Hearing Threshold Levels Research Articles

Magnetic stem cell targeting to the inner ear

Severe sensorineural deafness is often accompanied by a loss of auditory neurons in addition to injury of the cochlear epithelium and hair cell loss. Cochlear implant function however depends on a healthy complement of neurons and their preservation is vital in achieving optimal results. We have developed a technique to target mesenchymal stem cells (MSCs) to a deafened rat cochlea. We then assessed the neuroprotective effect of systematically delivered MSCs on the survival and function of spiral ganglion neurons (SGNs). MSCs were labeled with superparamagnetic nanoparticles, injected via the systemic circulation, and targeted using a magnetized cochlea implant and external magnet. Neurotrophic factor concentrations, survival of SGNs, and auditory function were assessed at 1week and 4weeks after treatments and compared against multiple control groups. Significant numbers of magnetically targeted MSCs (>30MSCs/section) were present in the cochlea with accompanied elevation of brain-derived neurotrophic factor and glial cell-derived neurotrophic factor levels (p<0.001). In addition we saw improved survival of SGNs (approximately 80% survival at 4weeks). Hearing threshold levels in magnetically targeted rats were found to be significantly better than those of control rats (p<0.05). These results indicate that magnetic targeting of MSCs to the cochlea can be accomplished with a magnetized cochlear permalloy implant and an external magnet. The targeted stem cells release neurotrophic factors which results in improved SGN survival and hearing recovery. Combining magnetic cell-based therapy and cochlear implantation may improve cochlear implant function in treating deafness.

The Hearing Threshold of Employees Exposed to Noise Generated by the Low-Frequency Ultrasonic Welding Devices

Abstract The aim of the study was to assess the hearing threshold levels (HTLs) in employees exposed to noise generated by low-frequency ultrasonic technological equipment in comparison with the HTLs of workers exposed to audible noise at the similar A-weighted equivalent-continuous sound pressure level. The study includes measurements of ultrasonic and audible noise at workplaces and hearing tests, i.e. conventional pure-tone audiometry and extended high-frequency audiometry. The study group comprised 90 workers, aged 41.4±10.0 years (mean±SD), exposed for 17.3±9.8 years to noise generated by ultrasonic devices at mean daily noise exposure level (‹LEX,8h›) of 80.6±2.9 dB. The reference group consists of 156 subjects, exposed to industrial noise (without ultrasonic components) at similar A-weighted equivalent-continuous sound pressure level (‹LEX,8h› = 81.8±2.7 dB), adjusted according to age (39.8±7.7 years), gender and job seniority (14.0±7.0 years). This group was selected from database collected in the Nofer Institute of Occupational Medicine. Audiometric hearing threshold levels in the frequency range of 0.5-6 kHz were similar in both groups, but in the frequency range of 8-12.5 kHz they were higher in the group of employees exposed to ultrasonic noise. The findings suggest that differences in the hearing threshold (at high frequencies) in analyzed groups may be due to differences in spectral composition of noise and show the need to continue the undertaken studies.

Hearing loss associated with repeated MRI acquisition procedure-related acoustic noise exposure: an occupational cohort study

ObjectiveTo study the effects of repeated exposure to MRI-related acoustic noise during image acquisition procedures (scans) on hearing.MethodsA retrospective occupational cohort study was performed among workers of an MRI manufacturing...

Audiograms and hearing loss before and after cisplatin-based chemotherapy (CBCT) in testicular cancer survivors (TCS).

