Noise protection with N-acetyl-l-cysteine (NAC) using a variety of noise exposures, NAC doses, and routes of administration

CONCLUSION: These studies extend previous work on N-acetyl-l-cysteine (NAC) and noise, showing protection with NAC against a high-kurtosis noise, showing protection with NAC at low doses, as well as protection by oral gavage. The studies further reveal the potential for the use of NAC in a clinical population exposed to noise. OBJECTIVE: To extend previous work on NAC protection from noise, the current study examined the effectiveness of NAC against a high-kurtosis noise that combined continuous and impact noise, tested the effectiveness of NAC at varying doses, and tested NAC when administered by gavage. MATERIALS AND METHODS: Chinchillas were tested for auditory brainstem responses (ABRs) at five frequencies before and at three time points after one of three noise exposures: high-kurtosis (2 h, 108 dB L(eq)), impulse (75 pairs of 155 dB pSPL impulses), or continuous (4 kHz octave band, 105 dB SPL for 6 h). Animals were treated with NAC or saline vehicle before and after noise. RESULTS: The NAC was protective against the high-kurtosis noise both at low doses and when given orally by gavage.     

Treatment of military acoustic accidents with N-Acetyl-L-cysteine (NAC)

Objective: To study if the antioxidant (AO) N-Acetyl-L-cysteine (NAC) reduces the risk of hearing loss after acoustic accidents in humans.

Design: A retrospective, observational study.

Study sample: Personnel of the Swedish Armed Forces (SAF) exposed to military acoustic accidents during a 5 year period. Included in the study were 221 cases (mean age: 22.9 years). Most of the exposures, 84%, were weapon related. NAC (400?mg) was given directly after the accident in 146 cases; 75 had not received NAC.

Results: The prevalence of hearing thresholds ≥25?dB HL, and the incidence of threshold shifts ≥10?dB, was lower in the NAC group than in the non-NAC group directly after the noise exposure. The deterioration was temporary and not discernable a long time after the accident. The difference was most pronounced in the right ear. The risk reduction to get a temporary hearing loss (TTS), affecting one or both ears was 39% (significant) in the NAC group.

Conclusions: The study has demonstrated a significant reduction of the incidence of TTS by the use of NAC. Since cases of both permanent hearing loss (PTS) and noise-induced tinnitus are recruited from cases with TTS, the demonstrated risk reduction indicates a positive effect of NAC.     

Knowledge,attitudes, behaviors,and noise exposure of baristas

Objective: To examine the daily noise exposure of baristas working in cafés, and to measure their knowledge, attitudes, and behaviors regarding hearing conservation and perceptions of noise in their work environment. Design: Fifteen baristas from six cafés in Portland completed the Knowledge, Attitudes and Behaviors questionnaire, a sound disturbance survey, and a structured interview to document perceptions of noise in the work environment. To measure daily noise exposure, a subset of eight participants wore a personal dosimeter for three different work shifts. Study sample: A total of 11 females and four males, aged between 19 and 36 years old (mean: 26.3, SD: 4.6) recruited from independently owned cafés in the Portland metro area. Results: Dosimetry measurements revealed Leq measurements between 71 and 83 dBA, with noise doses ranging from 4% to 74%, indicating that baristas are not exposed to sound levels above the regulatory criterion. Questionnaire results indicated that baristas have low awareness about the hazards of noise, are not opposed to hearing conservation, and rarely use hearing protection when engaged in noisy activities. Conclusions: Baristas here lacked the pertinent education and motivation to commit to invaluable hearing conservation practices.     

