schedule. Children with ASD had greatly reduced DPOAE responses in the 1 kHz frequency range, yet had comparable DPOAE responses at 0.5 and 4-8 kHz regions. Furthermore, analysis of the spectral features of TrOAEs revealed significantly decreased emissions in ASD in similar frequencies. No significant differences were noted in DPOAE or TrOAE noise floors, middle ear muscle reflex activity, or efferent suppression between children with ASD and TD controls. In conclusion, attention to specific-frequency deficits using non-invasive measures of cochlear function may be important in auditory processing impairments found in ASD. Autism Res 2017, 10: 337-345. © 2016 International Society for Autism Research, Wiley Periodicals, Inc., (© 2016 International Society for Autism Research, Wiley Periodicals, Inc.)

Evaluation of cervical evoked myogenic potentials (c-VEMP) is commonly applied in clinical investigations of patients with suspected neurotological symptoms. Short intense acoustic stimulation of peak levels close to 130 dB SPL is required to elicit the responses. A recent publication on bilateral significant sensorineural hearing loss related to extensive VEMP stimulation motivates evaluations of immediate effects on hearing acuity related to the intense acoustic stimulation required to elicit c-VEMP responses. The aim of the current study was to investigate changes in DPOAE-levels and hearing thresholds in relation to c-VEMP testing in humans. More specifically, the current focus is on immediate changes in hearing thresholds and changes in DPOAE-levels at frequencies 0.5 octaves above the acoustic stimulation when applying shorter tone bursts than previously used. Hearing acuity before and immediately after exposure to c-VEMP stimulation was examined in 24 patients with normal hearing referred for neurotologic testing. The stimulation consisted of 192 tonebursts of 6 ms and was presented at 500 Hz and 130 dB peSPL. Békésy thresholds at 0.125-8 kHz and DPOAE I/O growth functions with stimulation at 0.75 and 3 kHz were used to assess c-VEMP related changes in hearing status. No significant deterioration in Békésy thresholds was detected. Significant reduction in DPOAE levels at 0.75 (0.5-1.35 dB) and 3 kHz (1.6-2.1 dB) was observed after c-VEMP stimulation without concomitant changes in cochlear compression. The results indicated that there was no immediate audiometric loss related to c-VEMP stimulation in the current group of patients. The significant reduction of DPOAE levels at a wider frequency range than previously described after the c-VEMP test could be related to the stimulation with shorter tone bursts. The results show that c-VEMP stimulation causes reduction in DPOAE-levels at several frequencies that corresponds to half the reductions in DPOAE levels reported after exposure to the maximally allowed occupational noise for an 8 h working day. Consequently, extended stimuli intensity or stimulation repetition with c-VEMP testing should be avoided to reduce the risk for noise-induced cochlear injury., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Introduction  There is only limited information from previous studies that suggest that auditory function may be influenced by hormones. Recent advances in the field have exposed the potential role of hormones in modulating the auditory system. Objective  This study aims to investigate the relationship between menstrual cycle and outer hair cell function with audiological examination. Methods  This is an analytic study with a cross-sectional design. The sampling was a systematic random sampling. We found 49 women with normal menstrual cycle and collected their data through interviews, physical examination, and examination of the ear, with otoscopic and other routine otorhinolaryngology examinations. We evaluated Tympanometry, distortion-product otoacoustic emissions (DPOAE), and pure tone audiometry. Results  We found the audiometric threshold worse in the follicular phase than other phases at 4000 Hz of the right ear, and in the ovulation was found best than any other phases at 1000 Hz of the left ear with significant difference. We found significant difference of DPOAE between ovulation time and follicular phase at 3000 Hz and 1000 Hz in the left ear and between ovulation and luteal phased at 2000 Hz, 3000 Hz and 5000 Hz in the right ear and at 1000 Hz in the left ear with p  < 0.05. Conclusion  The result of this study showed that only a small part of audiometry threshold had a significant difference between each menstrual phase. In other words, we found no correlation between menstrual and audiometry threshold. Nonetheless, there is a correlation between menstrual cycle phase and DPOAE amplitude.

