Gender and Oral Contraceptive Effects on Temporary Auditory Effects of Noise

The first experiment examined thresholds at 4 and 8 kHz and the threshold of octave masking at 4 kHz before and after noise for males, females, and females using oral contraceptives. Females using oral contraceptives evidenced greater threshold shifts at 4 kHz than either of the other two groups. The second experiment examined thresholds and the loudness discrimination index at 4 kHz for males and females before and after noise exposure. Females evidenced greater loudness discrimination index changes both with and without noise exposure than did males. In addition, females responded to the noise with cutaneous vasodilation while males evidenced vasoconstriction.     

Electrocochleography during Noise-Induced Temporary Threshold Shifts

The responses of the auditory nerve and brain stem auditory nuclei were recorded non-traumatically in human subjects by means of electrocochleography before, during and after exposure to white noise intensities which produced temporary threshold shifts. The largest decrement (amplitude decrease and latency increase) was seen in the response of the auditory nerve. Large intersubject variability was seen in the effects of the noise exposure on response amplitude, latency and recovery rates     

The Effects of Interruption on Squirrel Monkey Temporary Threshold Shift to a 96-Hour Noise Exposure

6 squirrel monkeys (Saimiri scuireus) were exposed to an octave band of noise with a center frequency of 500 Hz under both continuous and interrupted conditions. Continuous exposures lasted for 4, 8, 16, 24, 48, 72 and 96 h, with complete recovery of hearing before the next exposure. The interrupted exposure was 96 h long with 5-min interruptions so that temporary threshold shift (TTS) could be measured at 2, 4, 8, 12, 16, 24, 36, 48, 60, 72 and 84 h of exposure. There were no differences in TTS from 8 to 96 h of exposure between the two conditions. However, at 4 h of exposure, the interrupted exposure showed significantly less TTS (p < 0.05) than the continuous exposure. The only difference between the exposures was a 5-min interruption at 2 h of exposure during the interrupted exposure. Thus, the interrupted-exposure method is valid for making generalizations about continuous exposures of 8 h or longer. The results also confirmed our previous finding that there was no asymptotic threshold shift for the squirrel monkey although we extended the exposure time to 96 h in this experiment. The similarity of human and squirrel monkey TTS growth functions is consistent with our earlier results and supports the suitability of the squirrel monkey as an animal model for noise-induced hearing loss in humans.     

Effects of the Ovarian and Contraceptive Cycles on Absolute Thresholds,Auditory Fatigue and Recovery from Temporary Threshold Shifts at 4 and 6 kHz

Absolute thresholds at 4 and 6 kHz were tested in three sessions before and after 20 min of exposure to 105 dB(A) pink noise in 12 young normal-cycling females, 11 young females on oral contraceptives and 8 young men. Women on contraceptives showed lower resting thresholds, larger temporary threshold shift (TTS) and higher recovery rates than normal-cycling females. The analysis of resting thresholds, auditory fatigue and recovery from auditory fatigue did not evidence any sex-linked difference. Significant differences linked to the phases of the menstrual cycle and of the contraceptive cycle were observed during recovery from auditory fatigue at 4 kHz and in resting thresholds at 6 kHz. Application of Kendall's coefficient of concordance confirmed these results. Absolute thresholds were highest at menstruation and lowest in the postovulatory phase in normal-cycling females and in women on oral contraceptives, during the days of pill ingestion. Oral contraception is probably a more important factor of change in hearing performance than the phases of the menstrual cycle.     

The Influence of Eye Colour upon Temporary Threshold Shift

Controversy has arisen over the claim that melanin content of the iris as determined by eye colouration bears a direct relationship to susceptibility to temporary threshold shift (TTS). A more comprehensive investigation of TTS has now been carried out which not only confirms the relationship but also indicates that earlier discordant results can be attributed to differences in methodology. The new evidence suggests that for stimulus intensities below 110 dB. (HTL re ISO, 1964) melanin content of the iris exerts its influence predominantly upon auditory adaptation while fatigue effects only become apparent at intensities above this level. The relevance of these findings to hearing conservation measures aimed at the prevention of noise-induced hearing loss is discussed.     

