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Topper, R. P. M., J. Trabucho Alexandre, E. Tuenter, and P. Th Meijer. "A regional ocean circulation model for the mid-Cretaceous North Atlantic Basin: implications for black shale formation." Climate of the Past 7, no. 1 (March 21, 2011): 277–97. http://dx.doi.org/10.5194/cp-7-277-2011.
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Abstract. High concentrations of organic matter accumulated in marine sediments during Oceanic Anoxic Events (OAEs) in the Cretaceous. Model studies examining these events invariably make use of global ocean circulation models. In this study, a regional model for the North Atlantic Basin during OAE2 at the Cenomanian-Turonian boundary has been developed. A first order check of the results has been performed by comparison with the results of a recent global Cenomanian CCSM3 run, from which boundary and initial conditions were obtained. The regional model is able to maintain tracer patterns and to produce velocity patterns similar to the global model. The sensitivity of the basin tracer and circulation patterns to changes in the geometry of the connections with the global ocean is examined with three experiments with different bathymetries near the sponges. Different geometries turn out to have little effect on tracer distribution, but do affect circulation and upwelling patterns. The regional model is also used to test the hypothesis that ocean circulation may have been behind the deposition of black shales during OAEs. Three scenarios are tested which are thought to represent pre-OAE, OAE and post-OAE situations. Model results confirm that Pacific intermediate inflow together with coastal upwelling could have enhanced primary production during OAE2. A low sea level in the pre-OAE scenario could have inhibited large scale black shale formation, as could have the opening of the Equatorial Atlantic Seaway in the post-OAE scenario.
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Topper, R. P. M., J. Trabucho Alexandre, E. Tuenter, and P. Th Meijer. "A regional ocean circulation model for the mid-Cretaceous North Atlantic Basin: implications for black shale formation." Climate of the Past Discussions 6, no. 5 (October 29, 2010): 2371–421. http://dx.doi.org/10.5194/cpd-6-2371-2010.
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Abstract. High concentrations of organic matter accumulated in marine sediments during Oceanic Anoxic Events (OAEs) in the Cretaceous. Model studies examining these events invariably make use of global ocean circulation models. In this study, a regional model for the North Atlantic Basin during OAE2 at the Cenomanian-Turonian boundary is developed. A first order check of the results is performed by comparison with the results of a recent global Cenomanian CCSM3 run from which boundary and initial conditions were obtained. The regional model is able to maintain tracer patterns and to produce velocity patterns similar to the global model. The sensitivity of basin tracer and circulation patterns to changes in the geometry of the connections with the global ocean is examined with three experiments with different bathymetries near the sponges. Different geometries turn out to have little effect on tracer distribution, but do affect circulation and upwelling patterns. The regional model is also used to test the hypothesis that ocean circulation may be behind the deposition of black shales during OAEs. Three scenarios are tested which are thought to represent pre-OAE, OAE and post-OAE situations. Model results confirm that Pacific intermediate inflow together with coastal upwelling can have enhanced primary production during OAE2. A low sea level in the pre-OAE scenario can inhibit large scale black shale formation, as can the opening of the Equatorial Atlantic Seaway in the post-OAE scenario.
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Freymueller, Nicholas A., Jason R. Moore, and Corinne E. Myers. "An analysis of the impacts of Cretaceous oceanic anoxic events on global molluscan diversity dynamics." Paleobiology 45, no. 02 (April 10, 2019): 280–95. http://dx.doi.org/10.1017/pab.2019.10.
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AbstractOceanic anoxic events (OAEs) are contemporaneous with 11 of the 18 largest Phanerozoic extinction events, but the magnitude and selectivity of their paleoecological impact remains disputed. OAEs are associated with abrupt, rapid warming and increased CO2flux to the atmosphere; thus, insights from this study may clarify the impact of current anthropogenic climate change on the biosphere. We investigated the influence of the Late Cretaceous Bonarelli event (OAE2; Cenomanian/Turonian stage boundary; ~94 Ma) on generic- and species-level molluscan diversity, extinction rates, and ecological turnover. Cenomanian/Turonian results were compared with changes across all Cretaceous stage boundaries, some of which are coincident with less severe OAEs. We found increased generic turnover, but not species-level turnover, associated with several Cretaceous OAEs. The absence of a species-level pattern may reflect species occurrence data that are too temporally coarse to robustly detect patterns. Five hypotheses of ecological selectivity relating anoxia to survivorship were tested across stage boundaries with respect to faunality, mobility, and diet using generalized linear models. Interestingly, benthic taxa were consistently selected against throughout the Cretaceous regardless of the presence or absence of OAEs. These results suggest that: (1) the Cenomanian/Turonian boundary (OAE2) was associated with a decline in molluscan diversity and increase in extinction rate that were significantly more severe than Cretaceous background levels; and (2) no differential ecological selectivity was associated with OAE-related diversity declines among the variables tested here.
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Aradhana, Aparna, Gadadhar Sarangi, Prasant Saboth, and Radha Tripathy. "Assessment of Hearing Impairment in NICU Graduates by Otoacoustic Emission and Brainstem Evoked Response Audiometry Tests." Journal of Neonatology 34, no. 3 (September 2020): 109–17. http://dx.doi.org/10.1177/0973217920951878.
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Objectives: To find out the incidence of hearing impairment in Neonatal Intensive Care Unit (NICU)-admitted newborns and to correlate between several risk factors. Design: Prospective observational study. Setting: In a tertiary teaching hospital of Odisha between October 2014 and October 2016. Study population: 100 newborns delivered in the institution and admitted in NICU with usual indications and risk factors that underwent otoacoustic emission 1 and 2 (OAE1, OAE2) and Brainstem Evoked Response Audiometry (BERA). Results: 84 babies in OAE1 and 86 babies in OAE2 got “pass” results. In BERA test, 92 babies got normal waveform. 7 (13.7%) of 51 premature babies, 5 (38.5%) of 13 very low birth weight babies, 7 (17.5%) of 40 babies receiving ototoxic medication for >5 days, 7 (31.8%) of 22 babies with hyperbilirubinemia, 6 (42.9%) of 14 babies with sepsis, 5 (20%) of 20 babies with birth asphyxia, 3 (60%) of 5 babies under mechanical ventilation for >5 days, 1 baby with ear abnormality, and 1 (50%) out of 2 babies with congenital infections had hearing impairment and statistically significant association with abnormal OAE and BERA test. Conclusion: There is high incidence of hearing loss in NICU-admitted newborns. OAE and BERA both should be performed for complete evaluation of hearing. Important risk factors are elaborated. Predischarge hearing assessment in NICU is most important.
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Karakitsios, V., H. Tsikos, K. Agiadi - Katsiaouni, S. Dermitzoglou, and E. Chatziharalambous. "THE USE OF CARBON AND OXYGEN STABLE ISOTOPES IN THE STUDY OF GLOBAL PALAEOCEANOGRAPHIC CHANGES: EXAMPLES FROM THE CRETACEOUS SEDIMENT ROCKS OF WESTERN GREECE." Bulletin of the Geological Society of Greece 39, no. 1 (September 10, 2006): 64. http://dx.doi.org/10.12681/bgsg.18445.
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In the present paper we examine the use of carbon and oxygen stable isotopes in the study of global palaeoceanographic changes, with special reference to the oceanic anoxic events (OAEs). The analysis of stable isotopes was applied to the examination of Cretaceous sediments from the Ionian and Pindos zones of Western Greece. In the Ionian zone the carbon and oxygen stable isotopes, combined with biostratigraphic data, record the palaeoenvironmental change corresponding to the anoxic events Bonarelli (Cenomanian/Turonian, OAE2) and Paquier (Lower Albian, OAE1b). In the Pindos zone, within the Cretaceous sediments, we observed two organic-carbon-rich levels. According to the biostratigraphic and isotopie analysis, the first level corresponds to an OAE of Santonian age. This local oceanic anoxic event is described for the first time. The second level, Aptian - Albian age, possibly correlates to either the Paquier event (OAE 1b) or the Selli event (OAE 1a), which in Greece were until now known only in the Ionian zone.
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Machado, M. C., F. Chemale, K. Kawashita, O. Rey, and C. A. V. Moura. "Isotope studies of carbonate rocks of La Luna Formation (Venezuela) to constrain the oceanic anoxic event 3 (OAE3)." Journal of South American Earth Sciences 72 (December 2016): 38–48. http://dx.doi.org/10.1016/j.jsames.2016.07.001.
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Lowery, Christopher M., R. Mark Leckie, and Bradley B. Sageman. "Micropaleontological evidence for redox changes in the OAE3 interval of the US Western Interior: Global vs. local processes." Cretaceous Research 69 (January 2017): 34–48. http://dx.doi.org/10.1016/j.cretres.2016.08.011.
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Mishra, Srikanta K., and Michelle Hernandez. "Temporal Features of Otoacoustic Emissions." Perspectives of the ASHA Special Interest Groups 2, no. 2 (January 2017): 169–75. http://dx.doi.org/10.1044/persp2.sig2.169.
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The true power of otoacoustic emissions (OAEs) continues to be explored. OAE spectral characteristics are typically studied in research and applied in the clinic. However, OAE temporal aspects are relatively underexplored. Not using temporal features is similar to ignoring nearly half of the information that OAEs provide. Besides providing information related to the generation of OAEs and cochlear mechanics, the temporal characteristics have important clinical implications, such as for assessing frequency selectivity, characterizing the strength of the efferent auditory system. This review provides a general synopsis of the fundamental principles of OAE delay and latency and discusses some of the relevant applications in probing the strength of the efferent neural pathway and frequency selectivity. It is expected that the reader will gain an overview of the implications of the latency or phase behavior of OAEs.
