骨导听觉脑干电反应测试中掩蔽噪声的应用

目的　探讨骨导听觉脑干电反应(auditory brainstem response，ABR)测试中对侧耳适宜的掩蔽强度。方法　对16位正常受试者进行骨导ABR检测及观察刺激侧和对侧白噪声掩蔽对其波形的影响，并对一耳听力正常、另一耳重度感音神经性聋的5位患者进行验证。结果　正常人当同侧或对侧耳加以白噪声掩蔽时，骨导ABR波形和Ⅴ波潜伏期与未加掩蔽时不同。在单侧感音神经性聋患者，患侧给予60dB骨导刺激诱发的骨导ABR可被对侧40dB的掩蔽白噪声所消除。结论　一侧骨导声刺激可使双侧耳蜗兴奋产生双侧ABR，因此检测时必须在对侧耳加以气导掩蔽声，如用白噪声掩蔽时，掩蔽声的强度以比骨导刺激声低20dB为宜。

Application of Masking Noise in Bone- Conducted Auditory Brainstem Response

Objective This experiment was designed to investigate the optimal masking noise onthe contralateral ear in the measurement of auditory brainstem responses evoked by bone- conducted a-coustic stimulations. Methods The air- conducted ABR and the bone- conducted ABR were mea-sured in 16 persons with normal hearing and 5 patients with unilateral profound sensorineural hearingloss to observe the influence of ipsilateral and contralateral masking on the bone- conducted ABR. Re-sults The waveform of bone- conducted ABR was the same as that of air- conducted ABR, but the re-sponse threshold of wave Ⅴ in the former was higher than that in the latter and the latency of wave Ⅴ inthe former was longer than that in the latter. The waveform and latency of wave Ⅴ in bone - conductedABR varied when masking (white noise) was applied on the ipsilateral or contralateral ear. Conclu-sion The waveform of bone - conducted ABR was stable as air - conducted ABR. Excitation in bothcochleae could be caused by bone- conducted acoustic stimulation on one ear, and the ABRs from bothcochleae were evoked. Therefore, it is necessory to mask the contralateral ear while testing bone- con-ducted ABR. The intensity of 20dB less than that of bone- conducted stimulation may be the most suit-able if white noise is selected as masking noise.