Dependence of the Temporary Threshold Shift on the Immediately Preceding Exposure to Noise

Temporary threshold shift (TTS) measured immediately after exposure to noise here called TTS₁, is surely more difficult to determine in audiological testing, than the usual TTS₂, but in its dependence on the preceding exposure, it is useful in defining criteria for auditory fatigue, for damage and for normal adaptation to noise exposure of short durations. A few results selected from a study using improved methods of measuring TTS₁ confirm the point of view of others in defining regions and limits of normal hearing and auditory fatigue.     

Follow-Up of Auditory-Evoked Potentials and Temporary Threshold Shift in Subjects Developing Noise-Induced Permanent Hearing Loss1

The effects of auditory fatigue, using a temporary threshold shift (TTS) paradigm, on cochlear microphonics (CM) and on auditory brainstem-evoked potentials (ABEP), were studied in normal-hearing subjects during the development of permanent threshold shift (PTS). Behavioral threshold shifts were accompanied by different effects on CM and on ABEP, as PTS was gradually induced by occupational noise. Measures of the effect of increasing stimulus rate (ISR) on ABEP revealed decreased latency shifts during auditory fatigue. ABEP proved useful in early detection of changes in the auditory system, resulting from exposure to noise. In addition, this study further supports the suggestion that TTS acts as a peripheral attenuator of the effect of ISR on the central auditory pathway.

On a étudié les effets de la fatigue auditive sur le microphonique cochléaire (MC) et les réponses du tronc cérébral (RTC) en utilisant le déplacement temporaire du seuil (DTS), sur des sujets normo-entendants, pendant le développement du seuil de déplacement permanent. Les changements dans les seuils subjectifs sont accompagnés d'effets différents sur le MC et les RTC. L'accroissement du rythme de stimulation (ARS) réduit les changements de latence durant la fatigue auditive. Les RTC permettent de détecter précocement les changements auditifs dus au bruit. Cette étude suggère en outre que le DTS interviendrait comme un atténuateur périphérique des effets de l'ARS sur les voies auditives centrales.     

Different effects of noise and salicylate and their interactions on the guinea pig cochlea

We investigated the effects of noise and salicylate on the guinea pig cochlea by monitoring the acoustic nerve compound action potential (CAP) as well as the 2f1-f2 distortion product in the cochlear microphonics (DP-CM). The alterations of DP-CMs by noise and salicylate revealed an apparent difference, even when the noise-induced and salicylate-induced CAP threshold shifts were equal. This result indicated that noise and salicylate might have an effect on different sites in the cochlea. Combined effects were altered by changing the order in which the two agents were applied. The existing noise-induced damage attenuated the additional ototoxicity of salicylate. In contrast, attenuation did not occur when salicylate administration preceded noise exposure. Considering known effects of noise and/or salicylate altering mechano-electrical transduction (MET) and electro-mechanical transduction of the cochlear outer hair cells, our results seem to suggest that the MET plays a key role in the transduction mechanism in the cochlea.     

The influence of moderate-intensity noise on the click-evoked compound action potential of the guinea pig,Cavia porcellus

Summary Noise-induced alterations of the click-evoked compound potential (CAP) were studied by means of electrodes chronically implanted near the round window in 15 pigmented guinea pigs aged 3–6 months. The potentials were recorded before, during and after exposure to continuous pink noise maintained at an intensity of 80, 90 or 100 dB SPL for 120 h. During the exposure phase the CAP thresholds of all the animals tested increased exponentially, nearly leveling out by approximately 48 h to form an asymptotic threshold shift. Recovery after the end of exposure also occurred exponentially, with a return to the original threshold for neural excitation after at most 72 h. There was no detectable change in amplitude, latency or inter-peak interval of the CAP when correlated with the change in threshold.With the support of the Deutsche Forschungsgemeinschaft     

Auditory Evoked Potentials and Audiological Foliow-Up of Subjects Developing Noise-Induced Permanent Threshold Shift

Three examinations, including cochlear microphonics (CM) to 99/s 1 -kHz tones and auditory brainstem evoked potentials (ABEP) to 10/s and 55/s clicks, as well as psychoacoustical tests, were performed on 31 normally hearing subjects, exposed to occupational noise for over a year. The results showed prolongation of the absolute latency of peaks I, III and V, without significant changes in interpeak latency differences (IPLD) or CM latency. The site affected by increasing stimulus rate, giving rise to increased IPLD, appears to be central rather than cochlear. The efficacy of increased stimulus rate in detecting noise-induced auditory changes was higher than that achieved applying the 10/s click rate.

