骨导声诱发的耳声发射耳蜗图

用不同频率的短纯音骨导刺激,在7名(14耳)听力正常受试者同时记录双耳声诱发耳声发射(EOAE)。此法比单耳轮流记录省时一半。研究结果表明,EOAE 为一种窄带声,其中心频率随刺激声频率增高而增高,提示 EOAE 产生部位在接受刺激声频率对应的耳蜗部位附近。EOAE 的潜伏期与刺激强度无明显关系,但有随刺激声频率增高而变短的趋势,可能与不同频率刺激声诱发的 EOAE 在基底膜上产生的部位与鼓膜之间的距离不等有关。除1耳用4.0kHz 外,用1.0,2.0,3.0和4.0kHz 短纯音刺激在14耳全可记录到 EOAE,0.5kHz和6.0kHz 则分别在10耳和7耳记录到 EOAE。0.5—6.0kHz 短纯音诱发的 EOAE 的阈值均值连线所得的声发射耳蜗图上可见,1.0kHz 处阈值最低,而在这些受试者所测得的中耳共振频率平均值为1100±230Hz,推测1.0kHz EOAE 阈值最低与中耳的传导函数有关。本文描述的骨导双耳同时记录 EOAE 并描记声发射耳蜗图的方法可用于临床的听力客观评价。     

广义时频分析方法在耳声发射研究中的应用Ⅱ.短声与短纯音诱发耳声发射信号的时频分布

为了进一步探讨耳声发射的产生机制,需要研究不同类型刺激诱发的耳声发射之间的相互关系.主要研究短声与短纯音诱发的耳声发射,用广义时频分析方法中的锥形核分布分别计算了它们的时频分布,从其时频分布分析了它们之间的相互关系.结果表明:具有不同中心频率的短纯音刺激诱发耳声发射的时频分布的迭加与短声刺激诱发的耳声发射的时频分布具有相似性,两者时频分布中的主要频率成分数目、潜伏期和持续时间完全相同,它们高度的相关性支持了短声与短纯音诱发的耳声发射具有共同的产生器的观点.     

长江鲟幼鱼的听觉阈值研究

试验采用室内噪声控制的方式模拟野外自然噪声环境, 以长江鲟(Acipenser dabryanus Dumeril)幼鱼为实验对象, 使用TDT听觉测试系统, 在100—500 Hz的刺激频率下, 通过听性脑干反应(Auditory Evoked Potential, AEP法)测定其听力阈值。结果显示, 长江鲟的最敏感频率为300 Hz, 声压为(133±0.5) dB, 听力曲线呈“V”型, 听觉阈值随着频率的不同而发生变化。总体看, 长江鲟听觉阈值较高, 听力较弱, 不能听到500 Hz以上的声音, 其中, 长江鲟的听觉阈值与湖鲟和匙吻鲟等鲟鱼类基本相似, 但比长江中常见的淡水鱼类的听觉阈值高、听频范围窄。研究结果将为长江鲟的野外放归和种群重建提供重要基础资料, 为评价涉渔工程建设运行对长江鱼类的影响提供基础数据支撑。     

稳态视觉诱发电位神经网络间的相互作用

稳态视觉诱发电位(steady-state visual evoked potential,SSVEP)不同于瞬态视觉诱发电位,有其独特的产生机理。当用两种不同频率的闪光同时刺激时,每种频率闪光诱发的SSVEP之间是否会相互影响?它们与对应单一频率闪光刺激时产生的SSVEP的关系怎样?作者用!波段频率8.3Hz与"波段频率20Hz的闪光分别及同时刺激10个被试的双眼,发现在同时刺激时,每种频率闪光的SSVEP比对应单频刺激时的SSVEP略小,但位置分布无明显变化。这说明不同频率SSVEP的产生网络是彼此独立的,在被同时激活时,每个网络产生的信号并不相互影响。     

广义时频分析方法在耳声发射研究中的应用 Ⅱ.短声与短纯音诱发耳声发射信号的时频分布

为了进一步探讨耳声发射的产生机制,需要研究不同类型刺激诱发的耳声发射之间的相互关系,主要研究短声与短纯音诱发的耳声发射,用广义时频分析方法中的锥形核分布分别计算了它们的时频分布,从其时频分布分析了它们之间的相互关系。结果表明：具有不同中心频率的短纯音刺激诱发耳声发射的时频分布的迭加与短声刺激诱发的耳声发射的时频分布具有相似性,两者时频分布中的主要频率成分数目、潜伏期和持续时间完全相同,它们高度的相     