突聋患者血中GSH－PX，SOD和VitE测定

本文对３２例突聋患者进行全血ＧＳＨ－ＰＸ，红细胞ＳＯＤ，血浆ＬＰＯ和ＶｉｔＥ的活性测定，结果具有抗脂质过氧化物作用的ＧＳＨ－ＰＸ和氧自由基特异清除酶ＳＯＤ活性均降低，对细胞有损害作用的ＬＰＯ升高，而ＶｉｔＥ无明显变化。本文从氧自由基反应及氧化还原系统的角度对突聋时的病理生理机制进行探讨。     

Changing beliefs about leisure noise: Using health promotion models to investigate young people's engagement with,and attitudes towards,hearing health

Objective: To investigate factors influencing young people's motivation to reduce their leisure noise exposure, and protect their hearing health. Design: Questionnaires were conducted online to investigate young people's hearing health attitudes and behaviour. Items were developed using an integrated health promotion approach. The stage of change model was used to group participants in relation to their engagement with noise reduction behaviour. The health belief model was used to compare each group's perceptions of susceptibility and severity of hearing loss, as well as the benefits and barriers to noise reduction. Study sample: Results are presented for 1196 young Australians aged between 18 and 35 years. Results: Participants’ engagement with noise reduction behaviour was used to assign them to stage of change groupings: Maintenance (11%), Action (28%), Contemplation (14%), or Pre-contemplation (43%). Each group's responses to health belief model items highlighted key differences across the different stages of engagement. Conclusions: Future hearing health promotion may benefit from tailoring intervention activities to best suit the stage of change of individuals. Different information may be useful at each stage to best support and motivate young people to look after their hearing health.     

Cues for Diotic and Dichotic Detection of a 500-Hz Tone in Noise Vary with Hearing Loss

Hearing in noise is a challenge for all listeners, especially for those with hearing loss. This study compares cues used for detection of a low-frequency tone in noise by older listeners with and without hearing loss to those of younger listeners with normal hearing. Performance varies significantly across different reproducible, or “frozen,” masker waveforms. Analysis of these waveforms allows identification of the cues that are used for detection. This study included diotic (N₀S₀) and dichotic (N₀S_π) detection of a 500-Hz tone, with either narrowband or wideband masker waveforms. Both diotic and dichotic detection patterns (hit and false alarm rates) across the ensembles of noise maskers were predicted by envelope-slope cues, and diotic results were also predicted by energy cues. The relative importance of energy and envelope cues for diotic detection was explored with a roving-level paradigm that made energy cues unreliable. Most older listeners with normal hearing or mild hearing loss depended on envelope-related temporal cues, even for this low-frequency target. As hearing threshold at 500 Hz increased, the cues for diotic detection transitioned from envelope to energy cues. Diotic detection patterns for young listeners with normal hearing are best predicted by a model that combines temporal- and energy-related cues; in contrast, combining cues did not improve predictions for older listeners with or without hearing loss. Dichotic detection results for all groups of listeners were best predicted by interaural envelope cues, which significantly outperformed the classic cues based on interaural time and level differences or their optimal combination.     

Validation of a French translation of the speech,spatial, and qualities of hearing scale (SSQ) and comparison with other language versions

Objective: To validate a French version of the speech, spatial, and qualities of hearing scale (SSQ), a subjective evaluation of patients’ hearing disability, and to assess SSQ reproducibility across different language versions. Design: The SSQ was translated in accordance with the principles of the ‘Universalist approach’ of cross-cultural adaptation of patient-reported outcome instruments. Scores from a normal-hearing and a hearing-impaired population were compiled and compared, whenever possible, with data from the literature, collected using other language versions. Study sample: One hundred normal-hearing subjects and 230 hearing-impaired subjects. Results: Good reproducibility of scores and inter-subject variability were obtained between several language versions, even if scores found using the French version were slightly lower than those obtained using Dutch or English versions. A comparison of factor analysis outcomes between the English and French versions confirmed good conceptual equivalence across languages and robustness of the SSQ for use in international settings. The three main subscales (speech, spatial, and qualities) confirmed their usefulness in assessing different aspects of hearing disability. Conclusion: This study validated a French-language version of the SSQ, and assessed the reproducibility of the SSQ across subject groups, administration modes, and different countries/languages, confirming its potential as an international standard for hearing disability evaluation.     