Nous avons precédé à trois examens consecutifs sur 31 sujets audiométriquement normaux mais exposés au bruit depuis plus d'un an. Chaque examen comprend l'enregistrement du potentiel microphonique cochléaire (CM) et des reponses du tronc cerebral (ABEP) évoquées par des clics aux cadences de stimulation de 10/s et de 55/s. De měme, des tests psychoacoustiques ont été faits. Les résultats ont montré une prolongation des latences absolues des pics I, III et Vsans changement significatif dans les différences de latences inter-pics (IPLD) ou dans le CM. L'influence d'une augmentation de la cadence de stimulation paraiˇt d'origine centrale plutôt que cochléaire. On a observé que la cadence rapide était plus efficace pour détecter les changements auditifs causés par le bruit.     

短时纯音暴露对正常人畸变产物耳声发射幅值及频谱时间序列的影响

探讨在耳蜗功能早期轻微损害时畸变产物耳声发射（ＤＰＯＡＥ）幅值及频谱时间序列的特征,促进ＤＰＯＡＥ的临床应用。方法：用 １３０ｄＢ ＳＰＬ的 ４ ｋＨｚ纯音对 １５例听力正常人（３０耳）进行 ３ ｍｉｎ的短时暴露,造成听力暂时性阈移后,用ＩＬＯ－９０耳声发射仪记录、分析暂时性阈移（ＴＴＳ）时ＤＰＯＡＥ的幅值、时间序列的特征,并与纯音暴露前进行对比。结果：正常人经过短时纯音暴露后,０．５,１,２ ｋＨｚ纯音和宽带噪声的声反射阈升高,纯音暴露前后０．５、１、２ ｋＨｚ与ＢＢＮ之间的平均反射阈差值分别为（９．７８±６．９８）,（８．０４±５．５８）,（１３．０±５．５８） ｄＢ ＨＬ和（８．８２±６．２３）,（５．７５±４．４２）,（９．０５±２．２７）ｄＢ ＨＬ,声反射阈差值缩小。纯音暴露前后６ ｋＨｚＤＰＯＡＥ幅值分别为（６．００±３．４５）和（１．７２±１. ２３） ｄＢ ＳＰＬ,降低４．２８ ｄＢ ＳＰＬ,时间序列变异系数为（５．１８±１．６３）％,时间序列曲线稳定性降低,ＤＰＯＡＥ幅值与时间序列结合发现８０％的人ＤＰＯＡＥ处于异常范围。结论：ＤＰＯＡＥ的幅值与时间序列结合分析有诊断耳蜗功能早期轻微受损的临床价值。     

Effects of Contralateral Acoustic Stimulation on Spontaneous Otoacoustic Emissions and Hearing Threshold Fine Structure

Medial olivocochlear (MOC) influence on cochlear mechanics can be noninvasively, albeit indirectly, explored via the effects of contralateral acoustic stimulation (CAS) on otoacoustic emissions. CAS-mediated effects are particularly pronounced for spontaneous otoacoustic emissions (SOAEs), which are typically reduced in amplitude and shifted upward in frequency by CAS. We investigated whether similar frequency shifts and magnitude reductions were observed behaviorally in the fine structure of pure-tone hearing thresholds, a phenomenon thought to share a common underlying mechanism with SOAEs. In normal-hearing listeners, fine-resolution thresholds were obtained over a narrow frequency range centered on the frequency of an SOAE, both in the absence and presence of 60-dB SPL broadband CAS. While CAS shifted threshold fine structure patterns and SOAEs upward in frequency by a comparable amount, little reduction in the presence or depth of fine structure was observed at frequencies near those of SOAEs. In fact, CAS typically improved thresholds, particularly at threshold minima, and increased fine structure depth when reductions in the amplitude of the associated SOAE were less than 10 dB. Additional measurements made at frequencies distant from SOAEs, or near SOAEs that were more dramatically reduced in amplitude by the CAS, revealed that CAS tended to elevate thresholds and reduce threshold fine structure depth. The results suggest that threshold fine structure is sensitive to MOC-mediated changes in cochlear gain, but that SOAEs complicate the interpretation of threshold measurements at nearby frequencies, perhaps due to masking or other interference effects. Both threshold fine structure and SOAEs may be significant sources of intersubject and intrasubject variability in psychoacoustic investigations of MOC function.     

