噪声暴露不同时程中大鼠ABR及DPOAE的变化

目的:研究在长期间断性噪声暴露的不同时程中大鼠听觉脑干诱发电位（ABR）和畸变产物耳声发射(DPOAE)的变化特点，寻找导致暂时性阈移的最小暴露时间以及长期噪声暴露过程中的敏感客观评价指标。方法:将42只成年Wistar大鼠随机分为7组，分别暴露于115 dB SPL宽带噪声下3、6、9、12、15和21 d（给声12 h/停声12 h），噪声停止后24 h和6周分别测定ABR和DPOAE，同时与对照组进行比较分析。结果：所有的暴露组中，ABR的阈值都高于对照组P<0.005）；ABR阈值与暴露时程逐步回归分析：24　h-click y=0.79x+83.81,R²=0.24; 24 h-TB y=1.26x+90.76 ,R²=0.40; 6 weeks-click y=1.26x+69.37，R²=0.32; 6 weeks-TB y=1.41x+82.33，R²=0.30；DPOAE只是在声暴露的早期有明显的变化，第3天和21天暴露组的幅值之间差异无显著性（P>0.05）。结论：随着噪声暴露时间的延长，听力下降恢复的可能性越小；引起暂时性阈移的最少噪声暴露时间是在3 d之内；ABR比DPOAE更能体现声损伤时程的变化情况，是研究长期噪声暴露的敏感客观指标。

Effects of various durations of noise exposure on auditory brainstem response and distortion product otoacoustic emissions in rats

Objective To investigate the shortest exposure time resulted in temporary threshold shift and a sensitive objective evaluated method in long-term noise exposures, through exploring the effect of various durations of noise exposure on auditoiy brainstem response (ABR) and distortion product otoacoustic emissions (DPOAE) in Rats. Methods Forty-two Wistar rats were divided into seven groups randomly; they were exposured to 115 dB SPL broad-band noise (12 h on/12 h off) for duration of 3, 6, 9, 12, 15 and 21 days and the ABR and DPOAE 24 h after cessation of the noise and again after a period of 6 weeks were tested. Results ABR thresholds were significantly elevated in all exposure duration groups (P<0. 005). The results of linear regression analysis between ABR threshold and the duration of noise exposure were as follows: 4 h-click y=0. 79x 83. 81, R2 =0. 24; 24 h-TB y=1.26x 90. 76, R2 =0. 40) 6 weeks-click y=1. 26x 69. 37, R2 =0. 32; 6 weeks-TB y=1. 41x 82. 33, R2 = 0. 301 DPOAE response only showed significantly changes in early exposure duration. The magnitude of DPOAE in 3 d group was not significantly compared with that of 21 d group. Conclusion The longer is the time of noise exposure, the smaller of the possibility for the hearing to regain. The shortest exposure to noise that induced TTS is within three days; ABR seems more sensitive to noise exposure duration than DPOAE.