Sun W, Ding D, Reyes S, Salvi R J
Hearing Research Lab, SUNY University at Buffalo, Buffalo, NY 14214, USA.
Hear Res. 2000 Dec;150(1-2):137-48. doi: 10.1016/s0378-5955(00)00195-7.
The effects of AC and DC current on spontaneous otoacoustic emissions (SOAEs) were studied in normal chinchillas and chinchillas with selective inner hair cell (IHC) loss. Electrical stimulation was delivered through an electrode on the round window or through an electrode in scala media. SOAE frequencies ranged from 4 to 11 kHz and amplitudes ranged from 13 to 51 dB SPL. AC simulation suppressed SOAE amplitude. The suppression contours had a narrowly tuned, low-threshold tip located above the frequency of the SOAE. AC suppression contours were similar to acoustic suppression contours except that the AC suppression contours lacked a high-threshold, low frequency tail. The lowest threshold of the AC suppression contour was 3.9 microA rms whereas the lowest acoustic suppression threshold was 19 dB SPL. AC stimulation, which induced an electrically evoked otoacoustic emission, interacted with the SOAE to generate distortion product otoacoustic emissions (DPOAEs) of up to 26 dB SPL at 2f(S)-f(AC) (f(S)=SOAE). DPOAE amplitude increased with AC current, but saturated at high levels. DC current steps affected both SOAE frequency and amplitude. Positive current at the round window decreased SOAE amplitude and frequency whereas negative current increased SOAE frequency, but had little effect on amplitude. The effects of AC and DC current on SOAEs in animals with IHC loss were similar to those in normal chinchillas.
研究了交流电（AC）和直流电（DC）对正常毛丝鼠以及选择性内毛细胞（IHC）缺失的毛丝鼠自发耳声发射（SOAE）的影响。电刺激通过圆窗上的电极或中阶内的电极进行。SOAE频率范围为4至11kHz，幅度范围为13至51dB SPL。交流电刺激抑制了SOAE幅度。抑制轮廓有一个狭窄调谐、低阈值的尖峰，位于SOAE频率之上。交流电抑制轮廓与声学抑制轮廓相似，只是交流电抑制轮廓没有高阈值、低频的尾部。交流电抑制轮廓的最低阈值为3.9微安均方根值，而最低声学抑制阈值为19dB SPL。诱发电诱发耳声发射的交流电刺激与SOAE相互作用，在2f(S)-f(AC)（f(S)=SOAE）处产生高达26dB SPL的畸变产物耳声发射（DPOAE）。DPOAE幅度随交流电电流增加，但在高水平时饱和。直流电流阶跃影响SOAE频率和幅度。圆窗处的正电流降低了SOAE幅度和频率，而负电流增加了SOAE频率，但对幅度影响不大。交流电和直流电对IHC缺失动物SOAE的影响与正常毛丝鼠相似。
