Distortion Product Otoacoustic Emissions Amplitudes Research Articles

Impact of endolymphatic hydrops on DPOAE in subjects with normal to mild hearing loss.

The increased endolymph volume affects a shift in the organ of Corti and basilar membrane in ears with endolymphatic hydrops (EH), which might affect distortion-product otoacoustic emissions (DPOAE) by altering the operating point of the outer hair cells. We investigated how changes in DPOAE are related to the distribution site of EH. Prospective study. Among 403 patients with hearing or vestibular symptoms who underwent contrast-enhanced magnetic resonance imaging (MRI) for the diagnosis of EH and subsequent DPOAE testing, subjects whose hearing levels on pure tone audiometry were ≤35dB at all frequencies were included in this study. In patients with EH on MRI, the presence and amplitude of DPOAE were evaluated between groups with hearing levels of ≤25dB at all frequencies versus hearing levels of >25dB at one or more frequencies. There were no differences in the distribution of EH between groups. The amplitude of DPOAE had no clear correlation with the presence of EH. However, in both groups, there was a significantly higher probability of the presence of a DPOAE response from 1001 to 6006Hz in cases with EH in the cochlea. Among patients whose hearing levels were ≤35dB at all frequencies, better responses on DPOAE testing were found in subjects with EH in the cochlea. Alteration of DPOAEs in the early stages of hearing impairment could indicate morphological changes in the inner ear with altered basilar membrane compliance due to EH. 4.

Development of an audiological assessment and diagnostic model for high occupational noise exposure.

To explore the diagnostic auditory indicators of high noise exposure and combine them into a diagnostic model of high noise exposure and possible development of hidden hearing loss (HHL). We recruited 101 young adult subjects and divided them according to noise exposure history into high-risk and low-risk groups. All subjects completed demographic characteristic collection (including age, noise exposure, self-reported hearing status, and headset use) and related hearing examination. The 8kHz (P = 0.039) and 10kHz (P = 0.005) distortion product otoacoustic emission amplitudes (DPOAE) (DPs) in the high-risk group were lower than those in the low-risk group. The amplitudes of the summating potential (SP) (P = 0.017) and action potential (AP) (P = 0.012) of the electrocochleography (ECochG) in the high-risk group were smaller than those in the low-risk group. The auditory brainstem response (ABR) wave III amplitude in the high-risk group was higher than that in the low-risk group. When SNR = -7.5dB (P = 0.030) and -5dB (P = 0.000), the high-risk group had a lower speech discrimination score than that of the low-risk group. The 10kHz DPOAE DP, ABR wave III amplitude and speech discrimination score under noise with SNR = -5dB were combined to construct a combination diagnostic indicator. The area under the ROC curve was 0.804 (95% CI 0.713-0.876), the sensitivity was 80.39%, and the specificity was 68.00%. We expect that high noise exposure can be detected early with this combined diagnostic indicator to prevent HHL or sensorineural hearing loss (SNHL). ChiCTR2200057989, 2022/3/25.

Subclinical Hearing Deficits in Noise-Exposed Firefighters.

Noise-induced hearing loss (NIHL) is the most prevalent occupational disease in the world and firefighters are at increased risk of NIHL due to their frequent exposure to hazardous levels of noise during service. Adverse effects of NIHL include acceleration of age-related hearing loss and an increased risk of cognitive decline. A critical challenge in addressing NIHL is the delayed clinical presentation of symptoms and lack of sensitive tools for early detection. To study the early clinical symptoms of NIHL in this high-risk group, we collected hearing function data including behavioral audiometric thresholds and distortion product otoacoustic emissions (DPOAEs) in 176 firefighters during annual physical assessments. Results revealed significant deficits in cochlear outer hair cell function in the presence of normal audiograms. Additionally, 55% of firefighters self-reported changes in hearing, while 20% self-reported concerns about their balance. This study is the first to characterize DPOAEs in firefighters who display decreased DPOAE amplitudes with increasing years in the fire service. These effects were observed even when controlling for hearing loss and age and are suggestive of a link between hearing loss and occupational exposure to hazardous noise.

A Correlational Analysis between Audiometric Pure-tone Averages and Distortion Product Otoacoustic Emissions.

