Transient Emissions Research Articles

Functional changes in the human auditory cortex in ageing.

Hearing loss, presbycusis, is one of the most common sensory declines in the ageing population. Presbycusis is characterised by a deterioration in the processing of temporal sound features as well as a decline in speech perception, thus indicating a possible central component. With the aim to explore the central component of presbycusis, we studied the function of the auditory cortex by functional MRI in two groups of elderly subjects (>65 years) and compared the results with young subjects (<lt;30 years). The elderly group with expressed presbycusis (EP) differed from the elderly group with mild presbycusis (MP) in hearing thresholds measured by pure tone audiometry, presence and amplitudes of transient otoacoustic emissions (TEOAE) and distortion-product oto-acoustic emissions (DPOAE), as well as in speech-understanding under noisy conditions. Acoustically evoked activity (pink noise centered around 350 Hz, 700 Hz, 1.5 kHz, 3 kHz, 8 kHz), recorded by BOLD fMRI from an area centered on Heschl’s gyrus, was used to determine age-related changes at the level of the auditory cortex. The fMRI showed only minimal activation in response to the 8 kHz stimulation, despite the fact that all subjects heard the stimulus. Both elderly groups showed greater activation in response to acoustical stimuli in the temporal lobes in comparison with young subjects. In addition, activation in the right temporal lobe was more expressed than in the left temporal lobe in both elderly groups, whereas in the young control subjects (YC) leftward lateralization was present. No statistically significant differences in activation of the auditory cortex were found between the MP and EP groups. The greater extent of cortical activation in elderly subjects in comparison with young subjects, with an asymmetry towards the right side, may serve as a compensatory mechanism for the impaired processing of auditory information appearing as a consequence of ageing.

Otoacoustic Emissions as Cochlear Function Analyser in Children With Language Disorders

Introduction and objectivesSpeech perception that takes place in the cochlea is involved in the process of language. The objective was to describe the findings in transient otoacoustic emissions in children with language problems before and after 6 months of speech therapy. MethodsThere were 17 children with language problems between 3 and 6 years of age diagnosed with anarthric language delay (expressive and mixed language disorder). They underwent medical history, otoscopy, intelligence level testing, initial language test, tympanometry of 226Hz, audiometry and transient otoacoustic emission test. ResultsWe evaluated the 17 patients again after 6 months of attending speech therapy. The percentage of overall reproducibility of transient otoacoustic emissions in both ears was adequate to perform frequency analysis. We found a statistically significant difference (P≤.01) in the frequency of 1kHz reproducibility when comparing results before and after therapy in the right ear. There was a significant difference (P≤.05) when comparing the results of audiometry at frequencies of 0.5, 1.5, 2, 4 and 8kHz in the right ear and a highly significant difference (P=.001) in the frequency of 3kHz in the left ear. ConclusionsThe analysis of sound through the cochlea is involved in the process of language acquisition. A poor processing of speech sounds in the peripheral system could result in poor processing at the central level. Consequently, it is important to consider our results when making a diagnosis and carrying out rehabilitation treatment in children with language disorders.

Mercury exposure in a riverside Amazon population, Brazil: a study of the ototoxicity of methylmercury.

Introduction Mercury poisoning causes hearing loss in humans and animals. Acute and long-term exposures produce irreversible peripheral and central auditory system damage, and mercury in its various forms of presentation in the environment is ototoxic. Objective We investigated the otoacoustic emissions responses in a riverside population exposed to environmental mercury by analyzing the inhibitory effect of the medial olivocochlear system (MOCS) on transient otoacoustic emissions (TEOAE). Methods The purpose of the research was to evaluate the entire community independently of variables of sex and age. All of the participants were born and lived in a riverside community. After otolaryngologic evaluation, participants were received tympanometry, evaluation of contralateral acoustic reflexes, pure tone audiometry, and recording of TEOAEs with nonlinear click stimulation. Hair samples were collect to measure mercury levels. Results There was no significant correlation between the inhibitory effect of the MOCS, age, and the level of mercury in the hair. Conclusions The pathophysiological effects of chronic exposure may be subtle and nonspecific and can have a long period of latency; therefore, it will be important to monitor the effects of mercury exposure in the central auditory system of the Amazon population over time. Longitudinal studies should be performed to determine whether the inhibitory effect of the MOCS on otoacoustic emissions can be an evaluation method and diagnostic tool in populations exposed to mercury.

