电刺激诱发豚鼠耳声发射及其畸变产物

Electrically Evoked Otoacoustic Emissions and Their Distortion Products in Guinea Pigs

为了了解活体耳蜗外毛细胞的电能动性及其耳蜗的微机械作用，用声频范围内的正弦交流电对豚鼠耳蜗行蜗外电刺激，用麦克风记录豚鼠外耳道的声压级，用ＦＦＴ 谱分析仪分析并记录电诱发耳声发射（ＥＥＯＥ）及其畸变产物（ＤＰＥＥＯＥ）。结果，１８ 只豚鼠中１５ 只豚鼠在３～３３ ｋＨｚ 范围内记录到ＥＥＯＥ，频率传递函数示８ｋＨｚ～３１ｋＨｚ 频率范围的反应比较平坦。当Ｆ１＝ ６ｋＨｚ，Ｆ２＝ ７２ｋＨｚ，刺激强度大于１００ μＡ 时，可记录到清楚的ＤＰＥＥＯＥ，当刺激强度达到３００ μＡ 时，除可记录到２Ｆ１Ｆ２ 外，还可记录到另外两个畸变产物：Ｆ２Ｆ１、（２Ｆ１Ｆ２）Ｆ１。输入输出函数曲线表明，在低强度电刺激时，ＥＥＯＥ和ＤＰＥＥＯＥ输入输出函数曲线呈线性，而在高强度电刺激时，两者均呈压缩非线性。由此得出结论：ＥＥＯＥ 和ＤＰ ＥＥＯＥ 是电听觉的表现，具有宽的频率响应范围、动态范围和非线性特征，是研究外毛细胞电机械特性和Ｃｏｒｔｉ器整合功能的良好工具。

The objective of this study was to investigate micromechanical properties and electromotility of cochlear outer hair cells in vivo. Extracochlear electrically stimulation with sinusoid alternating current was delivered to cochlea of guinea pigs. Sound pressure level was recorded from ear canal by microphone and the electrically evoked otoacoustic emissions(EEOE) and their distortion products(DPEEOE) were analyzed with FFT spectrum analyzer. The EEOE in 3kHz to 33kHz were recorded from 15 guinea pigs in 18 guinea pigs, the transfer function was more smooth in 8kHz to 31kHz. The DP EEOE were very clear when F 1=6kHz,F 2=7.2kHz, and the current intensity higher than 100μA. While the intensity increased to 300μA, two distortion products, F 2 F 1 and 2(2F 1 F 2) F 1, could be seen in addition to 2F 1 F 2. The input output function showed that EEOE and DP EEOE I/O function were linear when lower electric intensity stimulation was given, but they displayed compress non linear features when higher intensity current was delivered. The authors conclude that EEOE and DP EEOE are expression of electrophonic hearing characteriged by wide frequency bandpass appearance, wide dynamic range and non linear features, so they are good tools for studying the mechanical properties of outer hair cells and the integrate function of Corti's organ.