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Beil, Sebastian, Wolfgang Kuhnt, Ann Holbourn, Florian Scholz, Julian Oxmann, Klaus Wallmann, Janne Lorenzen, Mohamed Aquit, and El Hassane Chellai. "Cretaceous oceanic anoxic events prolonged by phosphorus cycle feedbacks." Climate of the Past 16, no. 2 (April 29, 2020): 757–82. http://dx.doi.org/10.5194/cp-16-757-2020.
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Abstract. Oceanic anoxic events (OAEs) document major perturbations of the global carbon cycle with repercussions for the Earth's climate and ocean circulation that are relevant to understanding future climate trends. Here, we compare the onset and development of Cretaceous OAE1a and OAE2 in two drill cores with unusually high sedimentation rates from the Vocontian Basin (southern France) and Tarfaya Basin (southern Morocco). OAE1a and OAE2 exhibit remarkable similarities in the evolution of their carbon isotope (δ13C) records, with long-lasting negative excursions preceding the onset of the main positive excursions, supporting the view that both OAEs were triggered by massive emissions of volcanic CO2 into the atmosphere. However, there are substantial differences, notably in the durations of individual phases within the δ13C positive excursions of both OAEs. Based on analysis of cyclic sediment variations, we estimate the duration of individual phases within OAE1a and OAE2. We identify (1) a precursor phase (negative excursion) lasting ∼430 kyr for OAE1a and ∼130 kyr for OAE2, (2) an onset phase of ∼390 and ∼70 kyr, (3) a peak phase of ∼600 and ∼90 kyr, (4) a plateau phase of ∼1340 and ∼200 kyr, and (5) a recovery phase of ∼380 and ∼440 kyr. The total duration of the positive δ13C excursion is estimated at 2700 kyr for OAE1a and 790 kyr for OAE2, and that of the main carbon accumulation phase is estimated at 980 and 180 kyr. The long-lasting peak, plateau and recovery phases imply fundamental changes in global nutrient cycles either (1) by submarine basalt–seawater interactions, (2) through excess nutrient inputs to the oceans by increasing continental weathering and river discharge, or (3) through nutrient recycling from the marine sediment reservoir. We investigated the role of phosphorus in the development of carbon accumulation by analysing phosphorus speciation across OAE2 and the mid-Cenomanian Event (MCE) in the Tarfaya Basin. The ratios of organic carbon and total nitrogen to reactive phosphorus (Corg∕Preact and Ntotal∕Preact) prior to OAE2 and the MCE hover close to or below the Redfield ratio characteristic of marine organic matter. Decreases in reactive phosphorus resulting in Corg∕Preact and Ntotal∕Preact above the Redfield ratio during the later phase of OAE2 and the MCE indicate leakage from the sedimentary column into the water column under the influence of intensified and expanded oxygen minimum zones. These results suggest that a positive feedback loop, rooted in the benthic phosphorus cycle, contributed to increased marine productivity and carbon burial over an extended period of time during OAEs.
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Siedlecki, Tomasz, and Jakub Zielinski. "SPECTRAL KURTOSIS OF OTOACOUSTIC EMISSIONS USING THE HUSIMI TRANSFORM: A PILOT STUDY." Journal of Hearing Science 5, no. 4 (December 31, 2015): 15–25. http://dx.doi.org/10.17430/896155.
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BackgroundTime-frequency distributions can help reveal resonant modes of OAEs. The Husimi transform is the time-frequency distribution of probability. The sound pressure probability density function for a given frequency can be derived from the Husimi transform. Using the Husimi transform as the weight function, it is possible to define the spectral kurtosis of OAEs.Material and MethodsThe Husimi transform was calculated numerically from OAE data recorded from subjects with normal hearing. We examined click-evoked OAEs (CEOAEs) and tone-burst-evoked OAEs (TBOAEs) with stimuli centered at 1, 2, and 4 kHz, and the presence of spontaneous OAEs (SOAEs) was also investigated. The aim of this study was to examine the statistical properties of otoacoustic emissions (OAEs) and relate them to resonant modes of the cochlea. Assuming that the probability of the sound pressure of an OAE at any time and frequency is given by a Husimi-type transform, we analyzed statistical features of the probability distribution, particularly spectral kurtosis.ResultsWith evoked OAEs, a minimum in kurtosis was found at frequencies close to SOAEs. With TBOAEs, three sorts of SOAEs were found: those with high positive kurtosis, those with small positive kurtosis, and those with negative kurtosis; in these cases, SOAEs appeared at the same frequency as the kurtosis minimum.ConclusionsThe kurtosis of evoked components of an OAE is strongly affected by the presence of an SOAE. The number of positive peaks and negative troughs of spectral kurtosis in a given frequency band seem to be characteristic of each subject. It is suggested that a new way of distinguishing types of OAEs may involve calculating the spectral kurtosis, and this may be diagnostically useful.
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Rey, O., J. A. Simo (Toni), and M. A. Lorente. "A record of long- and short-term environmental and climatic change during OAE3: La Luna Formation, Late Cretaceous (Santonian–early Campanian), Venezuela." Sedimentary Geology 170, no. 1-2 (August 2004): 85–105. http://dx.doi.org/10.1016/j.sedgeo.2004.06.006.
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Venancio, Igor M., Thiago P. Santos, Fellippe R. A. Bione, Andre L. Belem, Marcelo C. Bernardes, Rut A. Díaz, Manuel Moreira, et al. "Preservation Factors during Cretaceous Oceanic Anoxic Events in the Espírito Santo Basin, Southeast Brazil." Geosciences 12, no. 10 (September 20, 2022): 351. http://dx.doi.org/10.3390/geosciences12100351.
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The oceanic anoxic events (OAEs) are characterized by enhanced accumulation of organic matter in marine sediments. However, there is still an ongoing debate regarding the interplay between production and preservation during these events. Moreover, few studies provide quantitative estimations of primary productivity and/or the amount of carbon preserved during the OAEs. Here, we used geochemical data from multiple wells located at the Espírito Santo Basin that cover the intervals of events OAE1d and OAE2 to provide quantitative estimates of preservation factors. Our results show enhanced preservation during OAEs compared to modern conditions and a stronger preservation during OAE1d compared to OAE2 in the Espírito Santo Basin. The amount of preserved carbon could reach up to 8.6% during OAE1d, depending on the productivity of the system. In addition, we show that such improvement in preservation is linked to the bottom water with low-O2 concentrations and not due to fast burial caused by high sedimentation rates. Our findings are extremally relevant for organic carbon and source rock modelling studies since model simulations need quantitative estimations.
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Bower, Charles M., and Patti F. Martin. "Universal Pediatric Hearing Screening." Otolaryngology–Head and Neck Surgery 112, no. 5 (May 1995): P149. http://dx.doi.org/10.1016/s0194-5998(05)80392-4.
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Nadon, Vincent, Annelies Bockstael, Dick Botteldooren, and Jérémie Voix. "Field Monitoring of Otoacoustic Emissions During Noise Exposure: Pilot Study in Controlled Environment." American Journal of Audiology 26, no. 3S (October 12, 2017): 352–68. http://dx.doi.org/10.1044/2017_aja-17-0003.
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Purpose In spite of all the efforts to implement workplace hearing conservation programs, noise-induced hearing loss remains the leading cause of disability for North American workers. Nonetheless, an individual's susceptibility to noise-induced hearing loss can be estimated by monitoring changes in hearing status in relation to the level of ambient noise exposure. The purpose of this study was to validate an approach that could improve workplace hearing conservation practices. The approach was developed using a portable and robust system designed for noisy environments and consisted of taking continuous measurements with high temporal resolution of the health status of the inner ear using otoacoustic emissions (OAEs). Method A pilot study was conducted in a laboratory, exposing human subjects to industrial noise recordings at realistic levels. In parallel, OAEs were measured periodically using the designed OAE system as well as with a commercially available OAE system, used as a reference. Results Variations in OAE levels were analyzed and discussed along with the limitations of the reference and designed systems. Conclusions This study demonstrates that the monitoring of an individual's OAEs could be useful in monitoring temporary changes in hearing status induced by exposure to ambient noise and could be considered as a new tool for effective hearing conservation programs in the workplace.
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Papsin, Emily, Adrienne L. Harrison, Mattia Carraro, and Robert V. Harrison. "Contralateral Ear Occlusion for Improving the Reliability of Otoacoustic Emission Screening Tests." International Journal of Otolaryngology 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/248187.
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Newborn hearing screening is an established healthcare standard in many countries and testing is feasible using otoacoustic emission (OAE) recording. It is well documented that OAEs can be suppressed by acoustic stimulation of the ear contralateral to the test ear. In clinical otoacoustic emission testing carried out in a sound attenuating booth, ambient noise levels are low such that the efferent system is not activated. However in newborn hearing screening, OAEs are often recorded in hospital or clinic environments, where ambient noise levels can be 60–70 dB SPL. Thus, results in the test ear can be influenced by ambient noise stimulating the opposite ear. Surprisingly, in hearing screening protocols there are no recommendations for avoiding contralateral suppression, that is, protecting the opposite ear from noise by blocking the ear canal. In the present study we have compared transient evoked and distortion product OAEs measured with and without contralateral ear plugging, in environmental settings with ambient noise levels <25 dB SPL, 45 dB SPL, and 55 dB SPL. We found out that without contralateral ear occlusion, ambient noise levels above 55 dB SPL can significantly attenuate OAE signals. We strongly suggest contralateral ear occlusion in OAE based hearing screening in noisy environments.
