Doyle D J, Hyde M L
Scand Audiol. 1981;10(2):81-9. doi: 10.3109/01050398109076166.
Auditory brainstem responses (ABRs) to monaural 70 dB nHL clicks in normal adults were recorded with wide bandwidth and stored digitally. Using digital to analogue conversion with expanded time, the ABRs were input to a variable band-pass filter. The order of averaging and filtering was unimportant. Low-pass effects were unremarkable. High-pass filtering in the commonly used range 20 Hz to 500 Hz produced severe waveform distortion, causing emergence of artifactual peaks, amplitude increase and decrease, absolute latency decrease and interpeak interval changes. Digital high-pass filtering gave identical results. The distortion increased with the filter order. Using a zero phase characteristic drastically reduced ABR distortion and abolished latency changes except for poorly resolved peaks. Butterworth and boxcar filter moduli gave identical results. At common high-pass frequencies, filter phase distortion dominated the mean square error in ABR estimation. Off-line digital filtering of ABR is both practicable and desirable, especially for facilitating inter-laboratory pooling of data.
记录了正常成年人对单耳70 dB nHL短声的听觉脑干反应（ABR），采用宽带宽并进行数字存储。通过扩展时间的数模转换，将ABR输入到可变带通滤波器。平均和滤波的顺序并不重要。低通效应不明显。在常用的20 Hz至500 Hz范围内进行高通滤波会产生严重的波形失真，导致伪峰出现、幅度增减、绝对潜伏期缩短以及峰间期变化。数字高通滤波得到了相同的结果。失真随着滤波器阶数的增加而增大。使用零相位特性可大幅降低ABR失真，并消除潜伏期变化，但分辨率较差的峰值除外。巴特沃斯滤波器和矩形窗滤波器模给出了相同的结果。在常见的高通频率下，滤波器相位失真在ABR估计的均方误差中占主导地位。ABR的离线数字滤波既可行又可取，特别是有助于实验室间的数据汇总。