Modification of the Threshold Equalising Noise (TEN) test for cochlear dead regions for use with steeply sloping high-frequency hearing loss

Steeply sloping high-frequency hearing loss is often associated with cochlear dead regions. These can be identified by measuring pure-tone thresholds in quiet and in Threshold-Equalising Noise (TEN). However, many patients cannot be adequately tested because the low frequencies in the TEN lead to uncomfortable loudness. We investigated the effect of high-pass filtering on the TEN-test results and the loudness of the TEN. Twenty-four normally hearing subjects and 35 subjects with steeply sloping high-frequency hearing loss were tested, using the standard TEN (TENs), and TEN high-pass filtered at 0.5?kHz (TEN0.5) or 1?kHz (TEN1). For both groups, masked thresholds did not differ across noise types for frequencies above 1?kHz. Over 50% of the hearing-impaired ears tested met the criteria for a dead region at 4?kHz, using all three noise types. However, masked thresholds and the prevalence of positive TEN-test results at 1?kHz were both lower with the TEN1. The TEN1 was judged the most comfortable noise by 68% of the hearing-impaired subjects. We conclude that high-pass filtering would allow testing at higher TEN levels for patients with steeply sloping hearing loss.

Sumario

La hipoacusia de perfil abruptamente descendente en frecuencias agudas se asocia frecuentemente con regiones cocleares muertas. Esto se puede identificar midiendo los umbrales tonales en silencio y en ruido ecualizado al umbral (TEN). Sin embargo, algunos pacientes no pueden ser estudiados adecuadamente porque las frecuencias bajas en el TEN, les produce molestia. Investigamos el efecto del filtro pasa-alto en los resultados de las pruebas TEN y la intensidad subjetiva del TEN. Se examinaron 24 sujetos normoyentes y 35 con hipoacusia de perfil abruptamente descendente en frecuencias agudas, utilizando el TEN habitual y el TEN con filtro pasa/alto a 0.5?kHz (TEN0.5) o 1?kHz (TEN1). Los umbrales de enmascaramiento no difirieron con los diferentes tipos de ruido para las frecuencias por arriba de 1?kHz en ambos grupos. Más del 50% de los oídos hipoacúsicos cumplieron con los criterios para considerar una zona muerta a 4?kHz, con los tres tipos de ruido. Sin embargo, los umbrales de enmascaramiento y la prevalencia de una prueba TEN positiva a 1?kHZ fueron menores con el TEN1. El 68% de los hipoacúsicos consideraron al TEN1 como el ruido más confortable. Concluimos que el filtro pasa-alto puede permitir realizar pruebas con mayor intensidad TEN en pacientes con hipoacusia de perfil abruptamente descendente en frecuencias agudas.     

鼻咽癌患者血清中活性氧、超氧化物歧化酶和谷胱甘肽过氧化物酶活性测定

目的 :测定鼻咽癌患者血清中活性氧 (ROS)、超氧化物歧化酶 (SOD)和谷胱甘肽过氧化物酶 (GSH PX)的活性水平 ,以探讨鼻咽癌患者体内自由基代谢状态及其在鼻咽癌发生、发展中的作用。方法 :分别采用Fenton反应显色法 ,黄嘌呤氧化酶法和二硫代二硝基苯甲酸法对 4 0例鼻咽癌患者 (鼻咽癌组 )和 2 0例健康体检者 (对照组 )血清中ROS、SOD和GSH PX水平进行检测。结果 :鼻咽癌组血清中ROS活性 [(11 32 7.835±4 83.777) /(U·ml-1) ]显著高于对照组 [(10 2 6 2 .712± 5 2 5 .2 87) /(U·ml-1) ](P <0 .0 5 ) ,SOD和GSH PX活性[(76 .6 19± 2 2 .2 83) /(NU·ml-1) ,(98.6 5 3± 4 6 .374 ) /AU ]显著低于对照组 [(15 4 .6 0 3± 2 7.2 4 1) /(NU·ml-1) ,(30 7.872± 116 .2 75 ) /AU](P <0 .0 5 ) ;不同病理类型鼻咽癌患者血清中ROS、SOD和GSH PX活性间的差异均无显著性意义 (P >0 .0 5 )。结论 :鼻咽癌患者体内自由基代谢紊乱 ,抗氧化损伤能力显著下降 ,给予抗氧化治疗有利于抑制鼻咽癌的发展     