Efferent auditory feedback on cochlear hair cells is well studied regarding olivocochlear brainstem mechanisms. Less is known about how the descending corticofugal system may shape efferent feedback and modulate cochlear mechanics. Distortion-product otoacoustic emissions (DPOAEs) are a suitable tool to assess outer hair cell function, as they are by-products of the nonlinear cochlear amplification process. The present project investigates the effects of cortical activity on cubic and quadratic DPOAEs in mongolian gerbils, Meriones unguiculatus, through cortical deactivation using the sodium-channel blocker lidocaine. Contralateral cortical microinjections of lidocaine can lead to either an increase or decrease of median DPOAE levels of up to 10.95 dB. The effects are reversible and comparable at all tested frequencies (0.5-40 kHz). They are not restricted to the preferred frequency of the cortical site of injection. Recovery times are between 20 and 120 min depending on stimulation levels and emission type. When the injection is performed in the ipsilateral hemisphere, DPOAE level shifts are lower in amplitude compared to those after injection in the contralateral hemisphere. No significant changes in DPOAE levels are obtained after saline microinjections. Results indicate that deactivation of auditory cortex activity through lidocaine has a considerable impact on peripheral auditory responses in form of DPOAEs, probably through cortico-olivocochlear pathways., (Copyright © 2015 Elsevier B.V. All rights reserved.)

In 1996, a new type of bilateral hearing disorder was discerned and published almost simultaneously by Kaga et al. [1] and Starr et al. [2]. Although the pathophysiology of this disorder as reported by each author was essentially identical, Kaga used the term "auditory nerve disease" and Starr used the term "auditory neuropathy". Auditory neuropathy (AN) in adults is an acquired disorder characterized by mild-to-moderate pure-tone hearing loss, poor speech discrimination, and absence of the auditory brainstem response (ABR) all in the presence of normal cochlear outer hair cell function as indicated by normal distortion product otoacoustic emissions (DPOAEs) and evoked summating potentials (SPs) by electrocochleography (ECoG). A variety of processes and etiologies are thought to be involved in its pathophysiology including mutations of the OTOF and/or OPA1 genes. Most of the subsequent reports in the literature discuss the various auditory profiles of patients with AN [3,4] and in this report we present the profiles of an additional 17 cases of adult AN. Cochlear implants are useful for the reacquisition of hearing in adult AN although hearing aids are ineffective. In 2008, the new term of Auditory Neuropathy Spectrum Disorders (ANSD) was proposed by the Colorado Children's Hospital group following a comprehensive study of newborn hearing test results. When ABRs were absent and DPOAEs were present in particular cases during newborn screening they were classified as ANSD. In 2013, our group in the Tokyo Medical Center classified ANSD into three types by following changes in ABRs and DPOAEs over time with development. In Type I, there is normalization of hearing over time, Type II shows a change into profound hearing loss and Type III is true auditory neuropathy (AN). We emphasize that, in adults, ANSD is not the same as AN., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