Hearing loss severely affects human speech communication and the quality of life, and efficient hearing screening can help hearing function diagnosis and subsequent hearing rehabilitation. Pure-tone audiometry test and distortion-product otoacoustic emission (DPOAE) measurement are two commonly-used clinical techniques for hearing loss diagnosis, and they were developed based on different mechanisms in a hearing process. Early work investigated the relation between audiometric thresholds and DPOAE measurements. The present work aimed to use a simple linear fitting to estimate audiometric pure-tone threshold averages (PTAs) from DPOAE signal-to-noise-ratio (SNR) measurements, i.e., DPOAE amplitude minus the mean noise floor. Audiometric PTA values and DPOAE SNRs were measured from both ears of 30 listeners with normal hearing or mild-to-moderate hearing loss. The DPOAE SNR measurements of 4 distortion products (i.e., 2fl-f2= 1, 2, 4 and 8 kHz) were combined with a linear prediction model, and correlated with the PTA values. Data analysis showed moderate high correlation coefficients (i.e., r=0.84 and 0.64) for the left and right ears, respectively. The results of the present work demonstrate the possibility to estimate the behavioral audiometric PTA values from the objective DPOAE SNR measurements for hearing loss diagnosis.

Hearing Loss in Offspring Exposed to Antiretrovirals During Pregnancy and Breastfeeding.

Over 27 million people worldwide currently receive daily antiretroviral therapy for the management of HIV/AIDS. In order to prevent the continued spread of HIV, the World Health Organization (WHO) recommends the use of highly active antiretroviral therapy by pregnant and nursing women. There is currently little research into the auditory effects of this therapy on children exposed during pregnancy and breastfeeding, and research to date on the direct effects of antiretroviral exposure on the auditory system is inconclusive. The current study examined the effects of WHO-recommended first-line antiretrovirals in a well-controlled animal model to evaluate the potential for auditory damage and dysfunction following these exposures. Female breeding mice were each exposed to one of four antiretroviral cocktails or a vehicle control once daily during pregnancy and breastfeeding. Offspring of these mice had their auditory status evaluated after weaning using auditory brainstem responses and distortion-product otoacoustic emissions (DPOAEs). Auditory brainstem response thresholds following antiretroviral exposure during gestation and breastfeeding showed elevated thresholds and increased wave latencies in offspring of exposed mice when compared to unexposed controls, but no corresponding decrease in DPOAE amplitude. These differences in threshold were small and so may explain the lack of identified hearing loss in antiretroviral-exposed children during hearing screenings at birth. Minimal degrees of hearing impairment in children have been correlated with decreased academic performance and impaired auditory processing, and so these findings, if also seen in human children, suggest significant implications for children exposed to antiretrovirals during development despite passing hearing screenings at birth.

The effect of increase in blood glucose level on hearing loss

ObjectivePrevious studies have shown that hearing function is also vulnerable to the effects of diabetes mellitus which can be shown by brainstem auditory evoked potential and distortion product otoacoustic emission recordings. This study aimed to investigate the changes of brainstem auditory evoked potential and distortion product otoacoustic emission in hyperglycemia and whether there is a relationship between reactive oxygen substances production and hearing deterioration in the rat model. Methods25 streptozotocin induced diabetic rats were divided into three groups: control, high blood glucose, and diabetes mellitus. Brainstem auditory evoked potential and distortion product otoacoustic emission were recorded, and thiobarbituric acid reactive substances levels were measured in the brainstem tissue. ResultsAt 8 kHz, the latencies of I, II, III, IV, and V brainstem auditory evoked potential waves in high blood glucose and diabetes mellitus groups were elongated, at 16 kHz, only these wave latencies of the diabetes mellitus group were prolonged compared with the control group. A significant decrease was also found in distortion product otoacoustic emission amplitudes at 4, 6, 8, and 10 kHz in the high blood glucose and diabetes mellitus groups compared to the control group. There was a significant increase in thiobarbituric acid reactive substances values due to the increase in blood glucose levels in the high blood glucose and diabetes mellitus groups compared to the control group. ConclusionThese results suggested that high blood glucose levels may cause hearing impairment not only in the diabetic state but also in the period of hyperglycemia before the onset of manifest diabetes mellitus and reactive oxygen substances may play an important role in the pathophysiology of diabetes mellitus. We suggest that regulating high glucose levels even before the onset of manifest diabetes mellitus may prevent hazardous effects on hearing function. Level of evidenceLevel 3.