Introduction to the Longitudinal Outcomes of Children with Hearing Impairment (LOCHI) study: Background,design, sample characteristics

Abstract

Objective: This article describes the background and the design of the longitudinal outcomes of children with hearing impairment (LOCHI) study, and the characteristics of the study cohort. Design: Children born between 2002 and 2007 who were identified with hearing loss and received audiological intervention by 3 years of age in Australia enrolled in the study. Their demographic characteristics are described. Study sample: Four hundred and fifty-one children in New South Wales, Victoria, and Southern Queensland. Results: Data on age at first hearing-aid fitting for different degrees of hearing loss are reported together with demographic characteristics of the cohort. Conclusion: A unique environment in Australia where all children with varied access to universal newborn hearing screening received the same consistent hearing services from a national hearing service provider makes it possible to investigate the effects of access to early auditory intervention on children's outcomes at a population level.     

Hearing loss and cochlear pathology in the monkey (Macaca) following exposure to high levels of noise

Summary Eight Old World monkeys were exposed 8 h daily for 20 days to octave-band noise having center frequencies from 0.5–8 kHz at levels of 117–120 dB SPL. Two additional animals received exposures to wide-band, 120-dB SPL noise on the same schedule, and one animal was exposed to the 2-kHz octave band for 40 h continuously. Behavioral audiograms were measured throughout exposure and during a 1-month recovery period. Following recovery, the animals were sacrificed and their ears examined histologically. Monaural audiograms are presented showing initial and final TTS and PTS measured at the end of the recovery period. These are compared with complete cytocochleograms for each ear. Hair cell loss was generally restricted to the outer rows, and was reasonably well correlated with pattern of hearing loss. Some cell loss, including inner hair cells, was found in the extreme basal turn, usually without associated high-frequency hearing loss. The relationships between exposure frequency, hearing loss, and locus of cochlear pathology are discussed, as are changes in TTS during exposure.This investigation was supported by research grants NS-05077, NS-05065 and NS-12706 and by Program Project grant NS-05785 from the National Institutes of Health     

Sources of variability of speech,spatial, and qualities of hearing scale (SSQ) scores in normal-hearing and hearing-impaired populations

Objective: To identify and quantify sources of variability in scores on the speech, spatial, and qualities of hearing scale (SSQ) and its short forms among normal-hearing and hearing-impaired subjects using a French-language version of the SSQ. Design: Multi-regression analyses of SSQ scores were performed using age, gender, years of education, hearing loss, and hearing-loss asymmetry as predictors. Similar analyses were performed for each subscale (Speech, Spatial, and Qualities), for several SSQ short forms, and for differences in subscale scores. Study sample: One hundred normal-hearing subjects (NHS) and 230 hearing-impaired subjects (HIS). Results: Hearing loss in the better ear and hearing-loss asymmetry were the two main predictors of scores on the overall SSQ, the three main subscales, and the SSQ short forms. The greatest difference between the NHS and HIS was observed for the Speech subscale, and the NHS showed scores well below the maximum of 10. An age effect was observed mostly on the Speech subscale items, and the number of years of education had a significant influence on several Spatial and Qualities subscale items. Conclusion: Strong similarities between SSQ scores obtained across different populations and languages, and between SSQ and short forms, underline their potential international use.     

A comparative study of the audiological outcomes with Retro-X (semi-implantable hearing aid system) and conventional open fitting hearing aids

