骨导声诱发的耳声发射耳蜗图

OTOACOUSTIC EMISSION COCHLEOGRAM EVOKED BY BONE CONDUCTED STIMULATION

用不同频率的短纯音骨导刺激,在7名(14耳)听力正常受试者同时记录双耳声诱发耳声发射(EOAE)。此法比单耳轮流记录省时一半。研究结果表明,EOAE 为一种窄带声,其中心频率随刺激声频率增高而增高,提示 EOAE 产生部位在接受刺激声频率对应的耳蜗部位附近。EOAE 的潜伏期与刺激强度无明显关系,但有随刺激声频率增高而变短的趋势,可能与不同频率刺激声诱发的 EOAE 在基底膜上产生的部位与鼓膜之间的距离不等有关。除1耳用4.0kHz 外,用1.0,2.0,3.0和4.0kHz 短纯音刺激在14耳全可记录到 EOAE,0.5kHz和6.0kHz 则分别在10耳和7耳记录到 EOAE。0.5—6.0kHz 短纯音诱发的 EOAE 的阈值均值连线所得的声发射耳蜗图上可见,1.0kHz 处阈值最低,而在这些受试者所测得的中耳共振频率平均值为1100±230Hz,推测1.0kHz EOAE 阈值最低与中耳的传导函数有关。本文描述的骨导双耳同时记录 EOAE 并描记声发射耳蜗图的方法可用于临床的听力客观评价。

As bone conducted stimulation,tone bursts of different frequencies were ap-plied through the forehead in 7 normal-hearing subjects.Binaural evoked otoacoustic emissions(EOAE)were then recorded simultaneously,which saved onehalf of the time required for conventional monaural recording.Analysed withautoregressive modeling,the main echo of EOAE was a narrow-band sound witha stimulus dependent central frequency.It was suggested that the generationsite of EOAE was near to that cochlear portion stimulated by the correspondingfrequency.The latency of EOAE,although independent of the stimulus inten-sity,tended to be shorter at higher stimulus frequencies.This was possibly due to the difierences in the distances from the generation sites of the otoacousticemissions to the tympanic membrane Recordable otoacoustic emissions wereevoked by tone bursts of 1.0,2.0,3.0 and 4.0 kHz in all the 14 normal earsexcept one at 4.0 kHz,and 10 and 7 ears by tone bursts of 0.5 and 6.0 kHZ,res-pectively.Emission cochleogram was obtained when the means of EOAE detec-tion thresholds were plotted in an audiogram format.The lowest thresholdwas found at 1.0 kHz.This might be related to the middle ear resonancefrequency of 1100±230 Hz.The technique of simultaneous recording of bi-naural EOAE and plotting of emission cochleogram described in this paper isclinically useful as a means of Objective evaluation of hearing.