e16047 Background: 80% of TCS were reported to have a hearing loss based on post-CBCT audiograms (American Speech-Language-Hearing Association (ASHA) definition; Frisina et al, JCO 2016:34) Methods: 46 TCS treated with CBCT 1980-1994 with audiograms (0.25-8 kHz) pre chemotherapy (PRE) and at a survey (SURV) after median 10 years were included (cases). Audiograms at SURV from 46 age-matched TCS without CBCT were included as controls. Linear regression was performed to evaluate predictors for change in hearing threshold level (HTL) from PRE to SURV. Mean HTL for both ears exceeding 20 dB at any frequency 0.25-8 kHz were classified as a hearing loss (ASHA definition). We also applied the WHO definition of hearing loss, present if the average HTL threshold for the four frequencies 0.5, 1, 2 and 4 kHz exceeded 20 dB (M4 definition). At SURV, self-reported hearing loss was assessed by a questionnaire (categorized as “a little”, “quite a bit” and “very much” vs. “not at all”). Results: Age and PRE HTL was associated with change in HTL for most frequencies. Cisplatin dose was significantly associated with change in HTL for the frequencies 2 to 8 kHz, with a gradually greater change in HTL and lower p-value with increasing frequencies. For the 8 kHz frequency, each 100 mg increase in cumulative cisplatin dose was associated with a deterioration of 3.6 dB (p &lt; .001). According to ASHA, the prevalence of a hearing loss among cases was 33% PRE, 70% at SURV, and 65% among controls at SURV (cases vs. controls, p = .66). According to M4, the prevalence of hearing loss among cases was 6.5% PRE, 13% at SURV, and 2.2% among controls at SURV (cases vs. controls, p = 0.05). Overall 29% of cases, and 33% of controls (p = .70) reported some degree of hearing impairment at SURV, of whom only 6.5% of cases reported more than “a little”. Self-reported hearing loss was not associated with hearing loss according to ASHA (p = .20), but was associated with the M4 definition (p = .02). Conclusions: Cisplatin is associated with a moderate hearing loss particularly at higher frequencies. Ageing is important for hearing loss regardless of treatment. The ASHA definition of hearing loss overestimates the hearing problem and should not be used as a clinical tool.

Loudness and annoyance of disturbing sounds – perception by normal hearing subjects

Objective: Sounds in the daily environment may cause loudness and annoyance. The present study investigated the perception of loudness and annoyance for eight different sounds present in a daily sound environment and at nine different levels varying by ±20 dB around the recorded level. The outcomes were related to tests of participants’ auditory and cognitive abilities. Design: The participants undertook auditory and working memory (WM) tests prior to ratings of everyday sounds previously shown to be disturbing for persons with hearing impairment (hearing aid users). Study sample: Twenty-one participants aged between 24 and 71 years, with normal hearing threshold levels. Results: Both perceived loudness and annoyance were primarily driven by the sound level. Sounds emitted from paper were rated as having greater loudness and being more annoying than the other sound sources at the same sound level. Auditory and cognitive abilities did not influence the perception of loudness and annoyance. Conclusions: Loudness and annoyance ratings were mainly driven by sound level. Expectations of a sound seemed to influence the assessment of loudness and annoyance while auditory performance and WM capacity showed no influence on the ratings.

Transient evoked otoacoustic emissions in rock musicians

Objective: Our focus in this study was the assessment of transient evoked otoacoustic emissions (TEOAEs) in a large group of rock musicians. A further objective was to analyse tinnitus among rock musicians as related to TEOAEs. Design: The study was a cross-sectional survey of rock musicians selected at random. A control group was included at random for comparison. Study sample: We recruited 111 musicians and a control group of 40 non-musicians. Testing was conducted by using clinical examination, pure tone audiometry, TEOAEs and a questionnaire. Results: TEOAE SNR in the half-octave frequency band centred on 4 kHz was significantly lower bilaterally in musicians than controls. This effect was strongly predicted by age and pure-tone hearing threshold levels in the 3–6 kHz range. Bilateral hearing thresholds were significantly higher at 6 kHz in musicians. Twenty percent of the musicians had permanent tinnitus. There was no association between the TEOAE parameters and permanent tinnitus. Conclusions: Our results suggest an incipient hearing loss at 6 kHz in rock musicians. Loss of TEOAE SNR in the 4 kHz half-octave frequency band was observed, but it was related to higher mean 3–6 kHz hearing thresholds and age. A large proportion of rock musicians have permanent tinnitus.