COVID-19 during pregnancy and its impact on the developing auditory system

BackgroundThis study compared distortion product otoacoustic emissions (DPOAEs) and click-evoked auditory brainstem responses (ABRs) recorded from infants whose mother had Covid-19 during pregnancy (Covid-19 group) to infants whose mother did not have Covid-19 (Control group) during pregnancy. MethodsThis study retrospectively examined records of infants in the Covid-19 group (n = 15) and control group (n = 46) who had distortion product otoacoustic emissions (DPOAEs) and click-evoked auditory brainstem responses (ABRs) recorded as part of their clinical assessment. DPOAE amplitudes, absolute latencies (I, III, and V), and I-V interpeak intervals were examined. ResultsDPOAE amplitudes were similar between the Covid-19 group and the control group. The absolute latency of wave I was similar between groups. But absolute latencies III and V and I-V interpeak intervals of the Covid-19 group were significantly prolonged compared to the control group. ConclusionCovid-19 infection and its complications during pregnancy may not affect the cochlear function but may affect the functioning of the auditory brainstem.

Comparison of otoacoustic emissions in tinnitus and hyperacusis in adults with normal hearing sensitivity

Objective To investigate the effect of tinnitus and/or hyperacusis on distortion product otoacoustic emission (DPOAE) measures in adults with normal hearing thresholds from 0.25 to 8 kHz, while accounting for extended high-frequency (EHF) thresholds. Design A behavioural study consisted of comprehensive audiological assessment, validated tinnitus and hyperacusis questionnaires, DPOAE amplitudes and input/output (I/O) functions. Study sample Data of 56 participants with normal hearing were included for the analysis. Participants were categorised into four groups: (1) without tinnitus or hyperacusis, (2) with tinnitus only, (3) with hyperacusis only, and (4) with both tinnitus and hyperacusis. Results The groups with tinnitus showed elevated EHF thresholds compared with those without tinnitus. DPOAE amplitudes were not significantly affected by tinnitus and/or hyperacusis status; however, they were significantly affected by EHF thresholds. Further, no appreciable differences in DPOAE I/O functions were found across groups. Conclusions The reported non-significant differences in DPOAEs in individuals with tinnitus and/or hyperacusis do not support a peripheral mechanism or an interaction between peripheral and central mechanisms underlying tinnitus or hyperacusis. Our findings, however, suggest the need to assess basal cochlear function (e.g. EHF thresholds) for a better understanding of differences in DPOAE measures in tinnitus and/or hyperacusis.

Audiological findings in individuals diagnosed with COVID-19

PurposeIt is thought that COVID-19 may cause hearing loss, but its effects on the hearing system are not clear. This study aimed to reveal the effects of COVID-19 on the auditory system by using various audiological measurement methods in individuals diagnosed with COVID-19. MethodsThirty individuals between the ages of 18–45, who were diagnosed with COVID-19 by PCR at least one month ago, and had no pre-COVID-19 hearing loss complaints, constituted the test group. Thirty individuals aged between 18 and 30 years and who had no history of hearing loss constituted the control group. Audiological evaluations of all participants were made with pure-tone audiometry, high-frequency audiometry, transient-evoked otoacoustic emission (TEOAE), distortion product otoacoustic emission (DPOAE), and auditory brainstem response (ABR) measurements. ResultsA significant difference was found between the groups at all high frequencies between 4 and 14 kHz (p < 0.05). TEOAE amplitudes at 1500 Hz, 2000 Hz and 4000 Hz frequencies and DPOAE amplitudes at 4003 Hz and higher frequencies were significantly lower in the test group (p < 0.05). While there was a significant difference between the I, III and V absolute latencies between the groups (p < 0.05), there was no significant difference between the I-III, III-V and I-V interpeak latencies (p > 0.05) as a result of the ABR test. ConclusionThis study showed that COVID-19 can cause cochlear damage, especially at high frequencies. More studies are needed to determine the effects of COVID-19 on the auditory system.

Is there any difference in hearing function between surgical and natural menopause?