2,3,7,8-tetrachorodibenzo-p-dioxin (TCDD), a ubiquitous and persistent environmental contaminant, is a potent teratogen. Whereas developmental TCDD toxicity is mediated by the aryl hydrocarbon receptor (AhR), the normal function of the AhR is poorly understood. We tested whether dioxin exposure during a critical period of hair cell development disrupts cochlear function in three mouse strains, (C57BL6, BalbC, and CBA) that contain high affinity AhR-b alleles. C57BL/6, BalbC, and CBA dams were exposed to 500 ng/kg TCDD or olive oil (vehicle) on embryonic day 12 by gavage. Cochlear function was analyzed at 1.5 months of age by measuring 1) auditory brainstem response (ABRs) to tone pips from 5.6 to 30 kHz, and 2) distortion-product otoacoustic emissions (DPOAEs) evoked by primaries with f2 at the same frequency values. Cochlear threshold sensitivity following TCDD exposure was significantly elevated in both female and male mice in the C57BL/6 strain, carrying the Ahb-1 allele, but not significantly elevated in the BalbC or CBA strains, carrying the Ahb-2 allele. These ABR threshold deficits in mice carrying the Ahb-1 allele parallels the cleft palate incidence to higher TCDD exposures, suggesting that ABR testing could serve as a sensitive indicator of TCDD toxicity in at-risk children. Moreover, DPOAEs were not affected following TCDD exposure in any of the mouse strains, suggesting that following TCDD exposure mice with the Ahb-1 allele exhibit a mild auditory neuropathy. The causes of many auditory neuropathies are unknown, yet a developmental exposure to dioxin may be a risk factor for this condition., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Hearing impairment is characterized by two potentially coexisting sensorineural components: (i) cochlear gain loss that yields wider auditory filters, elevated hearing thresholds and compression loss, and (ii) cochlear neuropathy, a noise-induced component of hearing loss that may impact temporal coding fidelity of supra-threshold sound. This study uses a psychoacoustic amplitude modulation (AM) detection task in quiet and multiple noise backgrounds to test whether these aspects of hearing loss can be isolated in listeners with normal to mildly impaired hearing ability. Psychoacoustic results were compared to distortion-product otoacoustic emission (DPOAE) thresholds and envelope-following response (EFR) measures. AM thresholds to pure-tone carriers (4 kHz) in normal-hearing listeners depended on temporal coding fidelity. AM thresholds in hearing-impaired listeners were normal, indicating that reduced cochlear gain may counteract how reduced temporal coding fidelity degrades AM thresholds. The amount with which a 1-octave wide masking noise worsened AM detection was inversely correlated to DPOAE thresholds. The narrowband noise masker was shown to impact the hearing-impaired listeners more so than the normal hearing listeners, suggesting that this masker may be targeting a temporal coding deficit. This study offers a window into how psychoacoustic difference measures can be adopted in the differential diagnostics of hearing deficits in listeners with mixed forms of sensorineural hearing loss.