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Bergevin, Christopher, Geoffrey A. Manley, and Christine Köppl. "Salient features of otoacoustic emissions are common across tetrapod groups and suggest shared properties of generation mechanisms." Proceedings of the National Academy of Sciences 112, no. 11 (March 3, 2015): 3362–67. http://dx.doi.org/10.1073/pnas.1418569112.
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Otoacoustic emissions (OAEs) are faint sounds generated by healthy inner ears that provide a window into the study of auditory mechanics. All vertebrate classes exhibit OAEs to varying degrees, yet the biophysical origins are still not well understood. Here, we analyzed both spontaneous (SOAE) and stimulus-frequency (SFOAE) otoacoustic emissions from a bird (barn owl, Tyto alba) and a lizard (green anole, Anolis carolinensis). These species possess highly disparate macromorphologies of the inner ear relative to each other and to mammals, thereby allowing for novel insights into the biomechanical mechanisms underlying OAE generation. All ears exhibited robust OAE activity, and our chief observation was that SFOAE phase accumulation between adjacent SOAE peak frequencies clustered about an integral number of cycles. Being highly similar to published results from human ears, we argue that these data indicate a common underlying generator mechanism of OAEs across all vertebrates, despite the absence of morphological features thought essential to mammalian cochlear mechanics. We suggest that otoacoustic emissions originate from phase coherence in a system of coupled oscillators, which is consistent with the notion of “coherent reflection” but does not explicitly require a mammalian-type traveling wave. Furthermore, comparison between SFOAE delays and auditory nerve fiber responses for the barn owl strengthens the notion that most OAE delay can be attributed to tuning.
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Nicholas, Sarah, Joseph Kei, Gail Woodyatt, and Bradley McPherson. "Otoacoustic Emission Findings in Rett Syndrome." Journal of the American Academy of Audiology 10, no. 08 (September 1999): 436–44. http://dx.doi.org/10.1055/s-0042-1748517.
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AbstractRett syndrome is a neurologic disorder affecting mainly females after a seemingly normal 6 to 18 months of life. The resulting developmental disabilities include apparent dementia and loss of acquired language, social skills, and purposeful hand use. The present investigation assessed 10 individuals with Rett syndrome and a control group matched for age and sex. The present study aimed to determine the clinical feasibility of obtaining otoacoustic emissions (OAEs) from the Rett syndrome group and to compare the characteristics of the transient evoked and distortion-product OAEs obtained from the two subject groups. Results indicated that OAE evaluation is a clinically feasible method of assessing individuals with Rett syndrome. The Rett syndrome group had less robust OAEs, especially in the higher frequencies, when compared to the control group. Seven of the Rett syndrome group were identified as having reduced or absent OAEs in at least one ear. These findings suggest a need for hearing screening at an early age and monitoring of hearing on a regular basis. Abbreviations: ABR = auditory brainstem response, DPOAEs = distortion-product otoacoustic emissions, LVR = late vertex response, MLR = middle latency response, OAE = otoacoustic emission, SNR = signal-to-noise ratio, TEOAEs = transient evoked otoacoustic emissions, VRA = visual reinforcement audiometry, WWR = whole-wave reproducibility
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Sachse, V. F., S. Heim, H. Jabour, O. Kluth, T. Schümann, M. Aquit, and R. Littke. "Organic geochemical characterization of Santonian to Early Campanian organic matter-rich marls (Sondage No. 1 cores) as related to OAE3 from the Tarfaya Basin, Morocco." Marine and Petroleum Geology 56 (September 2014): 290–304. http://dx.doi.org/10.1016/j.marpetgeo.2014.02.004.
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Baldwin, Stacey M., Byron J. Gajewski, and Judith E. Widen. "An Evaluation of the Cross-Check Principle Using Visual Reinforcement Audiometry, Otoacoustic Emissions, and Tympanometry." Journal of the American Academy of Audiology 21, no. 03 (March 2010): 187–96. http://dx.doi.org/10.3766/jaaa.21.3.7.
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Background: Early intervention to reduce the effects of congenital hearing loss requires accurate description of hearing loss. In pediatric audiology, a cross-check principle is used to compare behavioral and physiological tests. Purpose: The purpose of this study was to investigate the correspondence of visual reinforcement audiometry (VRA) minimal response levels (MRLs), otoacoustic emissions (OAEs), tympanometry, and VRA test reliability to determine the odds of obtaining the expected cross-check results. We hypothesized that (1) when MRLs were within normal limits (WNL), OAEs would be present; (2) in the event of normal MRLs and absent OAEs, tympanograms would be abnormal; and (3) in the event of elevated MRLs and present OAEs, the tester's confidence in the MRLs would be judged to be only fair, rather than good. Research Design: This was a retrospective study. Study Sample: A previous study provided data from 993 infants who had diagnostic audiologic evaluations at 8–12 mo of age. Data Collection and Analysis: The data were analyzed to compare VRA MRLs with OAE signal-to-noise ratios at 1, 2, and 4 kHz. Odds ratios and 95% confidence intervals were calculated to test the three hypotheses related to the correspondence among MRLs, OAEs, tympanometry, and the reliability of MRLs. Results: The probability that OAEs would be present when MRLs were WNL varied from 12 to 26 to 1, depending on the test frequency. When OAEs were absent in the presence of normal MRLs, the odds of abnormal tympanometry varied from 5 to 10 to 1, depending on the test frequency. When MRLs were elevated (>20 dB HL), the odds suggested that examiners judged the MRLs at 1 and 2 kHz to lack reliability. Conclusion: The results suggest that the cross-check principle is effective when employing VRA, OAE, and tympanometry to rule out or determine the degree, type, and configuration of hearing loss in infants.
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Crouwel, Femke, M. Meurs-Szojda, M. Klemt-Kropp, P. Fockens, and M. Grasman. "The diagnostic yield of open-access endoscopy of the upper gastrointestinal tract in the Netherlands." Endoscopy International Open 06, no. 04 (March 29, 2018): E383—E394. http://dx.doi.org/10.1055/s-0043-123185.
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Abstract Background and study aims Since the introduction of open-access esophago-gastroduodenoscopy (OAE) there is an increase in the total number of performed OAEs whilst the frequency of clinical relevant findings has decreased. The aim of this study was to assess the appropriate use and the diagnostic yield of OAE in the Netherlands and to determine which patient variables are able to predict a malignant finding. Patients and methods A retrospective chart review of all referrals for diagnostic OAE between October 2012 and October 2016 at the Northwest Clinics was performed. The indications were recorded from the referral letter and were classified as “appropriate” or “inappropriate” according to the NHG guideline. Logistic regression was used to detect significant predictive variables for a malignancy. Results A total of 2006 patients were included, of whom 59.6 % had an ‘appropriate’ referral indication. The diagnostic yield of finding a clinical relevant finding was significantly higher for OAEs with an “appropriate” referral indication. Independent risk factors for malignancy were alarm symptoms, age and male gender with a combined AUC of 0.868. Conclusions Only 3.8 % of the malignancies would be missed by strict adherence to the guideline. This indicates that the open-access system in the Netherlands works well. Further improvement of the system can be achieved by only accepting appropriate indications for OAE and by treating patients under the age of 40 without OAE. We showed that a risk-prediction model based on the variables age, alarm symptoms and male gender is a good predictor of malignant finding.
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Gorga, Michael P., Kimberly Preissler, Jeff Simmons, Lisa Walker, and Brenda Hoover. "Some Issues Relevant to Establishing a Universal Newborn Hearing Screening Program." Journal of the American Academy of Audiology 12, no. 02 (February 2001): 101–12. http://dx.doi.org/10.1055/s-0042-1745585.
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AbstractThis article describes some of the factors relevant to the establishment of a universal newborn hearing screening (UNHS) program. First, the difficulty in providing precise estimates of test sensitivity and specificity are reviewed. This section is followed by hypothetical estimates of overall programmatic costs, first for a fixed number of babies to be screened and then as a function of the number of babies to be screened in a year. Included in these estimates are the costs for equipment, disposables, personnel, and follow-up testing. These estimates are provided for three different screening protocols: auditory brainstem response (ABR) alone, otoacoustic emission (OAE) alone, and OAE followed by ABR only for those babies who failed the OAE screening. If follow-up costs are not included, it is less expensive to screen newborns with OAEs compared with the other two protocols. However, once follow-up testing is included as part of the program costs and there are at least 400 births per year, procedures in which OAEs are performed first, followed by an ABR on those infants who do not pass the OAE test, result in the lowest costs. Hospitals with as few as 400 births per year should expect per-baby costs not exceeding $30, regardless of which protocol is used. For all three protocols, the unit costs decrease as the number of babies screened increases. The final section describes data from a local UNHS program in which all infants are screened first with an OAE test, followed by an ABR test on infants not passing the OAE screening. Idiosyncratic features to this program are described, including the fact that all screening tests are performed by audiologists, who are paid on a part-time basis, adding cost to the program. Even under these circumstances, the unit cost is under $30. These data lead us to conclude that all infants can be screened in a cost-effective manner. Abbreviations: ABR = auditory brainstem response, DPOAE = distortion product otoacoustic emission, NICU = neonatal intensive care unit, OAE = otoacoustic emission, UNHS = universal newborn hearing screening
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Prauss, M. L. "Marine palynology of the Oceanic Anoxic Event 3 (OAE3, Coniacian – Santonian) at Tarfaya, Morocco, NW Africa – transition from preservation to production controlled accumulation of marine organic carbon." Cretaceous Research 53 (March 2015): 19–37. http://dx.doi.org/10.1016/j.cretres.2014.10.005.