An assessment of the permissible exposure limit for industrial complex noise exposure

An 8-hr time-weighted average exposure of 85 dBA was adopted as the permissible exposure limit (PEL) by most current international standards for exposure to noise. Using the definition of material hearing impairment (MHI) as the average of hearing threshold levels for both ears exceeded 25 dB at 1, 2, 3, and 4 kHz, NIOSH estimated that the excess risk was 8% for workers exposed to an average noise level of 85 dBA over a 40-year working lifetime. However, this 85 dBA PEL was based on the data that was acquired from workers exposed to steady state (Gaussian) noises. In this study a database of 648 workers (age 36.9 yrs + /- 7.8, exposure duration 12.8 yrs + /- 8.0) exposed to non-Gaussian noises were used to assess the 85 dBA PEL. Among them 222 subjects exposed to noise at level of 80-84 dBA and 426 subjects at 85-89 dBA. Although the average duration of exposure from non-Gaussian database was much less than 40 years, the prevalence of MHI was 16.7% at level of 80-84 dBA and 31.5% at level of 84-89 dBA. The results show that 85 dBA PEL may not well protect hearing for workers exposed to non-Gaussian complex noise exposure.

Effects of Occupational Noise Exposure on Blood Pressure and other Aspects of Health for Workers in Selected Industrial Places in Zakho City, Iraq

Industrial or Occupational noise play a vital role in the life of workers. This source of pollution disrupts and annoys the daily activities of workers. Occupational Noise pollution is increasingly being recognized as a physical factor in the environment that is injurious to many aspects of health. This study focuses on the industrial noise and its effects on workers. The aim of the study is to find out the possible relation between the occupational noise exposure and arterial blood pressure, pulse rate, and hearing thresholds for workers at several industrial areas in Zakho City, Kurdistan region of Iraq. The study group included 113 workers employed in twenty-one different factories (chosen randomly). All the individuals under study were men. Their ages were between 15 to 60 years. The noise level was between (76.5-98) decibels (dB(A)). In order to observe the harmful effects of the noise, a questionnaire was made for all the workers. The systolic blood pressure mean for the samples is increased by 6.07 mmHg, while the diastolic blood pressure mean is increased by 2.63 mmHg; the pulse rate mean is increased by 5.56 beats/minute. The hearing threshold levels also show a decrease in their values.

Unilateral Hearing Loss: Understanding Speech Recognition and Localization Variability-Implications for Cochlear Implant Candidacy.

At a minimum, unilateral hearing loss (UHL) impairs sound localization ability and understanding speech in noisy environments, particularly if the loss is severe to profound. Accompanying the numerous negative consequences of UHL is considerable unexplained individual variability in the magnitude of its effects. Identification of covariables that affect outcome and contribute to variability in UHLs could augment counseling, treatment options, and rehabilitation. Cochlear implantation as a treatment for UHL is on the rise yet little is known about factors that could impact performance or whether there is a group at risk for poor cochlear implant outcomes when hearing is near-normal in one ear. The overall goal of our research is to investigate the range and source of variability in speech recognition in noise and localization among individuals with severe to profound UHL and thereby help determine factors relevant to decisions regarding cochlear implantation in this population. The present study evaluated adults with severe to profound UHL and adults with bilateral normal hearing. Measures included adaptive sentence understanding in diffuse restaurant noise, localization, roving-source speech recognition (words from 1 of 15 speakers in a 140° arc), and an adaptive speech-reception threshold psychoacoustic task with varied noise types and noise-source locations. There were three age-sex-matched groups: UHL (severe to profound hearing loss in one ear and normal hearing in the contralateral ear), normal hearing listening bilaterally, and normal hearing listening unilaterally. Although the normal-hearing-bilateral group scored significantly better and had less performance variability than UHLs on all measures, some UHL participants scored within the range of the normal-hearing-bilateral group on all measures. The normal-hearing participants listening unilaterally had better monosyllabic word understanding than UHLs for words presented on the blocked/deaf side but not the open/hearing side. In contrast, UHLs localized better than the normal-hearing unilateral listeners for stimuli on the open/hearing side but not the blocked/deaf side. This suggests that UHLs had learned strategies for improved localization on the side of the intact ear. The UHL and unilateral normal-hearing participant groups were not significantly different for speech in noise measures. UHL participants with childhood rather than recent hearing loss onset localized significantly better; however, these two groups did not differ for speech recognition in noise. Age at onset in UHL adults appears to affect localization ability differently than understanding speech in noise. Hearing thresholds were significantly correlated with speech recognition for UHL participants but not the other two groups. Auditory abilities of UHLs varied widely and could be explained only in part by hearing threshold levels. Age at onset and length of hearing loss influenced performance on some, but not all measures. Results support the need for a revised and diverse set of clinical measures, including sound localization, understanding speech in varied environments, and careful consideration of functional abilities as individuals with severe to profound UHL are being considered potential cochlear implant candidates.