ABSTRACT This study was designed to examine cochlear function in surgical postmenopausal women and natural menopause. Three groups, each including 20 patients, were formed: surgical menopause (SM), natural menopause (NM), and healthy controls who had not yet gone through menopause. Conventional audiometry (0.125–8 kHz), ultra-high frequency audiometry (10–16 kHz), and otoacoustic emission (OAE) tests were used in the evaluation of the patients. Almost all the hearing thresholds were significantly poorer in the menopause groups than in the control group (p < .05). However, the amplitudes of the healthy controls were higher in transient evoked otoacoustic emissions (TEOAEs), especially in many frequencies of distortion product otoacoustic emissions (DPOAEs) (p < .05). In the SM group, all the frequencies between 0.125 and 10 kHz for the right ear, and 1, 2, 6 and 8 kHz air-conduction hearing thresholds for the left ear were significantly poorer compared to the NM group (p < .05). There was also a significant decrease in the 4, 6, and 8 kHz DPOAE amplitudes of the SM group compared to the NM group (p < .05). This study showed that postmenopausal women, in particular those with SM had significantly poorer hearing thresholds and lower OAE amplitudes. Menopause may be a potential risk factor for the development of hearing loss in women.

Evaluation of the effects of Covid-19 on cochleovestibular system with audiovestibular tests.

The purpose of the present study was to investigate the effects of COVID-19 on audiovestibular system with Transiently Evoked Distortion Otoacoustic Emissions (TOAE), Distortion Product Otoacoustic Emissions (DPOAE), video head impulse test (vHIT) and caloric test. Audiovestibular findings of 24 patients with moderate/severe COVID-19 and 24 healthy controls were compared using pure tone audiometry, tympanometry, TOAE, DPOAE, caloric test, and vHIT. On audiometry, the pure tone averages of the COVID-19 patients were higher than the controls (P = .038). The TEOAE amplitudes at 4000 and 5000Hz (P = .006 and P < .01), and DPOAE amplitudes at 3000, 6000, and 8000Hz (P < .001, P = .003 and P < .001) were significantly lower in COVID-19 patients compared to the controls. On vestibular tests, there was no significant difference between the caloric test results of the patients and the controls (P > .05). On vHIT testing, amplitudes of right semicircular canal was found to be significantly lower in COVID-19 group compared to the control group (P = .008). COVID-19 may affect inner ear functions causing a subtle damage in the outer hair cells and lateral semicircular canals. It must be kept in mind that COVID-19 may cause cochleovestibular problems.

What is responsible for cochlear damage in patients with obstructive sleep apnea? Hypoxia or snoring noise?

Abstract Aim: Our aim in this study was to determine early cochlear changes caused by hypoxia and snoring noise in patients with Obstructive sleep apnea Syndrome and to examine the relationship of these changes with polysomnography parameters. Materials and Methods: A total of 149 patients with symptoms of snoring and sleep apnea who underwent polysomnography were included in this study. We formed a patient and control group based on the apnea-hypopnea index. We compared the audiometric parameters and the Distortion Product Otoacoustic Emission amplitudes of the groups. We evaluated Polysomnography parameters such as snoring number, snoring index, oxygen desaturation index, minimum pO2, mean pO2, pO2 ≤88%, which affect these results, by correlation. Results: High frequency audiometry and high frequency Distortion Product Otoacoustic Emission amplitudes showed statistically significant differences in the Obstructive Sleep Apnea Syndrome group compared to the control group (p&lt;0.001). PO2 ≤88% affected high frequency audiometry and mean pO2 affected high frequency Distortion Product Otoacoustic Emission amplitudes more than snoring number and snoring index. (p&lt;0.001). Conclusion: İn patients with OSAS, the inner ear is affected by hypoxia and snoring. However, the effect of hypoxia on cochlear dysfunction is greater than snoring noise. High-frequency audiometry and Distortion Product Otoacoustic Emission can guide in the early period to determine cochlear damage.

