Schoonhoven R
ENT Department, Leiden University Hospital, The Netherlands.
Audiology. 1992;31(2):72-86. doi: 10.3109/00206099209072903.
An investigation is presented on the effect of click polarity upon the auditory brainstem response (ABR) in cases of simulated high-frequency hearing loss. A high-frequency hearing loss was stimulated in 12 normal subjects by applying a high-pass noise masker, the noise cutoff frequency being varied in half-octave steps through the range of audiometric frequencies. With this paradigm, the effects of click polarity on the ABR are similar to those reported in patients with high-frequency hearing loss, including changes in waveform morphology and substantial peak latency shifts. To evaluate the role of individual cochlear frequency channels in a more direct way, half-octave narrow-band responses were determined by pair-wise subtraction of the high-pass-noise-masked responses. As far as ABR peak latencies are concerned, stimulus polarity effects tend to increase towards the lower frequency bands. Thus, the selective elimination of the contribution to the ABR of cochlear high-frequency channels can be held responsible for the increased dependence of ABR on click polarity observed in high-frequency hearing loss. However, statistical evaluation of peak I, III and V latencies, both in high-pass-noise-masked and in narrow-band ABRs, reveals that the latency effects are not systematic between subjects. Mechanisms producing the observed rarefaction-condensation differences, possible explanations for the large intersubject variability and the consequences for clinical interpretation of ABR are discussed.
本文介绍了一项关于在模拟高频听力损失情况下，点击极性对听性脑干反应（ABR）影响的研究。通过应用高通噪声掩蔽器，对12名正常受试者进行高频听力损失刺激，噪声截止频率在听力计频率范围内以半倍频程步长变化。采用这种范式，点击极性对ABR的影响与高频听力损失患者中报道的影响相似，包括波形形态的变化和显著的峰潜伏期偏移。为了更直接地评估单个耳蜗频率通道的作用，通过对高通噪声掩蔽反应进行两两相减来确定半倍频程窄带反应。就ABR峰潜伏期而言，刺激极性效应在较低频段往往会增加。因此，耳蜗高频通道对ABR贡献的选择性消除可能是导致高频听力损失中观察到的ABR对点击极性依赖性增加的原因。然而，对高通噪声掩蔽和窄带ABR中的I、III和V峰潜伏期进行统计评估发现，潜伏期效应在受试者之间并不系统。本文还讨论了产生观察到的疏波-密波差异的机制、受试者间巨大变异性的可能解释以及ABR临床解释的后果。