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S., Gangadhara K., Amrutha V. Bhat, and Sridhara S. "Application of otoacoustic emissions and brainstem evoked response audiometry in newborn hearing screening." International Journal of Otorhinolaryngology and Head and Neck Surgery 8, no. 1 (December 23, 2021): 26. http://dx.doi.org/10.18203/issn.2454-5929.ijohns20214895.
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<p class="abstract"><strong>Background: </strong>Newborn hearing screening was conducted in a tertiary care hospital in a step by step manner using otoacoustic emissions (OAE) and brainstem evoked response audiometry (BERA) and details were recorded.</p><p class="abstract"><strong>Methods:</strong> A prospective institutional based study was conducted. All the newborns born in the hospital over a period of 18 months from December 2018 to May 2020 were considered in the study. Healthy newborns were screened bedside within 24 hours of delivery and NICU (Neonatal Intensive Care Unit) babies were screened in the NICU. Handheld OAE apparatus was used as the initial screening tool. A total of 3 OAEs were done for babies with a “refer” result in the OAEs, which were done 1 month apart. Babies with a “refer” in the third OAE were subjected for BERA.</p><p class="abstract"><strong>Results:</strong> A total of 14226 babies were screened at 24-48 hours of birth. Among them, 13,069 babies passed the first OAE screening in both ears. Remaining babies were referred for further follow-up. After subsequent follow-ups and successive testing, 11 babies were found to have hearing loss, which was diagnosed within 4-5 months of the child’s birth.</p><p class="abstract"><strong>Conclusions: </strong>Universal newborn hearing screening is the need of the day. OAE is an effective screening tool for newborn hearing loss. When complemented by BERA, majority of congenitally deaf babies can be diagnosed at a very early age. This helps in early intervention.</p>
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Hall, James W., Jane E. Baer, Patricia A. Chase, and Mitchell K. Schwaber. "Clinical Application of Otoacoustic Emissions: What do we Know about Factors Influencing Measurement and Analysis?" Otolaryngology–Head and Neck Surgery 110, no. 1 (January 1994): 22–38. http://dx.doi.org/10.1177/019459989411000103.
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Three electrophysiologic audiologic procedures-aural immittance measurement, auditory brainstem response (ABR), and otoacoustic emissions (OAE) — were first described in the 1970's. Immittance measurement and ABR have contributed importantly for years to the assessment of auditory function in children and adults, whereas OAEs have not yet been incorporated into the everyday audiology test battery. In this article, we argue that the transition from OAE measurement by hearing scientists in laboratory settings to routine application by audiologists in the clinic will be greatly facilitated by (1) comprehensive, large-scale studies of the effects of subject characteristics, such as gender and age (from infancy to advancing adulthood), on both transient evoked (TEOAE) and distortion product (DPOAE) otoacoustic emissions; (2) clinical investigations of TEOAE and DPOAE in sizeable patient populations with specific neurotologic diagnoses; (3) guidelines for OAE test protocols in clinical environments; and (4) clear criteria for OAE analysis in clinical populations.
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Jedrzejczak, W. Wiktor, Elżbieta Gos, Edyta Pilka, Piotr H. Skarzynski, Henryk Skarzynski, and Stavros Hatzopoulos. "Pitfalls in the Detection of Hearing Loss via Otoacoustic Emissions." Applied Sciences 11, no. 5 (March 2, 2021): 2184. http://dx.doi.org/10.3390/app11052184.
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Otoacoustic emissions (OAEs) are currently used as a valuable audiological test or as a hearing screening tool. There are many commercially available OAE recording systems that are used both for clinical practice and for research. However, there is little information in the literature comparing their performance in detecting hearing loss. The purpose of this prospective, nonrandomized, and controlled study was to evaluate the screening performance obtained from recent and older versions of the Otometrics Accuscreen OAE screening device in comparison with the Otodynamics ILO-292 OAE system, which has been used as the gold standard. Testing included otoscopic assessment, pure tone audiometry, tympanometry, and transiently evoked OAE (TEOAE) recordings. There was about a 77% agreement between the two versions of the Accuscreen device. Agreement between the two Accuscreen devices and the ILO was approximately 70% for the old and 80% for the new. The newer version of Accuscreen seems to perform better than the old, being more consistent with the reference ILO system and with the audiometry profiles of the tested subjects. In order to set robust standards for OAE evaluation and analysis, additional studies comparing different OAE hearing screening systems are needed.
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Jedrzejczak, W. Wiktor, Rafal Milner, Malgorzata Ganc, Edyta Pilka, and Henryk Skarzynski. "No Change in Medial Olivocochlear Efferent Activity during an Auditory or Visual Task: Dual Evidence from Otoacoustic Emissions and Event-Related Potentials." Brain Sciences 10, no. 11 (November 23, 2020): 894. http://dx.doi.org/10.3390/brainsci10110894.
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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.
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CORS, JEAN, ULRICH HEIMHOFER, THIERRY ADATTE, PETER A. HOCHULI, STEFAN HUCK, and TELM BOVER-ARNAL. "Climatic evolution across oceanic anoxic event 1a derived from terrestrial palynology and clay minerals (Maestrat Basin, Spain)." Geological Magazine 152, no. 4 (October 30, 2014): 632–47. http://dx.doi.org/10.1017/s0016756814000557.
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AbstractStudies dealing with the response of the continental biosphere to the environmental perturbations associated with Cretaceous oceanic anoxic events (OAEs) are comparatively rare. Here, a quantitative spore-pollen record combined with clay mineral data is presented, which covers the entire early Aptian OAE 1a interval (Forcall Formation, Maestrat basin, east Spain). The well-expressed OAE 1a carbon-isotope anomaly is paralleled by changes in the clay mineral assemblage and by a stepwise decline in the normalized frequency ofClassopollispollen (produced by xerophytic Cheirolepidiaceae) with lowest contents occurring during the positive δ13C shift. In contrast,AraucariacitesandInaperturopollenitespollen show a pronounced increase in relative abundance from low background values to become a significant component of the palynological assemblage during theClassopollisminimum. The observed changes in clay minerals and pollen distribution patterns are interpreted to reflect a major change in the composition of the hinterland vegetation of the Maestrat Basin, most probably due to short-lived but pronounced climatic cooling and changes in humidity. Temperature anomalies driven by organic carbon burial and associated CO2decline have been postulated for all major Mesozoic OAEs. The palynomorph record from the Iberian Maestrat basins indicates that the climax of this cooling episode was significantly delayed in comparison to the end of organic carbon-rich deposition in the world oceans.
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Bu, Xingkuan, Xiaolu Li, and Carlie Driscoll. "The Chinese Hearing Questionnaire for School Children." Journal of the American Academy of Audiology 16, no. 09 (October 2005): 687–97. http://dx.doi.org/10.3766/jaaa.16.9.6.
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Hearing loss is the most common of all disabilities in China, with three million of the 1.4 billion population affected. Recently, the release of an official neonatal hearing screening consensus has drawn attention to the importance of continued surveillance throughout childhood and the need for a system that is suited to the Chinese situation. The current research aimed to develop and evaluate a questionnaire for mass screening of school children in China. In Jiangsu Province, 317 rural students were screened using the Chinese Hearing Questionnaire for School Children (CHQS) and otoacoustic emissions (OAE). Test performance measures for the questionnaire method revealed average overall accuracy (A' = 0.54), while higher system accuracy was obtained for the OAEs (A' = 0.85). The OAE screening also produced very high efficiency and specificity values with reasonable sensitivity. Unlike the OAE protocol, the CHQS will require substantial modification to improve its sensitivity prior to utilization as a mass screening tool.
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Ruvalcaba Baroni, I., R. P. M. Topper, N. A. G. M. van Helmond, H. Brinkhuis, and C. P. Slomp. "Biogeochemistry of the North Atlantic during oceanic anoxic event 2: role of changes in ocean circulation and phosphorus input." Biogeosciences 11, no. 4 (February 20, 2014): 977–93. http://dx.doi.org/10.5194/bg-11-977-2014.
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Abstract. The geological record provides evidence for the periodic occurrence of water column anoxia and formation of organic-rich deposits in the North Atlantic Ocean during the mid-Cretaceous (hereafter called the proto-North Atlantic). Both changes in primary productivity and oceanic circulation likely played a role in the development of the low-oxygen conditions. Several studies suggest that an increased input of phosphorus from land initiated oceanic anoxic events (OAEs). Other proposed mechanisms invoke a vigorous upwelling system and an ocean circulation pattern that acted as a trap for nutrients from the Pacific Ocean. Here, we use a detailed biogeochemical box model for the proto-North Atlantic to analyse under what conditions anoxia could have developed during OAE2 (94 Ma). The model explicitly describes the coupled water, carbon, oxygen and phosphorus cycles for the deep basin and continental shelves. In our simulations, we assume the vigorous water circulation from a recent regional ocean model study. Our model results for pre-OAE2 and OAE2 conditions are compared to sediment records of organic carbon and proxies for photic zone euxinia and bottom water redox conditions (e.g. isorenieratane, carbon/phosphorus ratios). Our results show that a strongly elevated input of phosphorus from rivers and the Pacific Ocean relative to pre-OAE2 conditions is a requirement for the widespread development of low oxygen in the proto-North Atlantic during OAE2. Moreover, anoxia in the proto-North Atlantic is shown to be greatly influenced by the oxygen concentration of Pacific bottom waters. In our model, primary productivity increased significantly upon the transition from pre-OAE2 to OAE2 conditions. Our model captures the regional trends in anoxia as deduced from observations, with euxinia spreading to the northern and eastern shelves but with the most intense euxinia occurring along the southern coast. However, anoxia in the central deep basin is difficult to achieve in the model. This suggests that the ocean circulation used in the model may be too vigorous and/or that anoxia in the proto-North Atlantic was less widespread than previously thought.
