用脑干电位的互相关函数客观估计听力阈值

CROSS CORRELATION FUNCTION OF BAEP FOR OBJECTIVE ASSESSMENT OF HEARING THRESHOLD

将脑干诱发电位记录分为大小相等的两个子集均,求其互相关函数。互相关函数在原点附近的平均幅度作为估计听力阈值的参数,并通过实验得出表达该参数与阈上刺激强度关系的直线回归方程,从而求出听力阈值的估计公式。把三种阈上刺激强度下的参数值分别代入估计公式,平均结果作为听力阈值的估计。对8个有不同听力损失的病耳进行了估计,其结果与主观阈值平均相差4.6dB。

Brainstem auditory evoked potentials (BAEP) recorded were equally divided into two subensembles and a cross correlation function R (λ) was calculated for them. The average amplitude of R (λ) around λ=0 was chosen as the criterion for hearing threshold measurement. A linear regression equation which represented the relationship between the criterion and stimulus intensity above threshold was obtained on 21 normal and abnormal ears and thus a equation for assessment of hearing threshold was derived. When the equation was applied to ears to be evaluated, the criteria obtained at three different stimulus intensities above threshold were put into the equation and the mean value was calculated for assessment of hearing threshold. The results from 8 ears with different degrees of hearing loss demonstrated that the differences between estimated thresholds and corresponding subjective thresholds are 4.6 dB on the average.