The objective of this study was to compare the results of hearing augmentation with the Retro-X semi-implantable hearing aid to a conventional non-implantable open canal hearing aid using the same software technology (Titan-X, auric Hearing Systems, HiKaNo.:13.20.03.0047). Nineteen subjects (20 ears) with mild to moderate high-frequency sensory-neural hearing loss were included in this clinical study. All the subjects were first fitted with a conventional open canal hearing aid (Titan-X). After a period of 4-6 weeks audiological evaluations were performed using standardized speech tests in quiet and noise. Subjective evaluation was performed with the help of standardized questionnaires. After this phase the patients received the semi-implantable Retro-X device under local anaesthesia and 4 weeks later were fitted with a hearing module with the same software technology as the conventional Titan-X hearing aid. Four weeks following the first fitting the same audiological evaluations were performed under similar conditions and the patients were evaluated again using the same questionnaires in order to compare the results of the Retro-X semi-implantable system with the conventional open canal hearing aid. Audiological evaluations revealed better results with the semi-implantable Retro-X in the adaptive speech in noise test; however, the results of the monosyllabic word test in quiet were similar for the Retro-X and conventional open canal hearing aid. The patients subjectively preferred the improved wearing comfort of the semi-implantable device. The Retro-X semi-implantable hearing aid provides better speech perception in noise and higher wearing comfort in comparison to the conventional open canal hearing aids. Considering the simple implantation procedure under local anaesthesia with low complication rate, Retro-X is an alternative to the conventional open canal hearing aids in patients with mild to moderate high frequency sensory-neural hearing loss.     

Effect of treatment with Ginkgo biloba extract EGb 761 (oral) on unilateral idiopathic sudden hearing loss in a prospective randomized double-blind study of 106 outpatients

Objective: Test of dose–response relationship for Ginkgo biloba extract EGb 761 (oral) in outpatients with acute idiopathic sudden sensorineural hearing loss (ISSHL) of at least 15 dB at one frequency within the speech range occurring less than 10 days before study inclusion. Design: Multicentre, randomized, double-blind phase III study comparing dosages of 120 mg twice daily and 12 mg twice daily over 8 weeks. Main endpoint: Recovery (in dB) of the auditory threshold from the initial measurement to the value on the last day of treatment, averaged over those frequencies from 0.25, 0.5, 1, 2, and 3 kHz for which the initial hearing loss amounted to 15 dB or more compared to the level on the opposite side. Patients: 106 patients with an average age of 44 ± 16 years and with hearing loss at affected frequencies 26 dB ± 9 dB included between December 1995 and July 1997. Results: Large majorities of both treatment groups recovered completely. In exploratory analyses of the 96 patients included according to the protocol, patients given the higher dose had less risk of not recovering well (≤10 dB residual hearing loss) (one-sided Fisher test: P = 0.0061), especially if they had no tinnitus (n = 44, P = 0.00702). Conclusion: A higher dosage of EGb 761 (oral) appears to speed up and secure the recovery of ISSHL patients, with a good chance that they will recover completely, even with little treatment. This was already observed after one week of treatment. We find it justified to treat patients who have unilateral ISSHL of less than 75 dB and neither tinnitus nor vertigo with 120 mg oral EGb 761 twice daily. Received: 20 November 2000 / Accepted: 10 April 2001     

Prevalence of auditory neuropathy (AN) among infants and young children with severe to profound hearing loss

Auditory neuropathy is a challenging disorder and needs special habilitative/rehabilitative approach. This study aimed to detect its prevalence among infants and young children with severe to profound hearing loss. 112 infants and young children with age ranged 6-32 months were examined and diagnosed as having severe to profound hearing loss and were referred for hearing aid fitting. Those infants were reassessed in our centers for detecting cases with auditory neuropathy. The study group was subjected to immittancemetry, behavioral observation audiometry, ABR and cochlear microphonics.

Results

15 patients were found to have auditory neuropathy according to our criteria for diagnosis.

Conclusions

The prevalence of AN in the study group was 13.4%. CM were recommended to be tested routinely during ABR assessment whenever abnormal results are obtained.     

遗传性耳聋家系线粒体DNA 961delT/insC(n)突变的致病性分析

目的 探讨线粒体DNA 961delT/insC(n)突变与氨基甙类药物性耳聋的相关性.方法 对一个耳聋家系11个成员采集氨基甙类抗生素用药史、进行听力学检查、表型分析,采集外周静脉血样本,从白细胞中提取DNA,用聚合酶链反应扩增线粒体DNA(mtDNA)全序列,对扩增片段进行DNA测序,对发现的基因突变与耳聋表型进行分离分析.结果 参与研究的所有9例母系成员均检出mtDNA 961delT/insC(n)突变.有明确氨基甙类抗生素用药史的4例中只有2例耳聋患者,其中1例为用药之前出现的先天性聋,另1例为用药后38年出现的轻度耳聋.突变不与耳聋共分离.结论 本研究不支持mtDNA 961de1T/insC(n)突变是该家系耳聋的致病突变,mtDNA 961位点附近可能是一个多变异的区域,mtDNA 961delT/insC(n)可能是一个与氨基甙类药物性耳聋不明确相关的多态.     