Objectives: Hearing loss in neonatal intensive care unit (NICU) graduates range from 2% to 15% compared to 0.3% in full-term births, and the etiology of this discrepancy remains unknown. The majority of NICU admissions receive potentially ototoxic aminoglycoside therapy, such as gentamicin, for presumed sepsis. Endotoxemia and inflammation are associated with increased cochlear uptake of aminoglycosides and potentiated ototoxicity in mice. We tested the hypothesis that sepsis or systemic inflammatory response syndrome (SIRS) and intravenous gentamicin exposure increases the risk of hearing loss in NICU admissions., Methods: The Institutional Review Board at Oregon Health & Science University (OHSU) approved this study design. Two hundred and eight infants met initial criteria, and written, informed consent were obtained from parents or guardians of 103 subjects ultimately enrolled in this study. Prospective data from 91 of the enrolled subjects at OHSU Doernbecher Children's Hospital Neonatal Care Center were processed. Distortion product otoacoustic emissions (DPOAEs; f2 frequency range: 2063-10,031 Hz) were obtained prior to discharge to assess auditory performance. To pass the DPOAE screen, normal responses in >6 of 10 frequencies in both ears were required; otherwise the subject was considered a "referral" for a diagnostic hearing evaluation after discharge. Cumulative dosing data and diagnosis of neonatal sepsis or SIRS were obtained from OHSU's electronic health record system, and the data processed to obtain risk ratios., Results: Using these DPOAE screening criteria, 36 (39.5%) subjects would be referred. Seventy-four (81%) subjects had intravenous gentamicin exposure. Twenty (22%) had ≥4 days of gentamicin, and 71 (78%) had <4 days. The risk ratio (RR) of referral with ≥4 days of gentamicin was 1.92 (p=0.01). Eighteen subjects had sepsis or met neonatal SIRS criteria, 9 of whom had ≥5 days of gentamicin and a DPOAE referral risk ratio of 2.12 (p=0.02) compared to all other subjects. Combining subjects with either vancomycin or furosemide overlap with gentamicin treatment yielded an almost significant risk ratio (RR=1.77, p=0.05) compared to the rest of the cohort., Conclusions: We report an increased risk of referral with DPOAE screening for those receiving ≥4 days of intravenous gentamicin administration that may contribute to the greater prevalence of hearing loss in NICU graduates. We propose an expanded prospective study to gather a larger cohort of subjects, identifying those with sepsis or neonatal SIRS, to increase the statistical power of this study design. Subsequent studies also need to obtain follow-up diagnostic audiological data to verify whether the outcomes of DPOAE screening, in addition to the standard AABR screen, is a reliable predictor of permanent hearing loss following gentamicin exposure in the NICU., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Distortion product otoacoustic emissions (DPOAE) in newborns and adults were evoked by sweeping primaries up and down in frequency at 1 s/octave. Sweeping up and down in frequency resulted in changes in the amplitude vs. frequency functions of the composite DPOAE and its two major components. In addition, DPOAE component phases differed slightly between the up- and down-swept conditions. The changes in amplitude vs. frequency functions were quantified using a covariate correlation technique, yielding single-valued estimates of the magnitude of the frequency changes. Separate analyses were performed for the entire DPOAE frequency range and split into low and high frequency ranges. There were consistent changes in newborn and adult composite DPOAEs and reflection components, but not generator components. Adults had significant frequency changes in the composite DPOAE for all frequency ranges and in the reflection component for the entire frequency range. Newborns had significant frequency change in the reflection component for all frequency ranges. Differences in frequency change between adults and newborns may stem from developmental changes in cochlear processing. Alignment of the component phase differences between the up- and down-swept conditions resulted in elimination of frequency-change in reconstructed composite DPOAEs., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Objective: Betahistine augments cochlear blood flow and is currently used as an efficient therapeutic agent. Amikacin is used in a wide range of areas, but its ototoxic effect continues to be problematic. This study investigates the effect of betahistine on amikacin-induced ototoxicity., Methods: Thirty-two healthy rats were randomized to 4 groups of 8 rats in each group (amikacin, amikacin+betahistine, betahistine, and no treatment). Amikacin was administered intramuscularly to groups 1 and 2 for 14 days. Betahistine was delivered by oral gavage to groups 2 and 3 for 21 days. Distortion-product otoacoustic emissions (DPOAE) and auditory brainstem response (ABR) tests were conducted on all rats., Results: There were significant decreases in the DPOAE levels and significant increases in the ABR thresholds of the amikacin and amikacin+betahistine groups on the 7th, 14th, and 21st days, as compared to their basal values. The DPOAE levels of the amikacin+betahistine group significantly decreased on days 7, 14, and 21, and the ABR thresholds significantly increased on the same days, as compared to the amikacin group., Conclusion: Our study implies that amikacin's ototoxic effects are augmented by the concurrent use of betahistine. Experimental and clinical research, supported by histopathological studies, is needed to affirm our findings., (© The Author(s) 2014.)

Atypical medial olivocochlear (MOC) feedback from brain stem to cochlea has been proposed to play a role in tinnitus, but even well-constructed tests of this idea have yielded inconsistent results. In the present study, it was hypothesized that low sound tolerance (mild to moderate hyperacusis), which can accompany tinnitus or occur on its own, might contribute to the inconsistency. Sound-level tolerance (SLT) was assessed in subjects (all men) with clinically normal or near-normal thresholds to form threshold-, age-, and sex-matched groups: 1) no tinnitus/high SLT, 2) no tinnitus/low SLT, 3) tinnitus/high SLT, and 4) tinnitus/low SLT. MOC function was measured from the ear canal as the change in magnitude of distortion-product otoacoustic emissions (DPOAE) elicited by broadband noise presented to the contralateral ear. The noise reduced DPOAE magnitude in all groups ("contralateral suppression"), but significantly more reduction occurred in groups with tinnitus and/or low SLT, indicating hyperresponsiveness of the MOC system compared with the group with no tinnitus/high SLT. The results suggest hyperresponsiveness of the interneurons of the MOC system residing in the cochlear nucleus and/or MOC neurons themselves. The present data, combined with previous human and animal data, indicate that neural pathways involving every major division of the cochlear nucleus manifest hyperactivity and/or hyperresponsiveness in tinnitus and/or low SLT. The overactivation may develop in each pathway separately. However, a more parsimonious hypothesis is that top-down neuromodulation is the driving force behind ubiquitous overactivation of the auditory brain stem and may correspond to attentional spotlighting on the auditory domain in tinnitus and hyperacusis., (Copyright © 2014 the American Physiological Society.)