Tinnitus in adolescents: the start of the vulnerability of the auditory pathways.

Although tinnitus is an increasingly common symptom, few studies have assessed its prevalence or incidence among adolescents. To assess whether the presence of tinnitus in adolescents is associated with minimal hearing damage, evaluated through high-frequency audiometry (HFA), otoacoustic emission (OAE), and loudness discomfort level (LDL). The sample comprised 168 adolescents of a private school (61.3% boys; mean age 14.1 years old; standard deviation=2). All of them completed a questionnaire about tinnitus and hypersensitivity to sounds (sound intolerance), and then underwent otoscopy, pure-tone audiometry, HFA, LDL, transient and distortion product otoacoustic emissions (TOAE and DPOAE), and tinnitus pitch/loudness matching (the latter only in those with tinnitus). Participants were later divided into three groups: with no tinnitus (n=73, 43.4%), with sporadic tinnitus (n=47, 28%), and with constant tinnitus (n=48, 28.6%). No significant difference was observed between the groups regarding audiometry thresholds in frequencies from 0.25 to 16 kHz, or TOAE and DPOAE. However, the LDL in adolescents with constant tinnitus was significantly lower than that in other groups, suggesting hypersensitivity to sounds. There was no evidence of minimal hearing damage in the audiometry and OAE. Nonetheless, the decreased LDL in adolescents with constant tinnitus suggests that their auditory system is more sensitive. Therefore, this may be the first sign of vulnerability to sounds. Future medium- to long-term monitoring of these students may show whether they will begin a process of functional impairment, altering hearing thresholds, and OAE.

Comparative multivariate analyses of transient otoacoustic emissions and distorsion products in normal and impaired hearing.

Background and aimThe clinical utility of otoacoustic emissions as a noninvasive objective test of cochlear function has been long studied. Both transient otoacoustic emissions and distorsion products can be used to identify hearing loss, but to what extent they can be used as predictors for hearing loss is still debated. Most studies agree that multivariate analyses have better test performances than univariate analyses. The aim of the study was to determine transient otoacoustic emissions and distorsion products performance in identifying normal and impaired hearing loss, using the pure tone audiogram as a gold standard procedure and different multivariate statistical approaches.MethodsThe study included 105 adult subjects with normal hearing and hearing loss who underwent the same test battery: pure-tone audiometry, tympanometry, otoacoustic emission tests. We chose to use the logistic regression as a multivariate statistical technique. Three logistic regression models were developed to characterize the relations between different risk factors (age, sex, tinnitus, demographic features, cochlear status defined by otoacoustic emissions) and hearing status defined by pure-tone audiometry. The multivariate analyses allow the calculation of the logistic score, which is a combination of the inputs, weighted by coefficients, calculated within the analyses. The accuracy of each model was assessed using receiver operating characteristics curve analysis. We used the logistic score to generate receivers operating curves and to estimate the areas under the curves in order to compare different multivariate analyses.ResultsWe compared the performance of each otoacoustic emission (transient, distorsion product) using three different multivariate analyses for each ear, when multi-frequency gold standards were used. We demonstrated that all multivariate analyses provided high values of the area under the curve proving the performance of the otoacoustic emissions. Each otoacoustic emission test presented high values of area under the curve, suggesting that implementing a multivariate approach to evaluate the performances of each otoacoustic emission test would serve to increase the accuracy in identifying the normal and impaired ears. We encountered the highest area under the curve value for the combined multivariate analysis suggesting that both otoacoustic emission tests should be used in assessing hearing status. Our multivariate analyses revealed that age is a constant predictor factor of the auditory status for both ears, but the presence of tinnitus was the most important predictor for the hearing level, only for the left ear. Age presented similar coefficients, but tinnitus coefficients, by their high value, produced the highest variations of the logistic scores, only for the left ear group, thus increasing the risk of hearing loss. We did not find gender differences between ears for any otoacoustic emission tests, but studies still debate this question as the results are contradictory. Neither gender, nor environment origin had any predictive value for the hearing status, according to the results of our study.ConclusionLike any other audiological test, using otoacoustic emissions to identify hearing loss is not without error. Even when applying multivariate analysis, perfect test performance is never achieved. Although most studies demonstrated the benefit of using the multivariate analysis, it has not been incorporated into clinical decisions maybe because of the idiosyncratic nature of multivariate solutions or because of the lack of the validation studies.