The ICF core sets for hearing loss project: International expert survey on functioning and disability of adults with hearing loss using the international classification of functioning,disability, and health (ICF)

Abstract

Objective: To identify relevant aspects of functioning, disability, and contextual factors for adults with hearing loss (HL) from hearing health professional perspective summarized using the ICF classification as reference tool. Design: Internet-based cross-sectional survey using open-ended questions. Responses were analysed using a simplified content analysis approach to link concept to ICF categories according to linking rules. Study sample: Hearing health professionals (experts) recruited through e-mail distribution lists of professional organizations and personal networks of ICF core set for hearing loss steering committee members. Stratified sampling according to profession and world region enhanced the international and professional representation. Results: Sixty-three experts constituted the stratified sample used in the analysis. A total of 1726 meaningful concepts were identified in this study, resulting in 209 distinctive ICF categories, with 106 mentioned by 5% or more of respondents. Most categories in the activities & participation component related to communication, while the most frequent environmental factors related to the physical environment such as hearing aids or noise. Mental functions, such as confidence or emotional functions were also frequently highlighted. Conclusions: More than half (53.3%) of the entire ICF classification categories were included in the expert survey results. This emphasizes the importance of a multidimensional tool, such as the ICF, for assessing persons with hearing loss.     

Cortical auditory evoked potential (CAEP) and behavioural measures of auditory function in a child with a single-sided deafness

Objectives: To study the changes in behavioural and cortical responses over time in a child with single-sided deafness fitted with a cochlear implant (CI).

Methods: Cortical auditory evoked potentials (CAEPs) in noise (+5?dB signal-to-noise ratio) were recorded and auditory skills were assessed using tests of sound localization, spatial speech perception in noise, and self-ratings of auditory abilities (Listening inventory for education, LIFE and Speech, spatial and qualities of hearing questionnaire, SSQ parental version). Measures were obtained prior to and after a CI fitting, including one, six, and 12 months after the CI switch on.

Results: Spatial speech recognition improved over time. At 12 months post-CI, word recognition scores were similar to those of normal hearing children. Signal-to-noise ratios for sentences decreased (i.e. improved) over time post-CI. Sound localization markedly improved at 12 months post-CI compared to baseline. Self-perception of difficulty scores decreased over time. Parental ratings of hearing abilities improved compared to baseline for all subscales. There were changes in the P1–N1–P2 complex at 12 months post-CI, which were clearer frontally across stimuli. Further research is needed to understand the significance of such changes after CI fitting for single-sided deafness.

Conclusion: Although the changes observed could reflect maturational changes, the clinically significant improvement in recognition of speech in noise and improved questionnaire results suggest that the CI was beneficial, consistent with the feedback from the participant.     

10年追踪分析常染色体显性遗传非综合征性耳聋(DFNA41)家系听力学及遗传学特征

目的分析中国一个连续6代常染色体显性遗传性耳聋DFNA41家系的听力学及遗传学特征。方法采用回访调查的方式对家系55位成员进行全身系统检查及临床听力学检测,对部分家系成员采集血样进行候选基因突变筛查。结果该家系所有患者听力损失表现为双侧对称性轻度至重度感音神经性耳聋:40岁以下男性患者听力曲线呈高频下降型;40岁以下女性患者低频受损,听力曲线呈上升型;40岁以上患者,男女均累及全频听力,呈平坦型听力曲线。听力损失程度随着年龄的增长而逐渐加重,至40岁左右时发展为全频中度至重度耳聋。在已完成的11个候选基因突变筛查中,未发现与该家系致病相关的基因突变。结论中国遗传性耳聋DFNA41家系的听力表型与性别及年龄有关,围绕基因型与表型的研究将有助于DFNA41家系致病基因的克隆。