Combined antioxidants and anti-inflammatory therapies fail to attenuate the early and late phases of cyclodextrin-induced cochlear damage and hearing loss

Niemann-Pick C1 (NPC1) is a fatal neurodegenerative disease caused by aberrant cholesterol metabolism. The progression of the disease can be slowed by removing excess cholesterol with high-doses of 2-hyroxypropyl-beta-cyclodextrin (HPβCD). Unfortunately, HPβCD causes hearing loss; the initial first phase involves a rapid destruction of outer hair cells (OHCs) while the second phase, occurring 4–6 weeks later, involves the destruction of inner hair cells (IHCs), pillar cells, collapse of the organ of Corti and spiral ganglion neuron degeneration. To determine whether the first and/or second phase of HPβCD-induced cochlear damage is linked, in part, to excess oxidative stress or neuroinflammation, rats were treated with a single-dose of 3000 mg/kg HPβCD alone or together with one of two combination therapies. Each combination therapy was administered from 2-days before to 6-weeks after the HPβCD treatment. Combination 1 consisted of minocycline, an antibiotic that suppresses neuroinflammation, and HK-2, a multifunctional redox modulator that suppresses oxidative stress. Combination 2 was comprised of minocycline plus N-acetyl cysteine (NAC), which upregulates glutathione, a potent antioxidant. To determine if either combination therapy could prevent HPβCD-induced hearing impairment and cochlear damage, distortion product otoacoustic emissions (DPOAE) were measured to assess OHC function and the cochlear compound action potential (CAP) was measured to assess the function of IHCs and auditory nerve fibers. Cochleograms were prepared to quantify the amount of OHC, IHC and pillar cell (PC) loss. HPβCD significantly reduced DPOAE and CAP amplitudes and caused significant OHC, IHC and OPC losses with losses greater in the high-frequency base of the cochlea than the apex. Neither minocycline + HK-2 (MIN+ HK-2) nor minocycline + NAC (MIN+NAC) prevented the loss of DPOAEs, CAPs, OHCs, IHCs or IPCs caused by HPβCD. These results suggest that oxidative stress and neuroinflammation are unlikely to play major roles in mediating the first or second phase of HPβCD-induced cochlear damage. Thus, HPβCD-induced ototoxicity must be mediated by some other unknown cell-death pathway possibly involving loss of trophic support from damaged support cells or disrupted cholesterol metabolism.

Safety of high-power short pulse single spot diode laser stapedotomy: an experimental animal study

Background We present a new method of diode laser stapedoplasty – high-power short-pulse mode with preliminary carbonization of the waveguide and a single spot of laser ablation. Aims/objective The aim of our research is the safety evaluation of presented mode 0.98 µm diode laser cochleostomy in guinea pigs. Material and methods Guinea pigs (n = 10) received 0.98 µm diode laser cochleostomy on one ear under general anesthesia. The control group was based on untreated ears (n = 10). The assessment of auditory function was performed using the distortion product otoacoustic emission (DPOAE) before and 7 d after surgery. To assess the degree of damage from the laser cochleas were extracted for histological examination. Results To evaluate the negative impact of laser energy on OHCs and auditory function, we analyzed DPOAE amplitudes for 6400 and 8000 Hz since high frequency. The paired Student’s t-test showed no statistically significant difference between the two groups. The histological examination yielded no statistically significant difference in the number of intact OHCs in the two groups. Conclusion and significance Our study confirms that the proposed method of high-power short pulse diode laser stapedotomy is safe for the inner ear. Further prospective and randomized clinical trials are required to evaluate the possible benefits of this method.

Systemic toll-like receptor 9 agonist CpG oligodeoxynucleotides exacerbates aminoglycoside ototoxicity

The Toll-like receptor (TLR) signaling pathway is the key regulator of the innate immune system in response to systemic infection. Several studies have reported that the systemic TLR4 agonist lipopolysaccharide exacerbates aminoglycoside ototoxicity, but the influence of virus-associated TLR7 and TLR9 signaling cascades on the cochlea is unclear. The present study aimed to investigate the auditory effects of systemic TLR7 and TLR9 agonists during chronic kanamycin treatment. CBA/CaJ mice received the TLR7 agonist gardiquimod or TLR9 agonist CpG oligodeoxynucleotides (ODN) one day before kanamycin injection and on the 5th and 10th days during a 14-day course of kanamycin treatment. We observed that systemic gardiquimod or CpG ODN alone did not affect the baseline auditory brainstem response (ABR) threshold. Three weeks after kanamycin treatment, gardiquimod did not significantly change ABR threshold shifts, whereas CpG ODN significantly increased kanamycin-induced ABR threshold shifts. Furthermore, outer hair cell (OHC) evaluation revealed that CpG ODN reduced distortion product otoacoustic emission amplitudes and increased kanamycin-induced OHC loss. CpG ODN significantly elevated cochlear Irf-7, Tnf-α, Il-1, and Il-6 transcript levels. In addition, an increased number of Iba-1+ cells, which represented activated macrophages, was observed in the cochlea treated with CpG ODN. Our results indicated that systemic CpG ODN exacerbated kanamycin-induced ototoxicity and increased cochlear inflammation. This study implies that patients with underlying virus infection may experience more severe aminoglycoside-induced hearing loss if it occurs.