Noise produced by magnetic resonance imaging (MRI) scanners (which can peak at a sound pressure level of 131 dB) has been shown to cause noise-induced cochlear dysfunction in people. The aim of this study was to investigate whether noise produced during MRI had a deleterious effect on cochlear function in dogs, using distortion product otoacoustic emission (DPOAE) testing, which allows frequency specific, non-invasive assessment of cochlear function. DPOAE testing was performed before and after MRI in one or both ears under general anaesthesia at 14 frequency pairs (f2 frequency ranging from 0.84 kHz to 8.0 kHz). A control group comprised dogs undergoing anaesthesia of a similar duration for quiet procedures. Thirty-six dogs (66 ears) and 17 dogs (28 ears) were included in the MRI and control groups respectively. There was a reduction in DPOAE at all frequencies tested in the MRI group; a similar effect was not evident in the control group. This reduction in the MRI group was statistically significant in five of the 14 frequencies assessed (P < 0.05). These results demonstrate that exposure to MRI noise results in a significant reduction in frequency-specific cochlear function in dogs, although it is not known whether this is reversible or permanent. This suggests that all dogs undergoing MRI studies should be provided with ear protection as a routine precautionary measure., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Objectives/hypothesis: The purpose of this study is to assess the effect of fractionated radiotherapy on sensorineural hearing loss using an animal model., Study Design: In vivo animal study., Methods: Ears of 25 guinea pigs were divided into three groups: control, irradiated with a total of 48 gray (Gy), and 71 Gy. Unilateral exposure of 48 Gy and 71 Gy fractionated irradiation was given for a 4-week period. Auditory brainstem response and distortion products otoacoustic emissions (DPOAE) were tested prior to irradiation and 1, 6, 10, and 16 weeks after completion of radiotherapy to assess the hearing threshold shift postradiotherapy over time., Results: No significant differences in hearing thresholds between the low dose radiation (48 Gy) and the control group (no radiation) underlined that 48 Gy caused no hearing deficits (P = 0.37). The higher dose (71 Gy) showed progressive deterioration of the hearing function over time. Three-way ANOVA interactions revealed significant group-time effects (F= 9.261; P < 0.0001). DPOAE analysis demonstrated hearing loss at 71 Gy without progression or recovery at all time points, predominantly in the higher frequencies tested., Conclusion: The present study suggests that in the presence of sensorineural hearing loss due to high- dose fractionated radiotherapy, there is an initial sensorial component; however, the neural component is responsible for its progressivity., (© 2014 The American Laryngological, Rhinological and Otological Society, Inc.)

Aims: The role of intracranial hypertension in acute mountain sickness (AMS) is a matter of debate. Distortion product otoacoustic emissions (DPOAEs) can be used to monitor the intracranial pressure (ICP) noninvasively with a level decrease at the frequencies f2=1 and 1.5 kHz indicating elevated ICP., Methods: DPOAEs (f2=1, 1.5, 2, 3, and 4 kHz), oxygen saturation (Sao2) and the Lake Louise score (LLS) to assess AMS were measured in trekking tourists on the Mount Everest trek in Nepal at 2610 m and 5170 m., Results: Paired data of both altitudes could be obtained of 187 subjects. All results are given in mean±SD. Sao2 was 94.8±2.7% at 2610 m and 79.0±6.9% at 5170 m. While at 2610 m, none of the study subjects had AMS (LLS 0.04±0.02), at 5170 m 82 (43.9%) had AMS when defined as LLS>2, and 31 (16.6%) when defined as LLS>4 (LLS 2.8±2.2). DPOAE levels decreased at altitude in all frequencies without a difference between trekkers with AMS and without AMS. Low Sao2 correlated with high LLS. Low Sao2 correlated with larger DPOAE level decrease only at f2=1 kHz, while the other frequencies showed no correlation. DPOAE level decrease and LLS showed no correlation., Conclusions: Our data suggest that subjects with AMS symptoms did not have higher ICP compared to healthy subjects. Consequently, it seems unlikely that intracranial hypertension accounts for the symptoms of AMS.