In-situ Laser Induced Incandescence technique for measurement of full stream fast transient soot emissions in real-time

The Laser Induced Incandescence technique (LII) is an emerging optical method for the reliable spatially and temporally resolved measurement of soot concentration and potentially for monitoring primary soot particle size. Due to its origin, this method appears to be suitable for the measurement of fast transient soot emissions from Diesel engines, which form the main fraction of total emissions during standardised test cycles. Current existing commercial LII devices require modifications in the exhaust gas flow, dilution, and measuring with a partial stream in a preconditioned cell. The results from the development of a single window access in-situ LII setup for rapid measurement of soot emission during the combustion process from a Diesel production engine, suitable for direct full stream, measurements in the tail-pipe without the need for dilution or a sampling cell are presented here. Furthermore, the issue of the optical window cleaning, background incandescence due to the laser – tailpipe interaction and possible suppression of disrupted emission by means of time delay constant is addressed. The obtained and corrected in-situ LII results are further compared to commercially available devices for the measurement of soot emissions. Static and dynamic emission tests have been performed in order to demonstrate the viability and applicability of proposed single access optical probe for full stream fast transient soot emission measurement in real-time.

Assessment of levels of otoacoustic emission response in neonates with perinatal asphyxia

ObjectiveTo evaluate the effects of perinatal asphyxia on the level of the response to transient otoacoustic emissions in infants. MethodsOtoacoustic emissions in 154 neonates were performed: 54 infants who suffered asphyxia at birth, measured by Apgar score and medical diagnosis, and 100 infants without risk were compared. Scores less than 4 in the first minute and/or less than 6 in the fifth minute were considered as “low Apgar”. Statistical analysis of the data was performed using the Kruskal, Wilcoxon, and Mann-Whitney nonparametric tests. ResultsLower levels of response were observed in transient otoacoustic emission in the group that suffered perinatal asphyxia, with significant values for the frequencies 2,000, 3,000, and 4,000 Hz in the right ear, and 2,000 and 4,000 Hz in the left ear. ConclusionsThe analysis of the intrinsic characteristics of the otoacoustic emissions evidenced low performance of outer hair cells in neonates who had perinatal asphyxia, which may affect the development of listening skills in this population.

Avaliação dos níveis de resposta das emissões otoacústicas em neonatos com asfixia perinatal

ObjectiveTo evaluate the effects of perinatal asphyxia on the level of the response to transient otoacoustic emissions in infants. MethodsOtoacoustic emissions in 154 neonates were performed: 54 infants who suffered asphyxia at birth, measured by Apgar score and medical diagnosis, and 100 infants without risk were compared. Scores less than 4 in the first minute and/or less than 6 in the fifth minute were considered as “low Apgar”. Statistical analysis of the data was performed using the Kruskal, Wilcoxon, and Mann-Whitney nonparametric tests. ResultsLower levels of response were observed in transient otoacoustic emission in the group that suffered perinatal asphyxia, with significant values for the frequencies 2,000, 3,000, and 4,000Hz in the right ear, and 2,000 and 4,000Hz in the left ear. ConclusionsThe analysis of the intrinsic characteristics of the otoacoustic emissions evidenced low performance of outer hair cells in neonates who had perinatal asphyxia, which may affect the development of listening skills in this population.

Emisiones otoacústicas como analizador de la función coclear en niños con problemas de lenguaje

Introduction and objectivesSpeech perception that takes place in the cochlea is involved in the process of language. The objective was to describe the findings in transient otoacoustic emissions in children with language problems before and after 6 months of speech therapy. MethodsThere were 17 children with language problems between 3 and 6 years of age diagnosed with anarthric language delay (expressive and mixed language disorder). They underwent medical history, otoscopy, intelligence level testing, initial language test, tympanometry of 226Hz, audiometry and transient otoacoustic emission test. ResultsWe evaluated the 17 patients again after 6 months of attending speech therapy. The percentage of overall reproducibility of transient otoacoustic emissions in both ears was adequate to perform frequency analysis. We found a statistically significant difference (P≤0.01) in the frequency of 1kHz reproducibility when comparing results before and after therapy in the right ear. There was a significant difference (P≤0.05) when comparing the results of audiometry at frequencies of 0.5, 1.5, 2, 4 and 8kHz in the right ear and a highly significant difference (P=0.001) in the frequency of 3kHz in the left ear. ConclusionsThe analysis of sound through the cochlea is involved in the process of language acquisition. A poor processing of speech sounds in the peripheral system could result in poor processing at the central level. Consequently, it is important to consider our results when making a diagnosis and carrying out rehabilitation treatment in children with language disorders.