葛根素对急性低气压环境下噪声性听器损伤的防治作用

目的探讨葛根素对模拟急性低气压环境下噪声性听器损伤的防治作用.方法将60只听力正常豚鼠随机分为正常组、阳性对照组、葛根素防治组和葛根素治疗组.后3组置于模拟高原海拔5 500 m低气压环境,130 dB SPL白噪声持续刺激8小时;防治组和治疗组每日腹腔注射葛根素注射液(150 mg/kg).观察各组的听性脑干反应(ABR)反应阈、耳蜗形态学改变、血液流变学和血清丙二醛(MDA)、超氧化物岐化酶(SOD)含量的变化.结果出舱后8小时,各组ABR阈移最大,对照组、防治组在1 kHz的阈移分别为33.67±5.40、26.50±4.76 dB,在8 kHz的阈移分别为59.33±5.20、48.67±4.70 dB(P＜0.01);高频听力损失较低频严重(P＜0.01).以后各组ABR阈移逐渐恢复,给药两组恢复程度均较对照组明显(P＜0.01).形态学改变与听力变化一致.防治组血清MDA含量显著低于对照组,用药的两组血清SOD均高于对照组.对照组血液流变学全血粘度值明显升高,与用药两组比较有显著性差异.结论葛根素对急性低气压环境下的听器损伤具有一定的防治效果,可能与其改善微循环和血液流变学特性、抗氧化自由基的作用有关.     

喉内肌、声门下压力、气流率在调节基频中的作用

当16名正常受试者从最低音、中音、高音及假声发元音“i”时，对其环甲肌、甲杓肌做了肌电图检查。同时对20名音乐学院声乐系学生个音域的频率、声强、声门下压力、气流率进行了测量。结果表明：随着发音频率的升高，环甲肌及甲杓肌的电激动逐渐增强。在最低音发音时环甲肌的电活动较小，没有甲杓肌强。在高音及假声发音时，环甲肌电活动最强，尤其在假声音域，环甲肌与甲杓肌共同协作作用来完成对频率的调节。当发音频率逐渐升高时，声强及声门下压力同样也逐渐升高，呈正相关（P＜0．01）。频率与气流率也为正相关（P＜0．01，除2个男低音之外），有10名受试者在发高音和假声时，气流率的值呈现零值和负值。声门下压力及喉内肌的电活动在调节基频中起到了重要的作用，气流率在调节基频中也有一定的作用，但在发高音和假声时，有1／2的受试者的气流率几乎没有起作用，呈现零值或负值。     

The Effect of Gaussian Noise on the Threshold,Dynamic Range,and Loudness of Analogue Cochlear Implant Stimuli

The deliberate addition of Gaussian noise to cochlear implant signals has previously been proposed to enhance the time coding of signals by the cochlear nerve. Potentially, the addition of an inaudible level of noise could also have secondary benefits: it could lower the threshold to the information-bearing signal, and by desynchronization of nerve discharges, it could increase the level at which the information-bearing signal becomes uncomfortable. Both these effects would lead to an increased dynamic range, which might be expected to enhance speech comprehension and make the choice of cochlear implant compression parameters less critical (as with a wider dynamic range, small changes in the parameters would have less effect on loudness). The hypothesized secondary effects were investigated with eight users of the Clarion cochlear implant; the stimulation was analogue and monopolar. For presentations in noise, noise at 95% of the threshold level was applied simultaneously and independently to all the electrodes. The noise was found in two-alternative forced-choice (2AFC) experiments to decrease the threshold to sinusoidal stimuli (100 Hz, 1 kHz, 5 kHz) by about 2.0 dB and increase the dynamic range by 0.7 dB. Furthermore, in 2AFC loudness balance experiments, noise was found to decrease the loudness of moderate to intense stimuli. This suggests that loudness is partially coded by the degree of phase-locking of cochlear nerve fibers. The overall gain in dynamic range was modest, and more complex noise strategies, for example, using inhibition between the noise sources, may be required to get a clinically useful benefit.     