Attending to a single stimulus in a complex multisensory environment requires the ability to select relevant information while ignoring distracting input. The underlying mechanism and involved neuronal levels of this attentional gain control are still a matter of debate. Here, we investigated the influence of intermodal attention on different levels of auditory processing in humans. It is known that the activity of the cochlear amplifier can be modulated by efferent neurons of the medial olivocochlear complex. We used distortion product otoacoustic emission (DPOAE) measurements to monitor cochlear activity during an intermodal cueing paradigm. Simultaneously, central auditory processing was assessed by electroencephalography (EEG) with a steady-state paradigm targeting early cortical responses and analysis of alpha oscillations reflecting higher cognitive control of attentional modulation. We found effects of selective attention at all measured levels of the auditory processing: DPOAE levels differed significantly between periods of visual and auditory attention, showing a reduction during visual attention, but no change during auditory attention. Primary auditory cortex activity, as measured by the auditory steady-state response (ASSR), differed between conditions, with higher ASSRs during auditory than visual attention. Furthermore, the analysis of cortical oscillatory activity revealed increased alpha power over occipitoparietal and frontal regions during auditory compared with visual attention, putatively reflecting suppression of visual processing. In conclusion, this study showed both enhanced processing of attended acoustic stimuli in early sensory cortex and reduced processing of distracting input, both at higher cortical levels and at the most peripheral level of the hearing system, the cochlea., (Copyright © 2014 the authors 0270-6474/14/349995-08$15.00/0.)

Objective: Aminoglycoside antibiotics are known to have ototoxic effects and may induce sensorineural hearing loss. This study investigated the protective effect of trimetazidine, which has antioxidant and cytoprotective properties, against amikacin ototoxicity., Methods: Thirty-two male rats were divided into four groups - amikacin, amikacin + trimetazidine, trimetazidine, and control groups. Trimetazidine, 10 mg/kg per day, was given for 14 days by oral gavage. Amikacin, 600 mg/kg per day, was also given for 14 days, by the intramuscular route. Distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) tests were applied to the rats for hearing assessment. At the termination of the study, the biochemical parameters were calculated to evaluate the oxidative status., Results: The DPOAE values of the amikacin group were significantly lower on the 7th and 14th days than those of the trimetazidine + amikacin group and there was an increase in the ABR thresholds. The ABR thresholds for the amikacin group on the 7th and 14th days were significantly higher than the levels on the first day of the study, while there was no significant increase in those values in the trimetazidine + amikacin group. The total oxidant status (TOS) and oxidant status index (OSI) values of the amikacin group were significantly higher than those of the trimetazidine + amikacin group. The total antioxidant status (TAS) values of the amikacin group were lower than those of the trimetazidine + amikacin group., Conclusions: The audiologic tests and biochemical parameters investigated in this study both point to the protective effect of trimetazidine against amikacin-induced ototoxicity., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Age-related hearing loss - presbycusis - is the number one communication disorder and most prevalent neurodegenerative condition of our aged population. Although speech understanding in background noise is quite difficult for those with presbycusis, there are currently no biomedical treatments to prevent, delay or reverse this condition. A better understanding of the cochlear mechanisms underlying presbycusis will help lead to future treatments. Objectives of the present study were to investigate GABAA receptor subunit α1, nicotinic acetylcholine (nACh) receptor subunit β2, and N-methyl-d-aspartate (NMDA) receptor subunit NR1 mRNA and protein expression changes in spiral ganglion neurons (SGN) of the CBA/CaJ mouse cochlea, that occur in age-related hearing loss, utilizing quantitative immunohistochemistry and semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) techniques. We found that auditory brainstem response (ABR) thresholds shifted over 40dB from 3 to 48kHz in old mice compared to young adults. DPOAE thresholds also shifted over 40dB from 6 to 49kHz in old mice, and their amplitudes were significantly decreased or absent in the same frequency range. SGN density decreased with age in basal, middle and apical turns, and SGN density of the basal turn declined the most. A positive correlation was observed between SGN density and ABR wave 1amplitude. mRNA and protein expression of GABAAR α1 and AChR β2 decreased with age in SGNs in the old mouse cochlea. mRNA and protein expression of NMDAR NR1 increased with age in SGNs of the old mice. These findings demonstrate that there are functionally-relevant age-related changes of GABAAR, nAChR, NMDAR expression in CBA mouse SGNs reflecting their degeneration, which may be related to functional changes in cochlear synaptic transmission with age, suggesting biological mechanisms for peripheral age-related hearing loss., (Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.)