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Ruvalcaba-Baroni, I., R. P. M. Topper, N. A. G. M. van Helmond, H. Brinkhuis, and C. P. Slomp. "Was the North Atlantic Ocean well-ventilated during Oceanic Anoxic Event 2 in the mid-Cretaceous?" Biogeosciences Discussions 10, no. 8 (August 8, 2013): 13231–76. http://dx.doi.org/10.5194/bgd-10-13231-2013.
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Abstract. The geological record provides evidence for the periodic occurrence of water column anoxia and formation of organic-rich deposits in the North Atlantic Ocean during the mid-Cretaceous (hereafter called proto-North Atlantic). Both changes in primary productivity and oceanic circulation likely played a role in the development of the low oxygen conditions. Several studies suggest that an increased input of phosphorus from land initiated oceanic anoxic events (OAEs). Other proposed mechanisms invoke a vigorous upwelling system and an ocean circulation pattern that acted as a trap for nutrients from the Pacific Ocean. Here, we use a detailed biogeochemical box model for the proto-North Atlantic to analyse under what conditions anoxia could have developed during OAE2 (94 Ma). The model explicitly describes the coupled water, carbon, oxygen and phosphorus cycles for the deep basin and continental shelves. In our simulations, we assume the vigorous water circulation from a recent regional ocean model study. Our model results for pre-OAE2 and OAE2 conditions are compared to sediment records of organic carbon and proxies for photic zone euxinia and bottom water redox conditions (e.g. isorenieratane, carbon/phosphorus ratios). Our results show that a strongly elevated input of phosphorus from rivers and the Pacific Ocean relative to pre-OAE2 conditions is a requirement for the widespread development of low oxygen in the proto-North Atlantic during OAE2. Moreover, anoxia in the proto-North Atlantic is shown to be greatly influenced by the oxygen concentration of Pacific bottom waters. In our model, primary productivity increased significantly upon the transition from pre-OAE2 to OAE2 conditions. Our model captures the regional trends in anoxia as deduced from observations, with euxinia spreading to the northern and eastern shelves but with the most intense euxinia occurring along the southern coast. However, anoxia in the central deep basin is difficult to achieve in the model. This suggests that the ocean circulation used in the model may be too vigorous and/or that anoxia in the proto-North Atlantic was less widespread than previously thought.
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De Groote, Evelien, Annelies Bockstael, Dick Botteldooren, Patrick Santens, and Miet De Letter. "The Effect of Parkinson's Disease on Otoacoustic Emissions and Efferent Suppression of Transient Evoked Otoacoustic Emissions." Journal of Speech, Language, and Hearing Research 64, no. 4 (April 14, 2021): 1354–68. http://dx.doi.org/10.1044/2020_jslhr-20-00594.
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Purpose Several studies have demonstrated increased auditory thresholds in patients with Parkinson's disease (PD) based on subjective tonal audiometry. However, the pathophysiological mechanisms underlying auditory dysfunction in PD remain elusive. The primary aim of this study was to investigate cochlear and olivocochlear function in PD using objective measurements and to assess the effect of dopaminergic medication on auditory function. Method Eighteen patients with PD and 18 gender- and age-matched healthy controls (HCs) were included. Patients with PD participated in medication on and off conditions. Linear mixed models were used to determine the effect of PD on tonal audiometry, transient evoked and distortion product otoacoustic emissions (OAEs), and efferent suppression (ES). Results Tonal audiometry revealed normal auditory thresholds in patients with PD for their age across all frequencies. OAE signal amplitudes demonstrated a significant interaction effect between group (PD vs. HC) and frequency, indicating decreased OAEs at low frequencies and increased OAEs at high frequencies in patients with PD. No significant differences were found between patients with PD and HCs regarding ES. In addition, no significant effect of medication status was found on auditory measurements in patients with PD. Conclusions Altered OAEs support the hypothesis of cochlear alterations in PD. No evidence was found for the involvement of the medial olivocochlear system. Altogether, OAEs may provide an objective early indicator of auditory alterations in PD and should complement subjective tonal audiometry when assessing and monitoring auditory function in PD.
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Spankovich, Christopher, Glenis R. Long, and Linda J. Hood. "Early Indices of Reduced Cochlear Function in Young Adults with Type-1 Diabetes Revealed by DPOAE Fine Structure." Journal of the American Academy of Audiology 30, no. 06 (June 2019): 459–71. http://dx.doi.org/10.3766/jaaa.17113.
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AbstractThe relationship between type-1 diabetes mellitus (DM) and cochlear dysfunction remains inconclusive.The purpose of this study was to examine otoacoustic emissions (OAEs) in normal-hearing young adults with type-1 DM as compared with matched controls and identify potential covariates influencing OAE findings.Cross-sectional study.N = 40 young adults aged 18–28 years including individuals with type-1 DM (n = 20) and age–gender matched controls (n = 20) with normal hearing sensitivity.Measures of pure-tone threshold sensitivity and OAEs, including distortion product otoacoustic emissions (DPOAEs), transient evoked OAEs, and DPOAE fine structure, were compared between groups. Covariates such as noise exposure and DM-related factors (e.g., duration of disease, glycated hemoglobin levels) were considered. Statistical analysis included analysis of variance and linear regression.Measures of hearing sensitivity and auditory function in both groups were comparable for all assays, except DPOAE fine structure. A reduced number of fine structure peaks and component amplitudes were found in the type-1 diabetes DM group with the primary difference in the reflection component.The results indicate that reduced cochlear function in young adults with type-1 DM can be revealed using DPOAE fine structure, suggesting potential clinical applications of DPOAE fine structure in early identification of cochlear pathology. Potential factors underlying these findings are discussed.
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Friedrich, Oliver, Silke Voigt, Tanja Kuhnt, and Mirjam C. Koch. "Repeated bottom-water oxygenation during OAE 2: timing and duration of short-lived benthic foraminiferal repopulation events (Wunstorf, northern Germany)." Journal of Micropalaeontology 30, no. 2 (September 1, 2011): 119–28. http://dx.doi.org/10.1144/0262-821x11-011.
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Abstract. Published proxy data for Oceanic Anoxic Event 2 (OAE 2 or Cenomanian–Turonian Boundary Event) and other mid-Cretaceous OAEs indicate widespread anoxic bottom-water conditions. However, increasing evidence shows that anoxia was not permanent but subject to significant fluctuations. We have generated X-ray fluorescence elemental concentration and benthic foraminiferal assemblage records for a short section of OAE 2 black shales from Wunstorf, northern Germany. Two intervals of low sulphur elemental concentration are interpreted as periods of increased oxygenation of bottom waters. This is supported by benthic foraminiferal assemblage data showing repopulation events associated with these intervals. These repopulation events are characterized mainly by the occurrence of agglutinated taxa, with Lingulogavelinella globosa being the only abundant calcareous species. This observation is interpreted in terms of short-term interruptions of the otherwise anoxic bottom-water environment. Comparison with repopulation events during OAE 1b and Quaternary sapropels make it reasonable to speculate that short-term cooling and an associated increase in bottom-water ventilation at the NW European shelf sea are the main trigger mechanisms for the observed repopulation events at Wunstorf. As source area for benthic foraminifera, shallower parts of the Lower Saxony basin are proposed.
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Them, Theodore R., Benjamin C. Gill, Andrew H. Caruthers, Angela M. Gerhardt, Darren R. Gröcke, Timothy W. Lyons, Selva M. Marroquín, Sune G. Nielsen, João P. Trabucho Alexandre, and Jeremy D. Owens. "Thallium isotopes reveal protracted anoxia during the Toarcian (Early Jurassic) associated with volcanism, carbon burial, and mass extinction." Proceedings of the National Academy of Sciences 115, no. 26 (June 11, 2018): 6596–601. http://dx.doi.org/10.1073/pnas.1803478115.
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For this study, we generated thallium (Tl) isotope records from two anoxic basins to track the earliest changes in global bottom water oxygen contents over the Toarcian Oceanic Anoxic Event (T-OAE; ∼183 Ma) of the Early Jurassic. The T-OAE, like other Mesozoic OAEs, has been interpreted as an expansion of marine oxygen depletion based on indirect methods such as organic-rich facies, carbon isotope excursions, and biological turnover. Our Tl isotope data, however, reveal explicit evidence for earlier global marine deoxygenation of ocean water, some 600 ka before the classically defined T-OAE. This antecedent deoxygenation occurs at the Pliensbachian/Toarcian boundary and is coeval with the onset of initial large igneous province (LIP) volcanism and the initiation of a marine mass extinction. Thallium isotopes are also perturbed during the T-OAE interval, as defined by carbon isotopes, reflecting a second deoxygenation event that coincides with the acme of elevated marine mass extinctions and the main phase of LIP volcanism. This suggests that the duration of widespread anoxic bottom waters was at least 1 million years in duration and spanned early to middle Toarcian time. Thus, the Tl data reveal a more nuanced record of marine oxygen depletion and its links to biological change during a period of climatic warming in Earth’s past and highlight the role of oxygen depletion on past biological evolution.