Effects of Stimulation Rate, Mode and Level on Modulation Detection by Cochlear Implant Users

In cochlear implant (CI) patients, temporal processing is often poorest at low listening levels, making perception difficult for low-amplitude temporal cues that are important for consonant recognition and/or speech perception in noise. It remains unclear how speech processor parameters such as stimulation rate and stimulation mode may affect temporal processing, especially at low listening levels. The present study investigated the effects of these parameters on modulation detection by six CI users. Modulation detection thresholds (MDTs) were measured as functions of stimulation rate, mode, and level. Results show that for all stimulation rate and mode conditions, modulation sensitivity was poorest at quiet listening levels, consistent with results from previous studies. MDTs were better with the lower stimulation rate, especially for quiet-to-medium listening levels. Stimulation mode had no significant effect on MDTs. These results suggest that, although high stimulation rates may better encode temporal information and widen the electrode dynamic range, CI patients may not be able to access these enhanced temporal cues, especially at the lower portions of the dynamic range. Lower stimulation rates may provide better recognition of weak acoustic envelope information.     

地铁车厢内噪声对不同类型耳机佩带舒适音量的影响

目的 探讨地铁车厢内噪声对不同类型耳机佩戴者使用音量的影响.方法 以75例听力正常受试者为研究对象,每例对象分别佩戴入耳式、耳塞式、贴耳式和耳罩式耳机,在安静环境和北京地铁7号线车厢背景噪声(LAeq,1s均值为80.3 dB A)下听同一首音乐,选择舒适的音量档位,分析背景噪声、耳机类型对受试者耳机使用音量的影响.结果 在地铁车厢噪声环境下,受试者使用入耳式、耳塞式、贴耳式和耳罩式耳机选择舒适音量时人耳处噪声值分别为76.6±4.7、84.3±5.0、82.3±4.2、80.8±4.2 dB A,安静环境下分别为65.5±6.8、71.9±7.1、69.5±7.5、67.9±7.3 dB A;从安静环境到地铁车厢噪声环境,受试者的舒适音量平均提高了10 dB A以上.根据WHO噪声性聋的限值计算得到,不佩戴耳机每天暴露在上述地铁车厢背景噪声下不超过134 mins,使用上述耳机时时长分别不超过315、54、85、120 mins,可以避免噪声性听力损伤的发生.结论 地铁车厢噪声和耳机类型对耳机使用者舒适音量的影响较大;在地铁车厢嘈杂环境中,使用隔声性能较好的入耳式耳机,尽管调高了耳机舒适音量,人耳处实际噪声暴露水平仍可能低于不使用耳机时车厢噪声水平.     

