| IntroductionThere are many cases involved the degree of injury and the grade of disability because of the auditory obstacles on the living body appraisal in clinical forensic medicine. The various degrees of the auditory obstacles are directly related to judge the cases. But in practice we evaluate the degrees of injury and disability caused by traffic incident. The divide of the degree of auditory injury is basis on the dB decrease of equal number about pure tone of speaking frequency - testing threshold of audibility through air. The patients appear the different phenomena of pretending deafness and aggrandizing the auditory losing. So the methods of objective auditory testing have very important significance in forensic medicine research.In recent years ABR have been widely applied to forensic medicine appraisal as a way of objective auditory test because it is not affected by the subjective consciousness, sleeping of the examinee and the medicament. Behavior threshold of audibility are usually computed with the threshold of V - wave reaction. ABR latent period disappear very quickly just in 1 ~ 2ms. The effective port of sound stimulation, which induces ABR, could not be longer than it and just be wink -sound and short sound in wide frequency. But the short sound is wider and hard to test the relationship between frequency characteristic and intension. So ABR caused by short sound could only provide the information of auditory in higher frequency, but not in lower one. That is to say that the accurateness of results is influenced if ABR is only used in objective auditory testing.Szyfter has approved that 40 Hz AERP threshold volume is closer to subjective auditory threshold than ABR, and that it has well frequency characteristic, and include spoken language auditory threshold of human ears. AERP is sensitive to the auditory losing in low, middle, and high frequency, which could reflect accurately spoken language auditory threshold. So it is an effective evaluation method of auditory threshold that has frequency specialty for auditory obstacle. So it makes up the lack of ABR reflection on low frequency audibility.Now there is very limit about combining 40 Hz AERP and ABR to evaluate the objective audibility. It is also waiting for the further research that how to apply 40 Hz AERP to evaluate auditory obstacles objectively in forensic medicine. For this my research plans to study frequency specialty of 40Hz AERP, relationship with the subjective auditory threshold and significance of the combining use with ABR in forensic medicine. I aim to look for the best way and notice items, which enhance the evaluation scientifically and accurately.Subjects and MethodsIn my test, there are 17 - 53 years old people who are divided into normal group and abnormal group, normal group 40 people (62ears) , abnormal group 20 people (24ears) have experienced pure sound testing and the test of 40Hz AERP and ABR. 40Hz AERP use short pure sound ( Tone) repeated 39. 1 times per second as stimulate sounds. The stimulate frequency are 0. 5k, Ik, 2k and 4kHz, duration 100us, filter the waves 10 ~ 100Hz, repeat 500 times. Using needle electrode, placing record electrode on the center of skull peak, reference electrode on filter mastoid process in test direction and grounding electrode on forehead where is near the hair. Impedance ofelectrode is lower than 5 k, and resistance discrepancy between the e-lectrodes is lower than 3kfl. In examinees 10 people (20ears) received the 40Hz AERP reaction threshold test of 1kHz both under natural sleepjng and waking. ABR sound stimulation use short sound (click) , filter the waves 100 -1500Hz, scan time 9. 8s, duration 100us, repeat 1000 times. Examinees close their eyes; keep quiet and lay on the examining table in the lab room equipped with sound insulation and electric shield facilities.ResultsAbove the 60dB intensions (0. 5 ~4kHz) of sound stimulations are given to 86 ears, as the result 84 ears elicited 40Hz AERP, 82 ears elicited ABR. The test result of 40Hz AER... |
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