Prevalence of Hearing Loss and Hearing Impairment among Small and Medium Enterprise Workers in Selangor, Malaysia

Factories and Machinery (Noise Exposure) Regulation 1989 has always demanded employer to protect workers from noise exposure ≥85 dB. However, noise induced hearing loss (NIHL) has been the highest notifiable occupational health issue among Malaysian workers in 2014. A cross-sectional study aimed to investigate the prevalence of hearing loss (HL) among 146 adult manufacturing workers with noise exposure ≥85 dB was carried out in Selangor. Pure tone audiometry and a validated questionnaire were used to determine the hearing status and information of the respondents. The results showed that the prevalence of HL was 73.3% and the prevalence of hearing impairment was 23.3%. Male workers (63.0%) had higher prevalence of HL than female workers (36.4%). Mean hearing threshold levels of HL respondents were significantly higher than respondents with normal hearing. It was discovered that among workers with employment of more than 10 years, > 80% of them suffered from HL. Association between employment years and hearing condition (normal, non-bilateral and bilateral HL) was statistically significant, χ(4)= 10.51, p=0.033, with Kendall tau-c correlation showing positive and weak (p=0.18) association. Highest HL cases were found at 4 and 6 kHz. World Health Organisation and Factories and Machinery (Noise Exposure) Regulation 1989 classification on degree of hearing impairment showed slight to moderate hearing impairment among the respondents and both standards did not differ much (8.9% vs 6.9%, respectively). As a conclusion, prevalence of hearing loss and hearing impairment among manufacturing workers were high. Age, male sex, monthly salary and employment years were possible influencing factors.

Reference equivalent threshold sound pressure levels for Apple EarPods.

Reference equivalent threshold sound pressure levels (RETSPLs) are used when calibrating audiometric equipment to a hearing threshold level of zero at various frequencies. To the best of the authors' knowledge, the RETSPLs for Apple EarPods (MB770G) have not been reported, and so this study aimed to measure them. The hearing thresholds of 36 normal-hearing subjects (72 ears) were measured at 250, 500, 1000, 2000, 4000, and 8000 Hz, with the measurements being performed twice in 33 subjects (66 ears) for evaluating the test-retest reliability. This study provides Apple EarPod RETSPLs and shows significant Pearson's correlations (p < 0.001) with no significant Wilcoxon signed-rank test differences (p > 0.01), which confirm the test reliability.

