相位谱结合功率谱分析在听性脑干反应阈值客观自动化测试的应用

RESPONSE THRESHOLD DETECTION OF AUDITORY BRAINSTEM RESPONSE BY PHASE SPECTRAL ANALYSIS TOGETHER WITH POWER SPECTRAL ANALYSIS

目的：建立能够进行听性脑干反应（ＡＢＲ）阈值客观自动化测试的方法。方法：采用Ｆｒｉｄｍａｎ相位谱分析法，即同步度（ＳＭ）测试法，并结合功率谱分析法，对接近阈值强度的４０ｄＢｎＨＬ短声诱发的ＡＢＲ进行频域的有效成分分析。根据实验所得有效成分及相关理论公式ＳＭ＋３бｓｍ，计算出相位谱分析定量ＡＢＲ阈值的参考标准。结果：由２１正常耳实验所得ＡＢＲ有效傅里叶成分为５００～６８０Ｈｚ，则定量ＡＢＲ阈值的标准值是０．１６７。基于建立的阈值标准，相位谱分析定量了测试组３６耳的ＡＢＲ阈值，并与ＡＢＲ时域分析所测阈值进行了比较：谱分析和时域分析阈值相同的有１３耳，其它２３耳阈值不同，但差别仅１０ｄＢｎＨＬ，在本实验测试强度变化步长之内。结论：相位谱结合功率谱分析是一种有效的客观自动化测试ＡＢＲ阈值的方法。

Objective:To develop an objective method for threshold detection of auditory brainstem response(ABR).Methods:Using the synchrony measure(SM)method,a phase spectral analysis described by Fridman,as well as power spectral analysis,ABR elicited by clicks at a stimulus level of 40 dB nHL close to threshold intensity was analyzed to obtain its efficient frequency components.The criterion for determining the response thresholds was based on theoretical values of SM +3бsm of efficient frequency components of ABR.Results:The efficient frequency components of ABR recorded from 20 normal ears were in the frequency range of 500～680 Hz.The criterion calculated for the test data was 0.167.In the experimental group,ABR thresholds obtained by the spectral analysis were compared with those by visual inspection of the waveform.Of the 36 ears,13 had the same values and the rest had different ones,such differences being within 10 dB steps set for a change of stimulus levels in this study.Conclusion: Phase spectral analysis,together with power spectral analysis,is useful for objective detection of ABR thresholds.