Prevention and rehabilitation of hearing loss and tinnitus, the two most commonly awarded service-connected disabilities, are high priority initiatives in the Department of Veterans Affairs (VA). At least 4,000 Veterans, most with significant hearing loss, will receive cisplatin this year, with more than half sustaining permanent hearing shift and nearly 40% developing new tinnitus. With improved survivability following cancer treatment, Veterans treated with cisplatin are approached with the dual goals of effective treatment and preserved quality of life. This article describes COMP-VA, a comprehensive ototoxicity monitoring program developed for VA patients receiving cisplatin. The program includes an individualized pretreatment prediction model that identifies the likelihood of hearing shift given cisplatin dose and patient factors. It supports both manual and automated hearing testing with a newly developed portable audiometer capable of performing the recommended procedures on the chemotherapy unit during treatment. It also includes objective methods for identifying outer hair cell changes and predicting audiogram changes using distortion-product otoacoustic emissions. We describe this program of evidence-based ototoxicity monitoring protocols using a case example to give the reader an understanding of how this program would be applied, along with a plan for future work to accomplish the final stages of program development.

The prevalence of hearing problems in the Western world has, due to aging of the population, doubled over the past 30 years. Thereby, noise-induced hearing loss is an important factor that worsens over time in addition to age-related hearing loss. Hearing loss is usually measured as an elevation of a person's hearing thresholds, expressed in decibel (dB). However, recent animal studies have unraveled a type of permanent cochlear damage, without an elevation of hearing thresholds. This subtle damage is linked to a permanent and progressive degeneration of auditory fibers that occurs in association with damage of the inner hair cell synapse. Afferent neuronal degeneration has been suggested to be involved in hyperacusis (over sensitivity to sound) and tinnitus (a phantom sound percept). Hyperacusis and tinnitus are potentially devastating conditions that are still incurable. The main risk factors to develop tinnitus or hyperacusis are hearing loss, social stress and age. Both tinnitus and hyperacusis have been discussed in the context of a pathological increased response gain in subcortical brain regions as a reaction to deprivation of sensory input. Novel studies confirm the involvement of peripheral deafferentation for tinnitus and hyperacusis, but suggest that the disorder results from different brain responses to different degrees of deafferentation: while tinnitus may arise as a failure of the brain to adapt to deprived peripheral input, hyperacusis may result from an 'over-adaptive' increase in response gain. Moreover, moderate and high stress levels at the time of acoustic trauma have been suggested to play a pivotal role in the vulnerability of the cochlea to acoustic damage and therefore for the development of tinnitus and hyperacusis., (Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The mechanical tuning of the ear in the moth Empyreuma pugione was investigated by distortion-product otoacoustic emissions (DPOAE) and laser Doppler vibrometry (LDV). DPOAE audiograms were assessed using a novel protocol that may be advantageous for non-invasive auditory studies in insects. To evoke DPOAE, two-tone stimuli within frequency and level ranges that generated a large matrix of values (960 frequency-level combinations) were used to examine the acoustic space in which the moth tympanum shows its best mechanical and acoustical responses. The DPOAE tuning curve derived from the response matrix resembles that obtained previously by electrophysiology, and is V-shaped and tuned to frequencies between 25 and 45 kHz with low Q10dB values of 1.21±0.26. In addition, while using a comparable stimulation regime, mechanical distortion in the displacement of the moth's tympanal membrane at the stigma was recorded with a laser Doppler vibrometer. The corresponding mechanical vibration audiograms were compared with DPOAE audiograms. Both types of audiograms have comparable shape, but most of the mechanical response fields are shifted towards lower frequencies. We showed for the first time in moths that DPOAE have a pronounced analogy in the vibration of the tympanic membrane where they may originate. Our work supports previous studies that point to the stigma (and the internally associated transduction machinery) as an important place of sound amplification in the moth ear, but also suggests a complex mechanical role for the rest of the transparent zone.