Split ratio control in mini–dilution tunnels for measurement of steady–state and transient emissions from heavy duty diesel engines

A 91–tube multi–tube–type mini–dilution tunnel with and without a split ratio control unit was used to study the emissions from a heavy duty diesel engine, operated over several steady–state modes and transient test cycles. The split ratio, or the gas induction ratio, relates the volume of sampled raw exhaust to the total volume of engine exhaust that is generated. Determination of the split ratio and the ability to maintain this ratio around a certain theoretical value, 1/91 in the study, was critical to the entire sampling process. Results presented herein, demonstrate the ability of the split ratio control unit to improve dramatically the splitting accuracy of the 91–tube splitter, over both steady–state and transient cycles. Even when operated over severe changes in engine conditions of the transient cycles, the split ratio control unit was able to maintain an average pressure differential of nearly zero. However, the transient response of the PID controller needs further improvements.

High‐speed distributed acquisition network for fast transient measurement

In power substations, switching operations of circuit breakers and disconnect switches generate transient electromagnetic emissions, which may interfere with the normal operations of electronic equipments. This study introduces the design of a novel wireless transient measurement system for measuring or monitoring transient electromagnetic emissions in power substations. Unlike traditional transient measurement systems that use several standalone waveform recording equipment, the presented system, adopting novel network measurement concept, works as a truly automatically controlled interactive data acquisition multi-node network, and has the ability to provide time-correlated data from numerous sensors. The accuracy of time correlation is smaller than 1.4 μs. As a result, it provides excellent scalability and is well suited for the measurement of analogue signals spread over a large physical space with time synchronisation. Another major difference is that the new system uses wireless links and programmable devices to replace cables and data acquisition equipment of currently available systems, thus making the new measurement system more compact, flexible and much more powerful. The designed measurement units could do both time-domain measurement and real time spectrum analysis.

Optimal energy management of a series hybrid vehicle with combined fuel economy and low-emission objectives

A series hybrid powertrain provides ultimate freedom in controlling the engine. The flexibility enabled with hybridization creates chances for a synergistic approach, in which the hybrid supervisory control can be augmented to address both the emissions and the efficiency. In this paper, two policy optimization techniques are proposed, namely stochastic dynamic programming and neurodynamic programming, for designing power management controllers. These controllers are then compared with a baseline rule-based controller. The intention is to investigate the additional benefits possible through application of policy optimization algorithms and a systematic framework capable of representing complex system-level effects. The power management of a series hydraulic hybrid vehicle is pursued as a sequential decision-making problem under uncertainty (stochastic control). The low energy density of the hydraulic accumulator adds to the control challenge. First, stochastic dynamic programming and neurodynamic programming are applied to design a controller based on the fuel economy objective. The problem is subsequently expanded to include minimization of transient diesel engine emissions. This poses additional challenges due to the increased state space. The problem is computationally intractable by stochastic dynamic programming and is solved using the newly proposed neurodynamic programming framework. Finally, the supervisory controllers are implemented and evaluated using simulations and an engine-in-the-loop facility. It is shown that, by designing an intelligent multi-objective controller, significant reduction in both the fuel consumption and the emissions can be achieved compared with strategies which focus solely on the fuel consumption.

Avaliação audiológica em funcionários de um hospital público expostos a ruído

Objetivo caracterizar e comparar a audição de funcionários de um hospital público expostos a níveis de ruído ocupacional máximos superiores e inferiores a 85dB(A). Métodos trata-se de um estudo clínico, com 39 funcionários de um hospital público, divididos de acordo com o nível de exposição ao ruído: 20 indivíduos sob exposição máxima superior a 85dB(A) (Grupo 1) e 19 indivíduos sob exposição máxima inferior a 85dB(A) (Grupo 2). Foi realizada avaliação audiológica básica e emissões otoacústicas evocadas por estímulo transiente e produto de distorção. Resultados ambos os grupos apresentaram limiares de audibilidade normais. Contudo, observou-se ausência de respostas em 87,5% no Grupo 1 e 60,5% no Grupo 2 no teste de emissões otoacústicas evocadas por estímulo transiente, com diferença estatística. O Grupo 1 mostrou menor amplitude de respostas também às emissões otoacústicas produto de distorção, sendo a frequência de 6kHz a única alterada em ambos os grupos. Conclusão os níveis de pressão sonora e o tempo de exposição não influenciam os limiares auditivos tonais. As emissões otoacústicas mostraram-se mais alteradas quanto maior o nível de pressão sonora e tempo de exposição.