重复短声调频在豚鼠诱发的皮层慢反应及反应阈

重复短声调频在豚鼠诱发的皮层慢反应的基本特征与其他声刺激诱发者相似,它为一正负正三相波,第一正峰的潜伏期约50ms。以调频深度表示的反应阈△f_r较易测定,可以作为动物频率辨别能力的定量表达。对从250至4000pps的复频,豚鼠△fr的均值只在2.0至2.6pps间波动,因此对需要比较不同状况时△fr的变化,一般只取复频1000pps的△f_r便可代表,不必取整个△f_r曲线。听觉系统对重复短声的频率变化比纯音的容易检别,本文对可能的机理进行了讨论。     

蟾蜍延脑听中枢的单位电反应的一些观察

我们利用电生理学的方法测定了蟾蜍延脑听反应的区域,并研究了延脑听神经元对短声及纯音的反应特性。结果表明:1.从内耳来的传入冲动主要是向同侧的延脑听区传递的。2.蟾蜍听觉系统感受的频率范围在4,000周/秒以下,对于500—600周/秒以及1,000—1,200周/秒的频率最为敏感。多数听神经元的反应阈值在人听阈上25—35分贝左右。少数在人听阈上5—10分贝或45—55分贝。3.根据短声及特征频率的纯音所引起的反应,可将延脑听神经元的反应分为长潜伏期(平均约12毫秒)及短潜伏期(平均约3毫秒)两种形式。反应潜伏期的长短,可能是由不同类型的神经元的特性所决定的,但在同一神经元,在改变声音刺激的频率或强度时,反应的潜伏期也有变化。4.延脑听神经元对纯音刺激的反应有连续发放的、给声的、给-撤声的以及撤声的几种形式。其中以连续发放的反应形式最为常见。5.有时,纯音引起的连续发放是迭加在振幅达十几毫伏的正相慢波之上的,发放的波形为正单相锋形电位,它的上升相较陡,下降相缓慢。短声也可以引起这样的锋形电位,它们可能是细胞内记录到的反应。     

诱发性耳声发射向40-Hz听觉相关电位及行为反应间的相关分析

以500-Hz短纯音作为刺激声,分别测定了20位受试者(9例正常者,11例耳病患者,共40耳)的诱发性耳声发射(EOAE),40-Hz听觉相关电位(40-Hz AERP)和行为反应三项指标的阈值。结果如下:EOAE阈值的主要分布范围在〔20,60〕dB nHL,该范围耳数是其阈值总范围〔15,70)dB nHL耳数的93％;40-Hz AERP阈值主要在〔20,60〕dB nHL,耳数是其阈值范围〔20,90〕dB nHL耳数的95％;行为阈主要在〔20,40〕dB nHL,耳数是其阈值范围〔15,80〕dB nHL耳数的91％,全部受试者有13耳EOAE未引出(正常者3耳,耳病患者10耳),占总测试耳数的33％。三项指标的相关分析表明:EOAE—40Hz AERP,EOAE—行为反应,40Hz AERP一行为反应的r值分别为0.609(0.002相似文献   

强噪声引起的ABRⅤ波振幅增大现象

为研究噪声作用后听觉中枢诱发反应振幅变化,用豚鼠记录了器材怕作用前后皮层诱发反应（ACER）和脑干诱发反应（ABR）的振幅和潜伏期,比较了暴露噪声前后短声刺激系列强度中ACER和ABR最大振幅和潜伏期,110dBA宽带噪声作用30分钟后,听阈提高53dB,ACER最大振幅增大24%,1小时后仍为24%,2小时后增大28%,峰间潜伏期（P1-P2）比暴露前缩短,噪声作用后ABRV波最大振幅增大15%,1小时后为21%,2小时后为28%,潜伏期比暴露前缩短,AP、ABP、Ⅰ、Ⅲ。Ⅳ波最大振幅均经暴露前减小。结果表明,强噪声作用后ACER存在振幅增大,同时ABRV波也有振幅增大现象。     