The Effect of Limited Counseling Time on Hearing Aid Uptake

Background and Objectives To determine appropriate counseling time for the first hearing aids user, we measured the effectiveness of first counseling time limit of 20 minutes for those who need hearing aids and collected predictive parameters during history taking. Subjects and Method We reviewed the medical records of 956 patients (age 66.5±12.1) with hearing impairment who needed hearing aids. We divided patients into two groups, those who had counseling time limited to 20 minutes and others who had no time limitation. Job status, working condition of noise status, social activity and audiological variables were analyzed as probable predicting factors influencing the purchasing of the hearing aid (penetration rate). Results Of the total 956 patients, 48.64% of subjects decided to purchase hearing aids at first counseling. The two groups showed no significant difference (p=0.396): 49.81% of the group without time limitation purchased the hearing aid and 47.04% of those with time limitation purchased the aid. The social status, right side pure tone threshold and right side tinnitus were significant for calculating the explanation power (64.15%) in the hearing aid uptake probability equation. Conclusion The level of social activity, hearing threshold and tinnitus were predictive variables obtained during the counseling. The time limitation of 20 minutes did not affect the rate of decision to purchase hearing aids. These results might help hearing clinics improve efficient time management at hearing aid clinics. Key words: Counseling ㆍ Hearing aids

Exposure to excessive sounds and hearing status in academic classical music students.

The aim of this study was to assess hearing of music students in relation to their exposure to excessive sounds. Standard pure-tone audiometry (PTA) was performed in 168 music students, aged 22.5±2.5 years. The control group included 67 subjects, non-music students and non-musicians, aged 22.8±3.3 years. Data on the study subjects' musical experience, instruments in use, time of weekly practice and additional risk factors for noise-induced hearing loss (NIHL) were identified by means of a questionnaire survey. Sound pressure levels produced by various groups of instruments during solo and group playing were also measured and analyzed. The music students' audiometric hearing threshold levels (HTLs) were compared with the theoretical predictions calculated according to the International Organization for Standardization standard ISO 1999:2013. It was estimated that the music students were exposed for 27.1±14.3 h/week to sounds at the A-weighted equivalent-continuous sound pressure level of 89.9±6.0 dB. There were no significant differences in HTLs between the music students and the control group in the frequency range of 4000-8000 Hz. Furthermore, in each group HTLs in the frequency range 1000-8000 Hz did not exceed 20 dB HL in 83% of the examined ears. Nevertheless, high frequency notched audiograms typical of the noise-induced hearing loss were found in 13.4% and 9% of the musicians and non-musicians, respectively. The odds ratio (OR) of notching in the music students increased significantly along with higher sound pressure levels (OR = 1.07, 95% confidence interval (CI): 1.014-1.13, p < 0.05). The students' HTLs were worse (higher) than those of a highly screened non-noise-exposed population. Moreover, their hearing loss was less severe than that expected from sound exposure for frequencies of 3000 Hz and 4000 Hz, and it was more severe in the case of frequency of 6000 Hz. The results confirm the need for further studies and development of a hearing conservation program for music students. Int J Occup Med Environ Health 2017;30(1):55-75.