The High-Altitude Water Cherenkov Observatory

The High Altitude Water Cherenkov (HAWC) observatory is a large field of view, continuously operated, TeV gamma-ray experiment under construction at 4,100 m a.s.l. in Mexico. The HAWC observatory will have an order of magnitude better sensitivity, angular resolution, and background rejection than its predecessor, the Milagro experiment. The improved performance will allow us to detect both transient and steady emissions, to study the Galactic diffuse emission at TeV energies, and to measure or constrain the TeV spectra of GeV gamma-ray sources. In addition, HAWC will be the only ground-based instrument capable of detecting prompt emission from gamma-ray bursts above 50 GeV. The HAWC observatory will consist of an array of 300 water Cherenkov detectors (WCDs), each with four photomultiplier tubes. This array is currently under construction on the flanks of the Sierra Negra volcano near the city of Puebla, Mexico. The first thirty WCDs (forming an array approximately the size of Milagro) were deployed in Summer 2012, and 100 WCDs will be taking data by May, 2013. We present in this paper the motivation for constructing the HAWC observatory, the status of the deployment, and the first results from the constantly growing array.

Auditory brainstem response in term and preterm infants with neonatal complications: the importance of the sequential evaluation.

Introduction Literature data are not conclusive as to the influence of neonatal complications in the maturational process of the auditory system observed by auditory brainstem response (ABR) in infants at term and preterm. Objectives Check the real influence of the neonatal complications in infants by the sequential auditory evaluation. Methods Historical cohort study in a tertiary referral center. A total of 114 neonates met inclusion criteria: treatment at the Universal Neonatal Hearing Screening Program of the local hospital; at least one risk indicator for hearing loss; presence in both evaluations (the first one after hospital discharge from the neonatal unit and the second one at 6 months old); all latencies in ABR and transient otoacoustic emissions present in both ears. Results The complications that most influenced the ABR findings were Apgar scores less than 6 at 5 minutes, gestational age, intensive care unit stay, peri-intraventricular hemorrhage, and mechanical ventilation. Conclusion Sequential auditory evaluation is necessary in premature and term newborns with risk indicators for hearing loss to correctly identify injuries in the auditory pathway.

Time–frequency analysis of transient evoked-otoacoustic emissions in individuals with auditory neuropathy spectrum disorder

The aim of the study was to describe and quantify the cochlear active mechanisms in individuals with Auditory Neuropathy Spectrum Disorders (ANSD). Transient Evoked Otoacoustic Emissions (TEOAEs) were recorded in 15 individuals with ANSD and 22 individuals with normal hearing. TEOAEs were analyzed by Wavelet transform method to describe and quantify the characteristics of TEOAEs in narrow-band frequency regions. It was noted that the amplitude of TEOAEs was higher and latency slightly shorter in individuals with ANSD compared to normal hearing individuals at low and mid frequencies. The increased amplitude and reduced latencies of TEOAEs in ANSD group could be attributed to the efferent system damage, especially at low and mid frequencies seen in individuals with ANSD. Thus, wavelet analysis of TEOAEs proves to be another important tool to understand the patho-physiology in individuals with ANSD.

Development of non-intrusive monitoring for reactive switching of high voltage circuit breaker

High-voltage circuit breakers are among the most important equipments for ensuring the efficient and safe operation of an electric power system. On occasion, circuit breaker operators may wish to check whether equipment is performing satisfactorily and whether controlled switching systems are producing reliable and repeatable stress control. Monitoring of voltage and current waveforms during switching using established methods will provide information about the magnitude and frequency of voltage transients as a result of re-ignitions and restrikes. However, high frequency waveform measurement requires shutdown of circuit breaker and use of specialized equipment. Two utilities, Hydro-Québec in Canada and Powerlink Queensland in Australia, have been working on the development and application of a non-intrusive, cost-effective and flexible diagnostic system for monitoring high-voltage circuit breakers for reactive switching. The proposed diagnostic approach relies on the non-intrusive assessment of key parameters such as operating times, prestrike characteristics, re-ignition and restrike detection. Transient electromagnetic emissions have been identified as a promising means to evaluate the abovementioned parameters non-intrusively.This paper describes two complimentary methods developed concurrently by Powerlink and Hydro-Québec. Also, return of experiences on the application to capacitor bank and shunt reactor switching is presented.