Tympanometry is used in evaluating middle ear functional conditions. Before 6 months of age its results may be misleading. High-frequency studies aim to provide more valid procedures. In this study, 236 healthy newborns (127 male, 109 female; 73 % rural, 27 % urban) with age between 0 and 42 days (mean 27 days) no risk for hearing impairment; were analyzed for DPOAE. 209 babies who passed DPOAE were further analyzed for high-frequency tympanometry using Interacoustic AT235h tympanometer, which was possible for 399 ears. The success rate for HFT was 95.3 %. Descriptive statistics for six parameters TPP, Y 200, Y peak, Y tail, YpC-200 and Ypc-tail were analyzed and compared with previous studies. All the parameters except the Ypc-tail were in the range of previous studies.

Introduction: Otoacoustic emissions are routine diagnostics in hearing examination of newborns. Lack of right responses in DPOAE is an indication to father diagnostic procedures to know the reason and institute treatment., Aim: The aim of this paper is analysis of hearing impairment factors in children which are treated in the audiological out-patients ward., Material and Methods: We analyzed retrospectively 168 consecutive children in which diagnostic of hearing apparatus was perform in the first year of life. Children were divided into three groups: with bilateral lack of otoacoustic emissions in newborn ward, with unilateral lack of otoacoustic emissions in newborn ward and with right responses in otoacoustic emissions but with presence of risk factors of hearing impairment in history., Results: In 36 cases results of screening otoacoustic emissions was wrong. Unilateral disturbance of this examination was observed in 24 cases and bilateral in 12 cases. 132 children have right responses in otoacoustic emissions but risk factors of hearing impairment were present., Conclusions: 1. Immaturity, low birthweight and therapy in intensive care ward are important reasons of disturbance in otoacoustic emissions. 2. Administration of ototoxic medications in pregnancy is the most common risk factor of hearing impairment in children., (Copyright © 2013 Polish Otorhinolaryngology - Head and Neck Surgery Society. Published by Elsevier Urban & Partner Sp. z.o.o. All rights reserved.)

Recent studies lead to the conclusion that focused attention, through the activity of corticofugal and medial olivocochlear (MOC) efferent pathways, modulates activity at the most peripheral aspects of the auditory system within the cochlea. In two experiments, we investigated the effects of different intermodal attention manipulations on the response of outer hair cells (OHCs), and the control exerted by the MOC efferent system. The effect of the MOCs on OHC activity was characterized by measuring the amplitude and rapid adaptation time course of distortion product otoacoustic emissions (DPOAEs). In the first, DPOAE recordings were compared while participants were reading a book and counting the occurrence of the letter "a" (auditory-ignoring) and while counting either short- or long-duration eliciting tones (auditory-attending). In the second, DPOAEs were recorded while subjects watched muted movies with subtitles (auditory-ignoring/visual distraction) and were compared with DPOAEs recorded while subjects counted the same tones (auditory-attending) as in Experiment 1. In both Experiments 1 and 2, the absolute level of the averaged DPOAEs recorded during the auditory-ignoring condition was statistically higher than that recorded in the auditory-attending condition. Efferent-induced rapid adaptation was evident in all DPOAE contours, under all attention conditions, suggesting that two medial efferent processes act independently to determine rapid adaptation, which is unaffected by attention, and the overall DPOAE level, which is significantly affected by changes in the focus of attention.