청각선별을 통과한 주간 보호와 언어재활 서비스 수혜 소아의 가청역치

청각선별에서 반응 역치는 검사 환경 잡음, 청각기관 생리적 특성, 과도한 음원 노출 등에 따라 다르게 나타난다. 이 연구 목적은 청각선별을 통과한 소아의 주파수별 가청역치에 대한 정보를 획득하는데 있다. 연구 대상은 언어치료센터와 지역아동센터에 다니는 3.3세부터 16.3세(<TEX>$9.01{\pm}2.52$</TEX>) 사이의 110명으로 하였고, 이들의 소아 청각 선별 결과를 후향적으로 분석하였다. 청각선별은 고막운동성계측(Tympanometry), 등골근반사(acoustic reflex threshold), 자동화 이음향방사(automated otoacoustic emission), 순음청각선별(pure tone screening)을 시행하였다. 대상자들은 모두 청각선별 정상 기준에 포함되었다. 주파수별 가청역치 차이는 반복측정 분산분석 하였다. 결과: 가청역치 평균은 500, 1,000, 2,000, 4,000 Hz의 순서로 우측 귀 <TEX>$16{\pm}6.49$</TEX>, <TEX>$11.5{\pm}4.79$</TEX>, <TEX>$6.86{\pm}4.99$</TEX>, <TEX>$5.95{\pm}6.65$</TEX> dB HL, 좌측 귀 <TEX>$15.68{\pm}6.01$</TEX>, <TEX>$9.95{\pm}5.24$</TEX>, <TEX>$5.72{\pm}5.21$</TEX>, <TEX>$5.63{\pm}7.04$</TEX> dB HL로 각각 관찰되었다. 주파수 사이에는 500Hz와 1,000, 2,000, 4,000 Hz(p=.000), 1,000과 2,000, 4,000 Hz(p=.000)로 유의한 차이가 있었다. Responded threshold level in hearing screening depends on the noise level of test surroundings, physiological characteristics of hearing organs, excessive sound source exposures, and so on. The purpose of this study is to obtain the basic information of hearing threshold level at each frequencies in children with passed hearing screening. Subjects were 110 children, aged were from 3.3 to 16.3 (<TEX>$9.01{\pm}2.52$</TEX>), who were at private speech language pathological clinics and daycare centers. Methods of Hearing screening were tympanometry, acoustic reflex threshold, automated otoacoustic emission, and pure tone screening. The subjects were in normal criteria of hearing screening. The differences of hearing threshold among ages and frequencies were measured by means of repeated measures ANOVA. The mean of hearing thresholds level was observed <TEX>$16{\pm}6.49$</TEX>, <TEX>$11.5{\pm}4.79$</TEX>, <TEX>$6.86{\pm}4.99$</TEX>, <TEX>$5.95{\pm}6.65$</TEX> dB HL in the right ear and <TEX>$15.68{\pm}6.01$</TEX>, <TEX>$9.95{\pm}5.24$</TEX>, <TEX>$5.72{\pm}5.21$</TEX>, <TEX>$5.63{\pm}7.04$</TEX> dB HL in the left ear, in frequency of 500, 1,000, 2,000, 4,000 Hz respectively. There was a significant difference between 500 and 1,000, 2,000, 4,000 Hz (p=.000), between 1,000 and 2,000, 4,000 Hz (p=.000).

Early acoustic evoked potentials in patients with "small" vestibular schwannomas

The prognostic potential of click-evoked early acoustic evoked potentials (EAEP) for vestibular schwannoma (VS) diagnostics is considered insufficient for tumors small than approximately <1.5cm in diameter. However, up until now, the derivations at higher sound pressure levels have mainly been used for EAEP evaluation. The aim of this study was to examine whether registered EAEP are more sensitive to pathological changes at low sound pressure levels and with smaller tumors. Comparative examinations (pair-matched) were conducted with 34patients. An appropriate patient with an identical hearing level threshold - either apurely cochlear hearing deficiency or anormal hearing level - was matched to each tumor patient. EAEP were registered at 80, 60,and 40dBHL. The characteristic parameters where assessed visually and evaluated statistically, both in respect to patient groups and in bilateral comparisons. Furthermore, the relationship between the level-dependent waveV latency differences in bilateral comparison and tumor size were evaluated. Low-level cochlear hearing deficiencies did not cause achange in waveV latency, such that the pathological side differences at 40dBHL in patients with VS can be considered a"purely" retrocochlear hearing deficiency. The sensitivity of EAEP registered at 40dBHL decreases only with tumors under about <5mm in diameter. Combining the values of waveV latency and interaural waveV latency difference effectively reduces false-positive findings at 40dBHL to zero. Beyond the suprathreshold derivations, potential registrations at 40dBHL can also be diagnostically useful to differentiate cochlear from retrocochlear lesions. In the case of small VS and good hearing levels, these registrations may also be used for intraoperative monitoring to allow better evaluation of level-dependent changes in the auditory nerve.