模拟失重和噪声对大鼠听功能及耳蜗Corti 器损伤的协同作用

目的：探讨模拟失重和噪声对大鼠听功能及耳蜗Corti器损伤的协同作用。方法48只大鼠随机分为空白组、失重组、噪声组和失重＋噪声组,每组12只。失重组以Morey －Holton法模拟失重环境,噪声组暴露的噪声环境为模拟航天载人飞船内复合噪声,包括72±2 dB SPL的持续稳态噪声和160 dB SPL的脉冲噪声,失重＋噪声组则同时暴露于上述失重及噪声环境中,空白组常规饲养,不做任何处理。分别于暴露1周和2周后,每组随机选出6只大鼠行ABR阈值检测后取材行 HE染色、免疫荧光（DAPI）染色及扫描电镜观察耳蜗的形态学变化。结果暴露2周后大鼠ABR阈值较暴露1周时升高,失重＋噪声组ABR阈值最高（ P＜0．01）,其次为噪声组。HE染色示暴露1周和2周后除空白组外各组大鼠耳蜗Corti器均有不同程度的损伤,失重＋噪声组最严重。免疫荧光染色示暴露1周后大鼠耳蜗毛细胞死亡方式以肿胀坏死为主,失重＋噪声组最严重（肿胀率10％）,其次为噪声组（肿胀率3．33％）;暴露2周后大鼠耳蜗外毛细胞以核缺失为主,失重＋噪声组缺失率最高（缺失率13．6％）,其次为噪声组（缺失率12．7％）,失重组毛细胞缺失以内毛细胞为主。扫描电镜示,失重＋噪声组毛细胞静纤毛损伤最严重,其次为噪声组,再次为失重组。结论模拟失重和噪声环境对大鼠听功能的影响有协同作用,且这种协同作用对耳蜗Corti器有显著的损伤作用。     

模拟中长期微重力和噪声环境对大鼠听功能及内耳毛细胞凋亡的影响

目的 研究模拟中长期微重力和噪声环境对大鼠听功能及内耳细胞凋亡的影响.方法 36只SD大鼠随机分为两组:空白组(6只)和实验组(30只).实验组给予持续尾部悬吊模拟微重力及飞船舱内噪声(稳态噪声+脉冲噪声)暴露,分别于悬吊及暴露前、悬吊及暴露3天、1周、2周、4周和8周后检测双耳ABR反应阈,并于悬吊及暴露3天、1周、2周、4周和8周取实验动物耳蜗行免疫组化染色观察半胱氨酸天冬氨酸蛋白酶3(caspase-3)在内耳的表达.空白组不做任何处理,常规饲养,于实验前及实验3天、1周、2周、4周和8周分别检测双耳ABR反应阈,并于饲养8周后取耳蜗行免疫组化染色观察.结果 实验前两组大鼠ABR反应阈差异无统计学意义(P＞0.05).实验组大鼠悬吊及噪声暴露后各时间点ABR反应阈较空白组均明显增高(P＜0.01),悬吊及暴露4周实验组大鼠ABR反应阈为90.00±4.26 dB SPL,明显高于3天、1周、2周及8周时(P＜0.05);悬吊及暴露8周大鼠ABR反应阈(80.00±5.22 dB SPL)有所下降,与暴露2周(85.00±4.77 dB SPL)、4周大鼠比较差异有统计学意义(P＜0.01).悬吊及噪声暴露后大鼠内耳细胞caspase-3的表达较空白组明显增强,且在一定时间内随暴露时间的延长其表达有逐渐增强的趋势,尤以悬吊及暴露4周时最明显,暴露8周时其表达强度较4周时明显下降.结论 模拟中长期微重力和噪声环境对大鼠的听功能有明显损伤,且与内耳细胞凋亡呈相同的趋势;微重力和噪声因素造成的听功能损伤可能与内耳细胞的凋亡有关.     

Effects of age, body mass index, and gender on nasal airflow rate and pressures.

OBJECTIVES: The purpose of this study was to evaluate the variation of airflow rate and oral-nasal pressure with age, body mass index (BMI), and gender (i.e., to evaluate whether the effects of age, BMI, and gender on airflow rate and pressures are convergent with their effects on nasal cross-sectional area and resistance). STUDY DESIGN: A cross-sectional study of 332 subjects (214 female and 118 male subjects) aged 16 to 82 years. METHODS: The aerodynamic measurements of nasal airflow rate and nasal and oral pressures were performed by posterior rhinomanometry. Age, gender, weight, and height were recorded for each subject, and the BMI was calculated. The effects of age, BMI, and gender on airflow rate and nasal and oral pressures were estimated by ANOVA. RESULTS: Nasal airflow rate and oral and nasal pressures increased with increasing BMI. In addition, the mean values of airflow rate and pressures were significantly higher in male than in female subjects. Increasing age was related to increased oral pressure, but was not associated with airflow rate or nasal pressure. CONCLUSIONS: This study suggests that, on the contrary to the findings in children and adolescents, BMI and gender should be taken into consideration when measuring the patency of upper airway in adults.