Dynamic Vapor Generator That Simulates Transient Odor Emissions of Victims Entrapped in the Voids of Collapsed Buildings

The design, development, and validation of a dynamic vapor generator are presented. The generator simulates human scent (odor) emissions from trapped victims in the voids of collapsed buildings. The validation of the device was carried out using a reference detector: a quadrupole mass spectrometer equipped with a pulsed sampling (PS-MS) system. A series of experiments were conducted for evaluating the simulator's performance, defining types and weights of different factors, and proposing further optimization of the device. The developed device enabled the production of stable and transient odor profiles in a controllable and reproducible way (relative standard deviation, RSD < 11%) at ppbv to low ppmv concentrations and allowed emission durations up to 30 min. Moreover, the factors affecting its optimum performance (i.e., evaporation chamber temperature, air flow rate through the mixing chamber, air flow rate through the evaporation chamber, and type of compound) were evaluated through an analysis of variance (ANOVA) tool revealing the next steps toward optimizing the generator. The developed simulator, potentially, can also serve the need for calibrating and evaluating the performance of analytical devices (e.g., gas chromatographers, ion mobility spectrometers, mass spectrometers, sensors, e-noses) in the field. Furthermore, it can contribute in better training of urban search and rescue (USaR) canines.

Determination of GHG Emissions, Fuel Consumption and Thermal Efficiency for Real World Urban Driving using a SI Probe Car

A SI probe car, defined here as a normal commercial car equipped with GPS, in-vehicle FTIR tailpipe emission measurement and real time fuel consumption measurement systems, and temperature measurements, was used for measuring greenhouse gas emissions including CO2, N2O and CH4 under real world urban driving conditions. The vehicle used was a EURO4 emission compliant SI car. Two real world driving cycles/routes were designed and employed for the tests, which were located in a densely populated area and a busy major road representing a typical urban road network. Eight trips were conducted at morning rush hours, day time non-peak traffic periods and evening off peak time respectively. The aim is to investigate the impacts of traffic conditions such as road congestion, grade and turnings on fuel consumption, engine thermal efficiency and emissions. The time aligned vehicle moving parameters with fuel consumption and emission data enabled the micro-analysis of the correlations between these parameters. The trip average data for fuel consumption, thermal efficiency and emissions etc were calculated. The impact of vehicle's transient movements and traffic events on emissions were studied. VSP (Vehicle Specific Power) has been used for the determination of engine power output. The results show that the transient emissions were dominated by sharp accelerations occurred at traffic light and pedestrian crossing. The trip average CO2 and CH4 emissions had a good linear correlation with vehicle's average speed which is directly related to vehicle idle periods but no clear correlation between vehicle's speed and N2O emissions.

Effects of Type 2 Diabetes on Otoacoustic Emissions and the Medial Olivocochlear Reflex

To demonstrate if cochleopathy in patients with type 2 diabetes with normal audiometric hearing threshold can be detected with otoacoustic emissions or medial olivocochlear (MOC) reflex measurements. Cross-sectional study. Tertiary university teaching hospital. The study involved 40 type 2 diabetic patients and 24 healthy volunteers. All participants who showed normal otoscopic findings, hearing thresholds, and acoustic admittance were included. Cochlear activity of participants was evaluated by means of distortion product otoacoustic emissions (DPOAEs) and transient otoacoustic emissions (TOAEs). The MOC reflex was evoked with contralateral acoustic stimulation and recorded with DPOAEs and TOAEs. A comparison of DPOAE and TOAE levels with a t test between patient and control groups revealed no significant difference (P > .05). A comparison of the MOC reflex response between the 2 groups also revealed no statistically significant difference (P > .05). Although decreased OAE amplitude levels were found in diabetic patients, there was no statistically significant difference in OAEs and MOC reflex. Additional studies are needed to evaluate the role of OAEs and MOC reflex in normal-hearing patients with diabetes.