Tinnitus and leisure noise

Objective: To study the relationship of life-time noise exposure and experience of tinnitus. Design: Audiometric measures included otoscopy, pure tone air- and bone-conduction hearing threshold levels (HTL) and otoacoustic emissions (OAEs). Participants completed questionnaires including demographic information, past hearing health, history of participation in loud leisure activities, and attitudes to noise. Study sample: A representative sample (1435) of the young (11–35 years old) Australian population. Results: Of the sample, 63% indicated they experienced tinnitus in some form. There was no correlation of tinnitus experience with HTL or OAE amplitudes. Although median octave band HTLs for those who experienced tinnitus “all the time” were slightly higher for those who did not, neither group exhibited HTLs outside clinically-normal values. Of those who experienced tinnitus a direct correlation was found between frequency of experience of tinnitus and increasing cumulative, life-time noise exposure. Those who experienced tinnitus were more likely to report noticing deterioration in their hearing ability over time and to report difficulty hearing in quiet and/or noisy situations. Conclusions: Experience of tinnitus was found throughout this young population but not associated with HTLs or variation in OAE amplitudes. Males experienced ‘permanent’ tinnitus at significantly greater rate than females.

Frequency characteristics of neuromagnetic auditory steady-state responses at the supra-threshold level

Auditory steady-state response (ASSR) is a neuronal electrical component recorded as a continuous sinusoidal signal phase-locked to a modulation frequency of sounds. Since ASSR amplitude shows high correlation with perceptual characteristics at hearing threshold level, the ASSR has been examined as a candidate for an objective index of the human hearing ability per frequency. However, the relationship between ASSR and perception at the supra-threshold level has not been clarified. In this study, characteristics of ASSR magnitude relative to loudness at the supra-threshold level were investigated. Neuromagnetic 40-Hz ASSR was recorded in response to sinusoidally amplitude-modulated sweep tones with carrier frequency covering the frequency range of 0.1-12.5 kHz. Sound intensity was equalized at 50-, 60-, and 70-dB SPL with an accuracy of ±0.5-dB SPL at the phasic peak of the modulation frequency. Corresponding loudness characteristics were modeled by substituting the detected individual hearing thresholds into a standard formula (ISO226:2003(E)). The strength of the ASSR component was maximum at 0.5 kHz, and it decreased linearly on logarithmic scale toward lower and higher frequencies, whereas loudness model was plateaued between 0.5 and 4 kHz. The results indicated that frequency characteristics of the ASSR were not equivalent to those of SPL and loudness model.

Protective Effect of Selenium Against Cisplatin-Induced Ototoxicity in an Experimental Design.

Cisplatin is an effective chemotherapeutic agent in the treatment of several types of malignant solid tumors but its clinical use is associated with ototoxicity. In the present study, we investigated the effect of selenium administration on lipid peroxidation (malondialdehyde [MDA]) and cisplatin-induced ototoxicity in rats. Healthy wistar albino rats (n = 21) were randomly divided into 3 groups: control (C), cisplatin (Cis), cisplatin and selenium (Cis+Se). Cisplatin was administered for 3 days to Cis and Cis+Se groups. Cis+Se group received selenium 5 days before cisplatin injection and continued for 11 consecutive days. Hearing thresholds and lipid peroxidation (MDA) levels of the rats were recorded before injections and at the end of experimental protocol. The cochleas of animals were harvested for histologic and immunuhistochemical examinations. In biochemichal analyses, pretreatment with selenium prevented the elevation of MDA levels in Cis+Se group rats. Moreover, animals in Cis+Se group had better hearing threshold levels than animals in cis group. Samples obtained from the animals in Cis group revealed extensive loss of the normal microarchitecture of the organ of Corti. On the other hand, animals in Cis+Se group exhibited a preservation of the morphology of the organ of Corti and outer hair cells. In the immunohistochemical examinations of cochlear tissues stained with anti-caspase-3, a higher degree of immunopositivity was found in the Cis group. When Cis+Se group and Cis group were compared, significantly less immunopositivity occurred in the Cis+Se group (P < 0.05). Thus, it appears that pretreatment with selenium may reduce cisplatin-induced ototoxicity in rats.

