Objective audiometry using positive slow wave of auditory brainstem response

通过1986 ~ 1987年的研究项目，探讨了ABR的顶点正慢波（PSW）的应用潜力。为了评估PSW的频率特异性，我们进行了两个实验。1)采用音调对音调同时掩蔽范式确定大鼠的调谐曲线。构建调谐曲线来定义掩蔽强度，从而导致探头引起的PSW振幅降低50%。Q_<10>值分布在1.0 ~ 1.6之间。调谐曲线的最大掩模频率不一定等于没有2khz的探头频率。2)同样的范式在人类受试者中使用。Q_<10>值随频率的增加而逐渐增大。他们的分布在1.0到5.3之间。拼接曲线的最大掩模频率不一定等于探头的频率。这些结果表明，短音脉冲刺激可以在不同的频率下评估某些听觉功能，并且它们在刺激频率周围的耳蜗区域具有更宽的频率分布。为了获得稳定的人体PSW，我们进行了两次实验。(1)将短音爆发引发的波从与短音爆发持续时间长、起落时间相同的刺激引发的波中减去。结果表明，随着音调爆发持续时间的增加，人类受试者的PSW也被延长。2)采用非头侧参考电极法记录头皮PSW。研究结果表明，PSW的最大振幅出现在C_z附近。A_1和A_2为活性电极，因此，正慢波振幅高于标准顶点-耳垂偏差。ABR阳性慢波在临床应用中存在一些难点问题。然而，该项目的结果表明，它有潜力作为客观听力测量的工具。

Through the present ressearch project from 1986 to 1987, the potential of application of vertex-positive slow wave ( PSW ) of the ABR was investigated.In order to evaluate frequency specificity of the PSW, two experiments were performed. 1) A tone on tone simultaneous masking paradigm was used to determine tuning curves in rats. Tuning curves were constructed to define masker intensity that resulted in a 50% reduction in probe elicited PSW amplitude. Q_<10> values were distributed between 1.0 and 1.6. Maximum masker frequencies of the tuning curves were not necessarily equal to the frequency of probe without 2-kHz. 2) The same paradigm was used in human subjects. Q_<10> values were gradually increased with the increase in frequency. They were distributed between 1.0 and 5.3. Maximum masker frequencies of the tueing curves were not necessarily equal to the frequency of probe. These results indicate that the short tone burst stimuli may enable to assess certain auditory function at different frequencies, and they have wider frequencies' spread of the cochlear area around stimulus frequencies.In order to get stabilized PSW in human subjects, two experiments were performed. 1) The wave evoked by short tone burst was subtracted from the the wave evoked by the stimulus which consists long duration and same rise-fall time as the short tone burst. Its results showed that the PSW recorded in human subjects were also elongated as the duration of a tone burst was increased. 2) The PSW were recorded from the scalp using non-cephalic reference electrode method. The study led us to the conclusion that the PSW were of maximal amplitude at the resion of C_z. A_1 and A_2 are active electrode, thus, amplitude of positive slow wave is higher than that from standard vertex-earlobe deviation.There are some difficult problems in the clinical application of the positive slow weve of ABR. However, the results of the project indicate that it has potential as a tool for objective audiometry.