诱发性耳声发射向40-Hz听觉相关电位及行为反应间的相关分析

以500-Hz短纯音作为刺激声,分别测定了20位受试者(9例正常者,11例耳病患者,共40耳)的诱发性耳声发射(EOAE),40-Hz听觉相关电位(40-Hz AERP)和行为反应三项指标的阈值。结果如下:EOAE阈值的主要分布范围在〔20,60〕dB nHL,该范围耳数是其阈值总范围〔15,70)dB nHL耳数的93％;40-Hz AERP阈值主要在〔20,60〕dB nHL,耳数是其阈值范围〔20,90〕dB nHL耳数的95％;行为阈主要在〔20,40〕dB nHL,耳数是其阈值范围〔15,80〕dB nHL耳数的91％,全部受试者有13耳EOAE未引出(正常者3耳,耳病患者10耳),占总测试耳数的33％。三项指标的相关分析表明:EOAE—40Hz AERP,EOAE—行为反应,40Hz AERP一行为反应的r值分别为0.609(0.002相似文献   

Aerial hearing thresholds and detection of hearing loss in male California sea lions (Zalophus californianus) using auditory evoked potentials

Auditory evoked potential (AEP) measurements are useful for describing the variability of hearing among individuals in marine mammal populations, an important consideration in terms of basic biology and the design of noise mitigation criteria. In this study, hearing thresholds were measured for 16 male California sea lions at frequencies ranging from 0.5 to 32 kHz using the auditory steady state‐response (ASSR), a frequency‐specific AEP. Audiograms for most sea lions were grossly similar to previously reported psychophysical data in that hearing sensitivity increased with increasing frequency up to a steep reduction in sensitivity between 16 and 32 kHz. Average thresholds were not different from AEP thresholds previously reported for male and female California sea lions. Two sea lions from the current study exhibited abnormal audiograms: a 26‐yr‐old sea lion had impaired hearing with a high‐frequency hearing limit (HFHL) between 8 and 16 kHz, and an 8‐yr‐old sea lion displayed elevated thresholds across most tested frequencies. The auditory brainstem responses (ABRs) for these two individuals and an additional 26‐yr‐old sea lion were aberrant compared to those of other sea lions. Hearing loss may have fitness implications for sea lions that rely on sound during foraging and reproductive activities.     

Stimulus variability affects the amplitude of the auditory steady-state response

In this study we investigate whether stimulus variability affects the auditory steady-state response (ASSR). We present cosinusoidal AM pulses as stimuli where we are able to manipulate waveform shape independently of the fixed repetition rate of 4 Hz. We either present sounds in which the waveform shape, the pulse-width, is fixed throughout the presentation or where it varies pseudo-randomly. Importantly, the average spectra of all the fixed-width AM stimuli are equal to the spectra of the mixed-width AM. Our null hypothesis is that the average ASSR to the fixed-width AM will not be significantly different from the ASSR to the mixed-width AM. In a region of interest beamformer analysis of MEG data, we compare the 4 Hz component of the ASSR to the mixed-width AM with the 4 Hz component of the ASSR to the pooled fixed-width AM. We find that at the group level, there is a significantly greater response to the variable mixed-width AM at the medial boundary of the Middle and Superior Temporal Gyri. Hence, we find that adding variability into AM stimuli increases the amplitude of the ASSR. This observation is important, as it provides evidence that analysis of the modulation waveform shape is an integral part of AM processing. Therefore, standard steady-state studies in audition, using sinusoidal AM, may not be sensitive to a key feature of acoustic processing.     

Effects of oral contraceptives and of the ovarian cycle on auditory performance at 4 and 6 kHz. Demonstration by functional audiometry

Absolute thresholds at 4 and 6 kHz were tested in 3 sessions before and after 20 min exposure to 105 dB (A) pink noise in 12 young normal cycling females 11 young females under oral contraceptives and 8 young men. Women under oral contraceptives show lower resting thresholds, more important TTS2 and higher recovery rate than normal cycling women and men. In normal cycling females, non parametric analysis of the data provides evidence that absolute thresholds at 4 and 6 kHz tend significantly to be higher at menses and lower during the postovulatory phase of the cycle.     

TEMPORARY THRESHOLD SHIFTS AFTER NOISE EXPOSURE IN THE BOTTLENOSE DOLPHIN (TURSIOPS TRUNCATUS) MEASURED USING EVOKED AUDITORY POTENTIALS

The time course of recovery from temporary threshold shift (TTS) was measured in a bottlenose dolphin, Tursiops truncatus , using an evoked-potential procedure. The envelope-following response (EFR), which is a rhythmic train of auditory brainstem responses (ABR) to sinusoidally amplitude-modulated tones, was used as an indicator of the sound reception by the animal. Variation of the intensity of the stimulus allowed us to measure the animal's hearing via EFR thresholds. During each session, following an initial measure of threshold, the trained animal voluntary positioned itself within a hoop 1 m underwater while a 160 dB re 1 μPa noise of a 4–11 kHz bandwidth was presented for 30 min. After the noise exposure, thresholds were measured again at delays of 5, 10, 15, 25, 45, and 105 min. Measurements were made at test frequencies of 8, 11.2, 16, 22.5, and 32 kHz. The maximum TTS occurred 5 min after exposure and rapidly recovered with a rate of around 1.5 dB per doubling of time. TTS occurred at test frequencies from 8 to 16 kHz, with the maximum at 16 kHz. TTS was negligible at 22.5 kHz and absent at 32 kHz.     

