正常人中枢掩蔽测试结果分析

目的 :通过对一组耳科正常青年人进行中枢掩蔽测试 ,探讨其发生机制及其对听力学检查所产生的影响。方法 :分别测试有无对侧掩蔽声 (CAS)时的纯音气导听阈 ,比较其在相同频率不同强度的CAS时听阈的变化 ,即中枢掩蔽效应 (CME)的大小 ;同时测试相同强度不同频率CAS时CME的大小。结果 :CME具有频率特异性及强度特异性 ,中频 1kHz、2kHz时 ,其CME较低频及高频大 ,其中以频率为 2kHz时最明显 ;CAS强度在6 0dBHL以下时 ,CME随强度增加而增大 ,在 6 0dBHL时 ,2kHz处CME达 (11.5 3± 4 .38)dB ,CAS >70dBHL时 ,则出现过度掩蔽。结论 :因CME的存在 ,纯音听阈测试中 ,如所用CAS >4 0dBHL时 ,则需对测试结果进行修正 ;当CAS强度为 6 0dBHL时 ,CAS在 2kHz处产生大于 10dB的CME ,可用于对伪聋的鉴别

An analysis of the results of central masking effect on healthy ears

OBJECTIVE: To investigate the mechanism of Central Masking Effects(CME) and its effects on audiometry measurement. METHOD: The pure tone threshold was measured when the notest ear was masked or was in quiet respectively. We investigated the different results while giving different level maskers at the same frequency, or giving the same masker at different frequencies to find out their rules. RESULT: The CME has frequency-selective properties and sound level-selective properties. The CME appears apparently at 1 kHz and 2 kHz. At 2 kHz, the CME get the highest. When the masker was lower than 60 dB HL, the CME became higher as the masker was tuned higher; when the masker was 60 dB HL, the CME get the highest(11.53 +/- 4.38)dB HL]. If the masker was higher than 70 dB HL, overmasking appeared. CONCLUSION: Our observations come to the conclusion that central masking correction should be made clinically when the masker is higher than 40 dB HL. 60 dB HL masker at 2 kHz can make the CME higher than 10 dB HL, thereby can be used to identify false deafness.