Vestibular schwannoma diagnosis: evaluation of a neuro-otological test battery

Objective: Gadolinium-enhanced Magnetic Resonance Imaging (MRI) constitutes the gold standard technique in detecting vestibular schwannomas (VS). The investigation aimed to verify whether it is possible to reach high sensitivity in the early diagnosis of VS, combining Auditory Brainstem Responses (ABRs) with other bedside and electrophysiological neuro-otological tests.Methods: Fifty-five patients suffering from VS smaller than 2 cm in major diameter, detected by gadolinium-enhanced MRI, were submitted to: Pure Tone Audiometry, Speech Audiometry, Vestibular Examination, Caloric Test, Head Shaking Test (HST), Head Impulse Test (HIT), Hyperventilation Test (HT), Vibration Test (VT), ABRs, Cervical Vestibular Evoked Myogenic Potentials (cVEMPs).Results: HST showed pathological results in 34 cases (61.82% sensitivity), HIT in 29 (52.73% sensitivity), HT in 38 (69.09% sensitivity), VT in 27 (49.1% sensitivity), ABRs in 35 (in 12 cases this examination was not conducted because of the high pure tone hearing threshold level, 81.39% sensitivity), cVEMPs in 34 (61.82% sensitivity). If we consider only symptomatic patients (54 out of 55), in all cases we observed at least one pathological test (100% sensitivity).Conclusion: In patients suffering from unilateral or asymmetrical sensorineural hearing loss, we suggest the use of bedside and electrophysiological tests in order to reduce the use of imaging to high suspicion cases of retrocochlear disease, lowering costs and waiting lists.

An Estimation of the Whole-of-Life Noise Exposure of Adolescent and Young Adult Australians with Hearing Impairment.

Since amplified music gained widespread popularity, there has been community concern that leisure-noise exposure may cause hearing loss in adolescents and young adults who would otherwise be free from hearing impairment. Repeated exposure to personal stereo players and music events (e.g., nightclubbing, rock concerts, and music festivals) are of particular concern. The same attention has not been paid to leisure-noise exposure risks for young people with hearing impairment (either present from birth or acquired before adulthood). This article reports on the analysis of a subset of data (leisure participation measures) collected during a large, two-phase study of the hearing health, attitudes, and behaviors of 11- to 35-yr-old Australians conducted by the National Acoustic Laboratories (n = 1,667 hearing threshold level datasets analyzed). The overall aim of the two-phase study was to determine whether a relationship between leisure-noise exposure and hearing loss exists. In the current study, the leisure activity profiles and accumulated ("whole-of-life") noise exposures of young people with (1) hearing impairment and (2) with normal hearing were compared. Cross-sectional cohort study. Hearing impaired (HI) group, n = 125; normal (nonimpaired) hearing (NH) group, n = 296, analyzed in two age-based subsets: adolescents (13- to 17-yr-olds) and young adults (18- to 24-yr-olds). Participant survey. The χ² test was used to identify systematic differences between the leisure profiles and exposure estimates of the HI and NH groups. Whole-of-life noise exposure was estimated by adapting techniques described in ISO 1999. For adolescents, leisure profiles were similar for the two groups and few individuals exceeded the stated risk criterion. For young adults, participation was significantly lower for the HI group for 7 out of 18 leisure activities surveyed. Activity diversity and whole-of-life exposure were also significantly lower for the HI group young adults. A substantial number of individuals in both groups reported participation in leisure activities known to involve high noise levels (HI < NH). The individual whole-of-life exposures for the HI and NH participants were estimated and group median exposures were calculated. The median exposure for HI group young adults was significantly lower than that for the NH group (710 versus 1,615 Pa² h [Pascal squared hours]). The number of young adults with estimated exposure above the chosen noise-risk criterion in the NH group is concerning. With respect to the goals of hearing loss prevention initiatives, the more conservative social behavior (e.g., less nightclubbing) observed among HI group young adults may be regarded as a positive finding, but it could also signify relative social disadvantage for some young adults with hearing impairment.