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De Keyser, Kim, Miet De Letter, Evelien De Groote, Patrick Santens, Durk Talsma, Dick Botteldooren, and Annelies Bockstael. "Systematic Audiological Assessment of Auditory Functioning in Patients With Parkinson's Disease." Journal of Speech, Language, and Hearing Research 62, no. 12 (December 18, 2019): 4564–77. http://dx.doi.org/10.1044/2019_jslhr-h-19-0097.
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Purpose Alterations in primary auditory functioning have been reported in patients with Parkinson's disease (PD). Despite the current findings, the pathophysiological mechanisms underlying these alterations remain unclear, and the effect of dopaminergic medication on auditory functioning in PD has been explored insufficiently. Therefore, this study aimed to systematically investigate primary auditory functioning in patients with PD by using both subjective and objective audiological measurements. Method In this case–control study, 25 patients with PD and 25 age-, gender-, and education-matched healthy controls underwent an audiological test battery consisting of tonal audiometry, short increment sensitivity index, otoacoustic emissions (OAEs), and speech audiometry. Patients with PD were tested in the on- and off-medication states. Results Increased OAE amplitudes were found when patients with PD were tested without dopaminergic medication. In addition, speech audiometry in silence and multitalker babble noise demonstrated higher phoneme scores for patients with PD in the off-medication condition. The results showed no differences in auditory functioning between patients with PD in the on-medication condition and healthy controls. No effect of disease stage or motor score was evident. Conclusions This study provides evidence for a top-down involvement in auditory processing in PD at both central and peripheral levels. Most important, the increase in OAE amplitude in the off-medication condition in PD is hypothesized to be linked to a dysfunction of the olivocochlear efferent system, which is known to have an inhibitory effect on outer hair cell functioning. Future studies may clarify whether OAEs may facilitate an early diagnosis of PD.
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Mazumder, Rajarshi, Samson Kamya Lubowa, Noriko Salamon, Nicholas J. Jackson, Michael Kawooya, Pamela Rosemary Akun, Ronald Anguzu, et al. "Comparison of Structural Changes in Nodding Syndrome and Other Epilepsies Associated WithOnchocerca volvulus." Neurology - Neuroimmunology Neuroinflammation 10, no. 2 (December 21, 2022): e200074. http://dx.doi.org/10.1212/nxi.0000000000200074.
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Background and ObjectiveNodding syndrome (NS) is a unique childhood-onset epileptic disorder that occurs predominantly in several regions of sub-Saharan Africa. The disease has been associated withOnchocerca volvulus (Ov)–induced immune responses and possible cross-reactivity with host proteins. The aim of this study was to compare structural changes in the brain on MRI between NS and other forms of onchocerciasis-associated epilepsies (OAEs) and to relate structural changes to the Ov-induced immune responses and level of disability.MethodsThirty-nine children with NS and 14 age-matched participants with other forms of OAE from an endemic region in Uganda underwent detailed clinical examination, serologic evaluation (including Ov-associated antibodies to Ov-16 and Hu-leiomodin-1) and quantitative volumetric analysis of brain MRIs (1.5 T scanner) using Neuroreader, a cloud-based software.ResultsCerebral and cerebellar atrophy were the predominant features in both NS and OAE. On quantitative volumetric analysis, participants with NS had larger ventricular volumes compared with participants with OAE, indicative of increased global cortical atrophy (pcorr= 0.036). Among children with NS, severe disability correlated with higher degree of atrophy in the gray matter volume (pcorr= 0.009) and cerebellar volume (pcorr= 0.009). NS cases had lower anti-Ov-16 IgG signal-to-noise ratios than the OAE cases (p< 0.01), but no difference in the levels of the Hu-leiomodin-1 antibodies (p= 0.64). The levels of Ov-associated antibodies did not relate to the degree of cerebral or cerebellar atrophy in either NS or OAE cases.DiscussionThis is the first study to show that cerebral and cerebellar atrophy correlated with the severity of NS disability, providing an imaging marker for these endemic epileptic disorders that until now have remained poorly characterized. Both NS and OAE have cerebral and cerebellar atrophy, and the levels of Ov-associated antibodies do not seem to be related to the structural changes on MRI.
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Löhr, S. C., and M. J. Kennedy. "Organomineral nanocomposite carbon burial during Oceanic Anoxic Event 2." Biogeosciences Discussions 11, no. 5 (May 12, 2014): 6815–44. http://dx.doi.org/10.5194/bgd-11-6815-2014.
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Abstract. Organic carbon (OC) enrichment in sediments deposited during Oceanic Anoxic Events (OAEs) is commonly attributed to elevated productivity and marine anoxia. We find that OC enrichment in the late Cenomanian aged OAE2 at Demerara Rise was controlled by co-occurrence of anoxic bottom-water, sufficient productivity to saturate available mineral surfaces and variable deposition of high surface area detrital smectite clay. Redox indicators show consistently oxygen-depleted conditions, while a strong correlation between OC concentration and sediment mineral surface area (R2=0.92) occurs across a range of TOC values from 9–33%. X-ray diffraction data indicates intercalation of OC in smectite interlayers while electron, synchrotron infrared and X-ray microscopy show an intimate association between clay minerals and OC, consistent with preservation of OC as organomineral nanocomposites and aggregates rather than discrete, μm-scale pelagic detritus. Since the consistent ratio between TOC and mineral surface area suggests that excess OC relative to surface area is lost, we propose that it is the varying supply of smectite that best explains variable organic enrichment against a backdrop of continuous anoxia, which is conducive to generally high TOC during OAE2 at Demerara Rise. Smectitic clays are unique in their ability to form stable organomineral nanocomposites and aggregates that preserve organic matter, and are common weathering products of continental volcanic deposits. An increased flux of smectite coinciding with high carbon burial is consistent with evidence for widespread volcanism during OAE2, so that organomineral carbon burial may represent a potential feedback to volcanic degassing of CO2.
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Prieve, Beth A., Tracy Schooling, Rebecca Venediktov, and Nicole Franceschini. "An Evidence-Based Systematic Review on the Diagnostic Accuracy of Hearing Screening Instruments for Preschool- and School-Age Children." American Journal of Audiology 24, no. 2 (June 2015): 250–67. http://dx.doi.org/10.1044/2015_aja-14-0065.
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Purpose The purpose of this article is to conduct an evidence-based systematic review on the accuracy of pure-tone or otoacoustic emission (OAE) screening for identifying hearing loss in preschool- and school-age children. Method A systematic search of the literature published between 1975 and 2013 was conducted. Articles meeting the selection criteria were critically appraised for quality. Selection criteria required that behavioral thresholds be measured in children failing the screen and in at least a subset of children passing the screen. Sensitivity and specificity were used to calculate positive and negative likelihood ratios that could be compared between instruments. Results Eighteen studies were included in the final analysis. There was considerable variability among studies on stimulus levels, response criteria, and definition of hearing loss. Approximately half of positive and negative likelihood ratio pairs for OAEs (52%) and pure-tone screening (45%) were considered suggestive or informative for identifying hearing loss. Conclusions Both pure-tone and OAE screening can identify hearing loss in preschool- and school-age children. Studies that compared both tools in the same population concluded that pure-tone screening had higher sensitivity than OAE screening and thus was considered the preferred tool. Future research should incorporate standard stimulus levels, response criteria, and definitions of hearing loss.
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Wagreich, M. ""OAE 3" – regional Atlantic organic carbon burial during the Coniacian–Santonian." Climate of the Past 8, no. 5 (September 20, 2012): 1447–55. http://dx.doi.org/10.5194/cp-8-1447-2012.
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Abstract. The Coniacian–Santonian time interval is the inferred time of oceanic anoxic event 3 (OAE 3), the last of the Cretaceous OAEs. A detailed look on the temporal and spatial distribution of organic-rich deposits attributed to OAE 3 suggests that black shale occurrences are restricted to the equatorial to mid-latitudinal Atlantic and adjacent basins, shelves and epicontinental seas like parts of the Caribbean, the Maracaibo Basin and the Western Interior Basin, and are largely absent in the Tethys, the North Atlantic, the southern South Atlantic, and the Pacific. Here, oxic bottom waters prevailed as indicated by the widespread occurrence of red deep-marine CORBs (Cretaceous Oceanic Red Beds). Widespread CORB sedimentation started during the Turonian after Oceanic Anoxic Event 2 (OAE 2) except in the Atlantic realm where organic-rich strata continue up to the Santonian. The temporal distribution of black shales attributed to OAE 3 indicates that organic-rich strata do not define a single and distinct short-time event, but are distributed over a longer time span and occur in different basins during different times. This suggests intermittent and regional anoxic conditions from the Coniacian to the Santonian. A comparison of time-correlated high-resolution δ13C curves for this interval indicates several minor positive excursions of up to 0.5‰, probably as a result of massive organic carbon burial cycles in the Atlantic. Regional wind-induced upwelling and restricted deep basins may have contributed to the development of anoxia during a time interval of widespread oxic conditions, thus highlighting the regional character of inferred OAE 3 as regional Atlantic event(s).
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Wong, Lye-Yeng, Francisca Espinoza, Karen Mojica Alvarez, Dave Molter, and James E. Saunders. "Otoacoustic Emissions in Rural Nicaragua: Cost Analysis and Implications for Newborn Hearing Screening." Otolaryngology–Head and Neck Surgery 156, no. 5 (February 1, 2017): 877–85. http://dx.doi.org/10.1177/0194599817696306.