Does 3 Tesla Magnetic Resonance Imaging Have Adverse Effect on Cochlear Functions?

Objective: The aim of this study was to investigate the effects of 3 Tesla (3T) magnetic resonance imaging (MRI) noise on cochlear functions.Methods: The distortion product otoacoustic emission (DPOAE) test was applied to patients who were scheduled to have 3T MRI in the tertiary care center. Patients who revealed emission amplitudes at all frequencies (1, 1.5, 2, 3, 4, 6, and 8 kHz) in the DPOAE test before MRI were included in the study. After MRI, the DPOAE test was performed twice on 17 patients (33 ears) (immediately after MRI and 30 minutes after MRI). The changes in the results of the tests taken before MRI (pre-MRI), immediately after MRI (post-MRI 1), and at 30 minutes after MRI (post-MRI 2) in the DPOAE amplitudes at all frequencies were compared statistically.Results: There was a significant difference between pre-MRI, post-MRI 1, and post-MRI 2 measurements at 3, 6, and 8 kHz. In pairwise comparisons; post-MRI 1 was statistically lower than post-MRI 2 at 3 kHz, and post-MRI 1 was statistically lower than pre-MRI and post-MRI 2 at 6 and 8 kHz. In addition, post-MRI 2 was significantly lower than pre-MRI at 8 kHz.Conclusion: According to these results, 3T MRI noise does not have any permanent negative impact on hearing functions. It can only cause DPOAE amplitude changes at high frequencies. This is a clinically negligible effect. Therefore, it can be considered that the 3T MRI examination with protective headphones does not cause any adverse side effects in terms of hearing functions.

Inner hair cell dysfunction in Klhl18 mutant mice leads to low frequency progressive hearing loss.

Age-related hearing loss in humans (presbycusis) typically involves impairment of high frequency sensitivity before becoming progressively more severe at lower frequencies. Pathologies initially affecting lower frequency regions of hearing are less common. Here we describe a progressive, predominantly low-frequency recessive hearing impairment in two mutant mouse lines carrying different mutant alleles of the Klhl18 gene: a spontaneous missense mutation (Klhl18lowf) and a targeted mutation (Klhl18tm1a(KOMP)Wtsi). Both males and females were studied, and the two mutant lines showed similar phenotypes. Threshold for auditory brainstem responses (ABR; a measure of auditory nerve and brainstem neural activity) were normal at 3 weeks old but showed progressive increases from 4 weeks onwards. In contrast, distortion product otoacoustic emission (DPOAE) sensitivity and amplitudes (a reflection of cochlear outer hair cell function) remained normal in mutants. Electrophysiological recordings from the round window of Klhl18lowf mutants at 6 weeks old revealed 1) raised compound action potential thresholds that were similar to ABR thresholds, 2) cochlear microphonic potentials that were normal compared with wildtype and heterozygous control mice and 3) summating potentials that were reduced in amplitude compared to control mice. Scanning electron microscopy showed that Klhl18lowf mutant mice had abnormally tapering of the tips of inner hair cell stereocilia in the apical half of the cochlea while their synapses appeared normal. These results suggest that Klhl18 is necessary to maintain inner hair cell stereocilia and normal inner hair cell function at low frequencies.