A complex relationship among chemical concentration, detection threshold, and suprathreshold intensity of bitter compounds

Detection thresholds and psychophysical curves were established for caffeine, quinine-HCl (QHCl), and propylthiouracil (PROP) in a sample of 33 subjects (28 female mean age 24 +/- 4). The mean detection threshold (+/-standard error) for caffeine, QHCl, and PROP was 1.2 +/- 0.12, 0.0083 +/- 0.001, and 0.088 +/- 0.07 mM, respectively. Pearson product-moment analysis revealed no significant correlations between detection thresholds of the compounds. Psychophysical curves were constructed for each bitter compound over 6 concentrations. There were significant correlations between incremental points of the individual psychophysical curves for QHCl and PROP. Regarding caffeine, there was a specific concentration (6 mM) below and above which the incremental steps in bitterness were correlated. Between compounds, analysis of psychophysical curves revealed no correlations with PROP, but there were significant correlations between the bitterness of caffeine and QHCl at higher concentrations on the psychophysical curve (P<0.05). Correlation analysis of detection threshold and suprathreshold intensity within a compound revealed a significant correlation between PROP threshold and suprathreshold intensity (r=0.46-0.4, P<0.05), a significant negative correlation for QHCl (r=-0.33 to -0.4, P<0.05), and no correlation for caffeine. The results suggest a complex relationship between chemical concentration, detection threshold, and suprathreshold intensity.     

Auditory evoked potentials in the Japanese monkey.

Auditory sensitivity based on auditory brain stem response (ABR), whole nerve action potential (AP), and cochlear microphonics (CM) to tone bursts of 0.5-8 kHz were compared with behavioral audiometry in the Japanese monkeys. Although sensitivity loss at 4-6 kHz was observed in these potentials, an increase in sensitivity at 8 kHz was obtained only in the ABR. Thus the sensitivity loss at 4-6 kHz originates at the peripheral system and the increased sensitivity at 8 kHz originates at the central.     

Manganese in toenails is associated with hearing loss at high frequencies in humans

Purpose: Elevated hearing thresholds from high frequencies are known to be one of the hallmarks of age-related hearing loss. Our recent study showed accumulation of manganese (Mn) in inner ears resulting in acceleration of age-related hearing loss in mice orally exposed to Mn. However, there is no evidence showing an association between Mn in non-invasive biological samples and hearing loss in humans evaluated by pure tone audiometry (PTA). In this study, we evaluated Mn in non-invasive biological samples as a possible biomarker for hearing loss in humans.

Materials and methods: We determined hearing levels by PTA and Mn levels in toenails, hair and urine with an inductively coupled plasma mass spectrometer (ICP-MS) in 145 healthy subjects in Bangladesh.

Results: Multivariable analyses showed that Mn levels in toenails, but not in hair and urine samples, were significantly associated with hearing loss at 8?kHz and 12?kHz. Moreover, our experimental study showed a significant correlation between Mn levels in inner ears and nails, but not hair, in mice orally exposed to Mn.

Conclusions: The results provide novel evidence that Mn in toenails is a possible biomarker for hearing loss at high frequencies in humans.     

Effects of Boat Engine Noise on the Auditory Sensitivity of the Fathead Minnow, Pimephales promelas

Fishes are constantly exposed to various sources of noise in their underwater acoustic environment. Many of these sounds are from anthropogenic sources, especially engines of boats. Noise generated from a small boat with a 55 horsepower outboard motor was played back to fathead minnows, Pimephales promelas, for 2 h at 142 dB (re: 1 Pa), and auditory thresholds were measured using the auditory brainstem response (ABR) technique. The results demonstrate that boat engine noise significantly elevate a fish's auditory threshold at 1 kHz (7.8 dB), 1.5 kHz (13.5 dB), and 2.0 kHz (10.5 dB), the most sensitive hearing range of this species. Such a short duration of noise exposure leads to significant changes in hearing capability, and implies that man-made noise generated from boat engines can have far reaching environmental impacts on fishes.