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Objective (1) Determine the incidence and risk factors for congenital hearing loss. (2) Perform cost analysis of screening programs. Study Design Proportionally distributed cross-sectional survey. Setting Jinotega, Nicaragua. Subjects and Methods Otoacoustic emissions (OAEs) were used to screen 640 infants <6 months of age from neonatal intensive care unit, institutional, and home birth settings. Data on 15 risk factors were analyzed. Cost of 4 implementation strategies was studied: universal screening, screening at the regional health center (RHC), targeted screening, and screening at the RHC plus targeted screening. Cost-effectiveness analysis over 10 years was based on disability-adjusted life year estimates, with the World Health Organization standard of cost-effectiveness ratio (CER) / gross domestic product (GDP) <3, with GDP set at $4884.15. Results Thirty-eight infants failed the initial OAE (5.94%). In terms of births, 325 (50.8%) were in the RHC, 69 (10.8%) in the neonatal intensive care unit, and 29 (4.5%) at home. Family history and birth defect were significant in univariate analysis; birth defect was significant in multivariate analysis. Cost-effectiveness analysis demonstrated that OAE screening is cost-effective without treatment (CER/GDP = 0.06-2.00) and with treatment (CER/GDP = 0.58-2.52). Conclusions Our rate of OAE failures was comparable to those of developed countries and lower than hearing loss rates noted among Nicaraguan schoolchildren, suggesting acquired or progressive etiology in the latter. Birth defects and familial hearing loss correlated with OAE failure. OAE screening of infants is feasible and cost-effective in rural Nicaragua, although highly influenced by estimated hearing loss severity in identified infants and the high travel costs incurred in a targeted screening strategy.
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Wagreich, M. ""OAE 3" – a low- to mid-latitude Atlantic oceanic event during the Coniacian-Santonian." Climate of the Past Discussions 8, no. 2 (April 16, 2012): 1209–27. http://dx.doi.org/10.5194/cpd-8-1209-2012.
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Abstract. The Coniacian-Santonian time interval is the inferred time of oceanic anoxic event 3 (OAE 3), the last of the Cretaceous OAEs. A detailed look on the temporal and spatial distribution of organic-rich deposits attributed to OAE 3 suggests that black shale occurrences are restricted to the equatorial to mid-latitudinal Atlantic and adjacent basins, shelves and epicontinental seas like parts of the Caribbean, the Maracaibo Basin and the Western Interior Basin, and are largely absent in the Tethys, the North Atlantic, the southern South Atlantic, and the Pacific. Here, oxic bottom waters prevailed as indicated by the widespread occurrence of red deep-marine CORBs (Cretaceous Oceanic Red Beds). Widespread CORB sedimentation started during the Turonian after Oceanic Anoxic Event 2 (OAE 2) except in the Atlantic realm where organic-rich strata continue up to the Santonian. The temporal distribution of black shales attributed to OAE 3 indicates that organic-rich strata do not define a single and distinct short-time event, but are distributed over a longer time span and occur in different basins during different times. This suggests intermittent and regional anoxic conditions from the Coniacian to the Santonian. A comparison of time-correlated high-resolution δ13C curves for this interval indicates several minor positive excursions of about 0.5 permil, probably as a result of massive organic carbon burial cycles in the Atlantic. Regional wind-induced upwelling and silled deep basins may have contributed to the development of anoxia during a global oxic time interval, thus highlighting the regional character of inferred OAE 3 as an Atlantic anoxic event (AAE).
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Garcia, Marieflor Cristy M., Charlotte M. Chiong, Generoso T. Abes, and Ryner Jose C. Carrillo. "Accuracy of Reflexive Behavioral (“Baah”) Test in the Screening for Hearing Impairment in Infants Six Months Old and Below." Philippine Journal of Otolaryngology-Head and Neck Surgery 27, no. 1 (June 29, 2012): 6–11. http://dx.doi.org/10.32412/pjohns.v27i1.543.
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Objective: To determine the prevalence of hearing loss among infants six months old and below sent for newborn hearing screening in our institution, and to measure the accuracy, sensitivity, specificity and positive predictive values of reflexive behavioral (“Baah”) test in detecting hearing loss in infants.Methods: Design: Cross-sectional study Setting: Ear Unit of a tertiary government hospital Participants: Infants less than Six months old sent for newborn hearing screening at the Ear Unit of a tertiary government hospital from April to September, 2011 were recruited. All participants were tested with OAE for hearing screening. OAE was also used as the standard for evaluating hearing impairment. The reflexive behavioral (“Baah”) test was then done using the human voice as a loud sound stimulus, and the response recorded were auropalpebral, startle and blinking response to the sound. Thesensitivity, specificity, accuracy, positive and negative predictive value of the test was then measured.Results: From April to September 2011, a total of 101 patients were tested, with a male to female ratio of 1.1:1 (53 males, 48 females). The prevalence of hearing impairment in this study population was 6.9% (7 out of 101). The reflexive behavioral (“Baah”) test was found to have sensitivity of 71.4%, specificity of 95.7%, accuracy rate of 94%, positive predictive value of 55.6% and negative predictive value of 97.8%.Conclusion: The reflexive behavioral (“Baah”) test shows potential as an accurate, acceptable and cost-effective screening tool to identify infants that may be at higher risk for hearing impairment. This test may aid the health care providers, in areas without OAEs, in identifying infants who are in need further hearing diagnostic evaluation, with OAEs or other hearing tests. It is recommended that the “Baah” test be implemented in the community to test its reproducibility in a larger population and outside the hospital setting.Keywords: reflexive behavioral test, “Baah” test, otoacoustic emission, hearing screening
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Dot, José Alejandro Méndez, José Méndez Baamonde, Dayana Reyes, and Rommel Whilchy. "The Cogollo Group and the oceanic anoxic events 1a and 1b, Maracaibo basin, Venezuela." Brazilian Journal of Geology 45, suppl 1 (August 2015): 41–61. http://dx.doi.org/10.1590/2317-4889201530192.
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ABSTRACTCarbonates of Cogollo Group (Apón, Lisure and Maraca formations) constitute the broader calcareous platform system originated during Aptian and Albian of Cretaceous in north-western South America, Maracaibo Basin, Venezuela. On the shallow shelf, a variety of calcareous sedimentary facies were deposited during marine transgressive and regressive cycles. Some of them developed porosity and constitute important hydrocarbon reservoirs. Due to some major marine transgressions, from early Aptian, the anoxic environment and characteristic facies of a pelagic environment moved from the outer slope and basin to the shallow shelf, during specific time intervals, favouring the sedimentation of organic matter-rich facies, which correspond to the oceanic anoxic events (OAEs) 1a and 1b. The source rock of Machiques Member (Apón Formation) was deposited during early Aptian OAE 1a (~ 120 Ma). The source rock of Piché Member, located at the top of the Apón Formation, was deposited during late Aptian OAE 1b (~ 113 Ma). Finally, La Luna Formation, from Cenomanian, that covers the OAE 2 (~ 93 Ma), represents the most important source rock in the Maracaibo Basin. In this way and based on sedimentological and organic geochemistry results from the determinations performed on 247 samples belonging to six cores in the Maracaibo Basin, we propose these two organic-rich levels, deposited on the shallow shelf of the Cogollo Group, as "effective source rocks", additional to La Luna Formation, with oil migration in relatively small distances to the porosity facies.
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MUSCENTE, A. D., ROWAN C. MARTINDALE, JAMES D. SCHIFFBAUER, ABBY L. CREIGHTON, and BROOKE A. BOGAN. "TAPHONOMY OF THE LOWER JURASSIC KONSERVAT-LAGERSTÄTTE AT YA HA TINDA (ALBERTA, CANADA) AND ITS SIGNIFICANCE FOR EXCEPTIONAL FOSSIL PRESERVATION DURING OCEANIC ANOXIC EVENTS." PALAIOS 34, no. 11 (November 4, 2019): 515–41. http://dx.doi.org/10.2110/palo.2019.050.
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ABSTRACT Konservat-Lagerstätten provide the most complete snapshots of ancient organisms and communities in the fossil record. In the Mesozoic, these deposits are rarely found in marine facies outside Oceanic Anoxic Event (OAE) intervals, suggesting that OAEs set the stage for exceptional fossil preservation. Although anoxia does not guarantee survival of non-biomineralized tissues or articulated skeletons, other OAE phenomena may promote their conservation. Here, we test this hypothesis with a taphonomic analysis of the Konservat-Lagerstätte in the black shales and siltstones of the Jurassic Fernie Formation at Ya Ha Tinda (Alberta, Canada). This deposit contains crustacean cuticles, coleoid gladii with ink sacs and mantle tissues, and articulated skeletons of fish, crinoids, and ichthyosaurs. The fossils were preserved in the Pliensbachian and Toarcian (Early Jurassic) when euxinic conditions were common in the area, in part, due to the ∼183 Ma Toarcian OAE. Some of the fossils contain carbonaceous material, but the majority consists of apatite minerals, and phosphatic gladii demonstrate that some animals were preserved through secondary phosphate mineralization. Phosphatization generally occurs within phosphate-rich sediment, but oceanic anoxia causes sediment to release phosphorus and prevents animals from colonizing seafloor habitats. Accordingly, we propose that the animals were preserved during brief episodes of bottom water oxia and/or dysoxia, when the environment would have been most favorable to benthic communities and phosphate mineralization. In this setting, phosphatization may have been fueled by phosphate delivery from continental weathering in response to climatic warming, ocean upwelling of eutrophic water, and/or nutrient trapping by anoxia in the basin.
