诱发性耳声发射的掩蔽

３４例听觉正常受试者（共４８耳）进行疏波短声诱发性耳声发射（ＥＯＡＥ）掩蔽实验，项目包括同侧同时掩蔽、同侧后掩蔽和对倒后掩蔽。同时掩蔽的掩蔽声是稳态白噪声，后掩蔽的掩蔽声是宽带噪声。同侧同时掩蔽强度达３０ｄＢＳＬ时，未观察到对ＥＯＡＥ的掩蔽效应，但对主观听觉感受有掩蔽作用，表明ＥＯＡＥ的客观属性反映听觉行为有其局限性、同侧及对侧后掩蔽出现掩蔽效应时的掩蔽强度分别为３０和５０ｄＢＳＬ，掩蔽阈约分别为５９和６８ｄＢＳＬ。耳蜗的机械特性－非线性或耳蜗内存在的某种功能性的反馈调节系统可能是同侧后掩蔽的作用机理。下行的对侧橄榄耳蜗内侧束对外毛细胞主动收缩的抑制性作用，可有效解释对倒后掩蔽的ＥＯＡＥ变化。

EFFECTS OF MASKING ON EVOKED OTOACOUSTIC EMISSIONS

Effect of ipsilateral and contialateral masking on rarefaction click evoked otoacoustic emissions (EOAE) were analyized in 34 normal subjects (48 ears). There were both simultancous and backward masking for ipsilateral cars and only backwand masking for contlalatelal ears.The simultaneous masker was white noise and the backward masker, wide-band noise. At levels of masker below 30 dB SL the simultaneous masking effat was non-significant for the emissions, but significant for behavioural responses, this indicating the limitation of EOAE in representing auditory behaviour. Effed of ipsilateral backward masking on the emissions appeared to be significant at 30 dB SL, effect of contralateral backward masking, at 50 dB SL.Masking thresholds were about 59 and 68 dB SL, aspdrively, for ipsilateral and contralateral barkward masking. The cochlear mechanical nolilinearity or the physiological fedback inhibition which it may exsit within the cochlca Aught have implications for ipsilateral masking. And that the contralateral medial olivo-cochlcar bundle inhibital outer hair cell activity is necessary for the effective explanation of contralateral masking.