Distortion Product Otoacoustic Emissions (DPOAE) patterns in individuals with Type 1 and Type 2 Diabetes Mellitus - A comparative study

Diabetes mellitus (DM) is a chronic and potentially life-threatening condition, incidence of which is increasing rapidly in the present era. Various studies showed conflicting relationship between DM and Hearing Loss (HL). The current study was carried out to find the effect of Type 1 and Type 2 DM on hearing. The study group consisted of 90 adults in the age range of 20 to 40 years from various hospitals in and around Calicut, Kerala. These participants were divided into three groups: Group1 (Experimental group 1), included 30 individuals with Type 1 DM; Group 2 (Experimental group 2), included 30 individuals with Type 2 DM and Group 3 (Control group) included 30 age-matched non-diabetic individuals with normal hearing sensitivity. Results of the study revealed that there was significant difference in the DPOAE amplitude between Type 1 and Type 2 DM with control group and there was no significant difference in the DPOAE amplitude between Type 1 and Type 2 DM group. From the results it can be concluded that DPOAE amplitude were reduced in both Type 1 and Type 2 DM when compared to control group. This could be attributed to damage of the cochlear Outer Hair Cells (OHCs). Further, it could be assumed that damage to the OHCs due to DM in both Type 1 and Type 2 groups are relatively equal.

Peripheral Auditory Function in Young HIV-Positive Adults With Clinically Normal Hearing.

Little is known about peripheral auditory function in young adults with HIV, who might be expected to show early evidence of hearing loss if HIV infection or treatment does affect peripheral function. The goal of this study was to compare peripheral auditory function in 2 age- and gender-matched groups of young adults with clinically normal hearing with and without HIV. Matched cohort study with repeated measures. Infectious disease center in Dar es Salaam, Tanzania. Participants included HIV-positive (n = 38) and HIV-negative (n = 38) adults aged 20 to 30 years who had clinically normal hearing, defined as type A tympanograms, air conduction thresholds ≤25 dB HL bilaterally from 0.5 to 8 kHz, and distortion product otoacoustic emissions (DPOAEs) >6 dB above the noise floor bilaterally from 1.5 to 8 kHz. Participants were tested multiple times over 6-month intervals (average, 2.7 sessions/participant) for a total of 208 observations. Primary outcome measures included tympanograms, air conduction audiograms, DPOAEs, and click-evoked auditory brainstem responses. HIV groups did not significantly differ in age, static immittance, or air conduction thresholds. HIV-positive status was independently associated with approximately 3.7-dB lower DPOAE amplitudes from 2 to 8 kHz (95% CI, 1.01-6.82) in both ears and 0.04-µV lower (95% CI, 0.003-0.076) auditory brainstem response wave I amplitudes in the right ear. Young adults living with HIV have slightly but reliably smaller DPOAEs and auditory brainstem response wave I amplitudes than matched HIV-negative controls. The magnitude of these differences is small, but these results support measuring peripheral auditory function in HIV-positive individuals as they age.

Reliability of Contralateral Suppression in Evoked Distortion Product Otoacoustic Emissions.

Introduction Distortion product otoacoustic emissions (DPOAE) and their suppression may be considered useful in monitoring cochlear function and the efferent auditory pathway inhibitory effect. Nonetheless, the establishment of reliable parameters of response variations is of great importance. Objectives To verify the replicability of test and retest in the research of the inhibitory effect of the efferent pathway using contralateral suppressing stimulus during DPOAE recording for clinical applicability. Methods Cross-sectional study with 48 volunteers, aged 18 to 30 years, with normal audiometric thresholds. The procedures included were audiometric and immittance measures to overrule any conductive or sensorineural conditions and DPOAE recordings without and with contralateral suppression with a 60 dBHL white noise. Distortion product otoacoustic emissions amplitudes were analyzed and compared in both conditions with Wilcoxon test, and the Spearman correlation test was used to assess test-retest reliability. Results The comparative analysis showed differences between amplitudes in test and retest conditions only in 1,500 Hz for DPOAE measures with all other tested frequencies showing no differences, and no difference was observed in all recorded frequencies in the test and retest comparison for DPOAE suppression. The degree of correlation between test and retest of DPOAE amplitude was good at 6,000 Hz and strong (r > 0.880) at the other frequencies. For DPOAE with suppression, all frequencies presented strong correlation between test and retest: 1,500 Hz (r = 0.880), 2,000 Hz (r = 0.882), 3,000 Hz (r = 0.940), and 6,000 Hz (r = 0.957). Conclusions The study found good replicability in contralateral suppression of DPOAE with potential clinical applicability, and we recommend conducting the test from 2000Hz to higher frequencies for more reliable results.