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Simmons, Jeffrey L., and Kathryn Laudin Beauchaine. "Auditory Neuropathy: Case Study with Hyperbilirubinemia." Journal of the American Academy of Audiology 11, no. 06 (June 2000): 337–47. http://dx.doi.org/10.1055/s-0042-1748063.
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AbstractAuditory neuropathy (AN) has been described in the literature as presenting with a combination of audiometric findings that include elevated behavioral audiometric thresholds, auditory brainstem response findings that are not consistent with audiometric findings, poor speech recognition, and present otoacoustic emissions (OAEs) and/or cochlear microphonics. Since the availability of clinical OAE testing, AN has come to be identified with increasing frequency; however, incidence and prevalence figures are unavailable. There is a great deal of discussion about the accurate diagnosis of AN, its characteristics, and its treatment. Some of this discussion is occurring on the Internet and over the telephones. The need to continue to provide information in accessible peer-reviewed journals is paramount. Following a review of the literature, a case study is presented of a boy who was diagnosed with AN as a newborn. He experienced hyperbilirubinemia and other neonatal health complications. His educational intervention was managed elsewhere until recently. Information is presented about the progression of the case over a 5–year period that includes audiologic data and communication development results. Abbreviations: AN = auditory neuropathy, CI = cochlear implant, CM = cochlear microphonic, DPOAE = distortion product otoacoustic emissions, DSL = Desired Sensation Level, IHC = inner hair cell, MRI = magnetic resonance imaging, OAE = otoacoustic emission, OHC = outer hair cell, SS = standard scores, TC = total communication
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Jenkyns, Hugh C. "Transient cooling episodes during Cretaceous Oceanic Anoxic Events with special reference to OAE 1a (Early Aptian)." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 376, no. 2130 (September 3, 2018): 20170073. http://dx.doi.org/10.1098/rsta.2017.0073.
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The two major oceanic anoxic events of the Cretaceous, those of the Early Aptian (OAE 1a) and the Cenomanian–Turonian boundary (OAE 2), registered some of the highest temperatures reconstructed for the Cretaceous Period, and are thought to be related to the input of volcanically derived carbon dioxide from one or more Large Igneous Provinces. Widely distributed deposition of marine organic matter, the hallmark of OAEs, and intensified silicate weathering in response to a globally accelerated hydrological cycle and/or reaction of seawater with freshly extruded basalt, are both potential mechanisms whereby the content of atmospheric carbon dioxide could have been drawn down to promote cooling, on the assumption that this potential effect was not offset by increased addition of this volcanically derived greenhouse gas. Reduction in the supply of such carbon dioxide, with deposition of organic matter and silicate weathering continuing at the same rate, could also have produced cooling. A transient fall in temperature and increase in marine dissolved oxygen levels is well documented for OAE 2, in the form of the so-called Plenus Cold Event or Benthic Oxic Event, associated with southward invasion of certain boreal faunas and an increase in many redox-sensitive and/or chalcophilic elements in seawater caused by temporary loss of anoxic–euxinic sinks as basalt–seawater interaction continued apace. High-resolution studies of OAE 1a show at least three cooling episodes of probable global distribution, one of which (recorded in the stratigraphy of the so-called C4 Segment) is documented at high enough resolution to show correlation with an increase in carbon-isotope values that was probably due to a rise in the quantities of organic matter being buried globally, with consequent potential drawdown of atmospheric CO 2 and/or reduction in volcanic input of this greenhouse gas. Both calcium- and lithium-isotope records suggest an increase in silicate weathering over the OAE 1a interval but current relatively low-resolution records cannot at present be tied to any one cooling episode, although the lowest Li-isotope values do derive from the C4 Segment. Evidence for reoxygenation of the ocean during the transient cooling episodes of OAE 1a is meagre, due to the lack of suitable sedimentary archives, although a negative sulfur-isotope excursion in a Pacific shallow-water carbonate section, which can be interpreted as due to oxidation of pyrite and/or sulfur-rich organic matter in the global ocean, suggests that this phenomenon may also have been a feature of the C4 Segment. Further work is required to elucidate the similarities and differences between OAE 2 and OAE 1a, but both phenomena are demonstrably global in reach and represent major disturbances to the carbon cycle with attendant effects on marine temperatures. This article is part of a discussion meeting issue ‘Hyperthermals: rapid and extreme global warming in our geological past’.
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Löhr, S. C., and M. J. Kennedy. "Organomineral nanocomposite carbon burial during Oceanic Anoxic Event 2." Biogeosciences 11, no. 18 (September 18, 2014): 4971–83. http://dx.doi.org/10.5194/bg-11-4971-2014.
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Abstract. Organic carbon (OC) enrichment in sediments deposited during Oceanic Anoxic Events (OAEs) is commonly attributed to elevated productivity and marine anoxia. We find that OC enrichment in the late Cenomanian aged OAE 2 at the Demerara Rise was controlled by the co-occurrence of anoxic bottom water, sufficient productivity to saturate available mineral surfaces, and variable deposition of high surface area detrital smectite clay. Redox indicators show consistently oxygen-depleted conditions, while a strong correlation between OC concentration and sediment mineral surface area (R2 = 0.92) occurs across a range of total organic carbon (TOC) values from 9 to 33%. X-ray diffraction data indicate the intercalation of OC in smectite interlayers, while electron, synchrotron infrared and X-ray microscopy show an intimate association between clay minerals and OC, consistent with preservation of OC as organomineral nanocomposites and aggregates rather than discrete, μm-scale pelagic detritus. Since the consistent ratio between TOC and mineral surface area suggests that excess OC relative to surface area is lost, we propose that it is the varying supply of smectite that best explains variable organic enrichment against a backdrop of continuous anoxia, which is conducive to generally high TOC during OAE 2 at the Demerara Rise. Smectitic clays are unique in their ability to form stable organomineral nanocomposites and aggregates that preserve organic matter, and are common weathering products of continental volcanic deposits. An increased flux of smectite coinciding with high carbon burial is consistent with evidence for widespread volcanism during OAE 2, so that organomineral carbon burial may represent a potential feedback to volcanic degassing of CO2.
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Guinan, John J., Bradford C. Backus, Watjana Lilaonitkul, and Vered Aharonson. "Medial Olivocochlear Efferent Reflex in Humans: Otoacoustic Emission (OAE) Measurement Issues and the Advantages of Stimulus Frequency OAEs." Journal of the Association for Research in Otolaryngology 4, no. 4 (June 13, 2003): 521–40. http://dx.doi.org/10.1007/s10162-002-3037-3.
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de Boer, Jessica, A. Roger D. Thornton, and Katrin Krumbholz. "What is the role of the medial olivocochlear system in speech-in-noise processing?" Journal of Neurophysiology 107, no. 5 (March 1, 2012): 1301–12. http://dx.doi.org/10.1152/jn.00222.2011.
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The medial olivocochlear (MOC) bundle reduces the gain of the cochlear amplifier through reflexive activation by sound. Physiological results indicate that MOC-induced reduction in cochlear gain can enhance the response to signals when presented in masking noise. Some previous studies suggest that this “antimasking” effect of the MOC system plays a role in speech-in-noise perception. The present study set out to reinvestigate this hypothesis by correlating measures of MOC activity and speech-in-noise processing across a group of normal-hearing participants. MOC activity was measured using contralateral suppression of otoacoustic emissions (OAEs), and speech-in-noise processing was measured by measuring the effect of noise masking on performance in a consonant-vowel (CV) discrimination task and on auditory brain stem responses evoked by a CV syllable. Whereas there was a significant correlation between OAE suppression and both measures of speech-in-noise processing, the direction of this correlation was opposite to that predicted by the antimasking hypothesis, in that individuals with stronger OAE suppression tended to show greater noise-masking effects on CV processing. The current results indicate that reflexive MOC activation is not always beneficial to speech-in-noise processing. We propose an alternative to the antimasking hypothesis, whereby the MOC system benefits speech-in-noise processing through dynamic (e.g., attention- and experience-dependent), rather than reflexive, control of cochlear gain.
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Boothalingam, Sriram, Chris Allan, Prudence Allen, and David W. Purcell. "The Medial Olivocochlear Reflex Is Unlikely to Play a Role in Listening Difficulties in Children." Trends in Hearing 23 (January 2019): 233121651987094. http://dx.doi.org/10.1177/2331216519870942.
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The medial olivocochlear reflex (MOCR) has been implicated in several auditory processes. The putative role of the MOCR in improving speech perception in noise is particularly relevant for children who complain of listening difficulties (LiD). The hypothesis that the MOCR may be impaired in individuals with LiD or auditory processing disorder has led to several investigations but without consensus. In two related studies, we compared the MOCR functioning of children with LiD and typically developing (TD) children in the same age range (7–17 years). In Study 1, we investigated ipsilateral, contralateral, and bilateral MOCR using forward-masked click-evoked otoacoustic emissions (CEOAEs; n = 17 TD, 17 LiD). In Study 2, we employed three OAE types: CEOAEs ( n = 16 TD, 21 LiD), stimulus frequency OAEs ( n = 21 TD, 30 LiD), and distortion product OAEs ( n = 17 TD, 22 LiD) in a contralateral noise paradigm. Results from both studies suggest that the MOCR functioning is not significantly different between the two groups. Some likely reasons for differences in findings among published studies could stem from the lack of strict data quality measures (e.g., high signal-to-noise ratio, control for the middle ear muscle reflex) that were enforced in the present study. The inherent variability of the MOCR, the subpar reliability of current MOCR methods, and the heterogeneity in auditory processing deficits that underlie auditory processing disorder make detecting clinically relevant differences in MOCR function impractical using current methods.