Kiessling J, Althaus V
Arch Otorhinolaryngol. 1981;230(2):149-59.
Twenty ears of normal-hearing subjects are investigated as to the influence of highpass filtering on latency, amplitude, and shape of auditory evoked brain stem potentials. For this purpose, three different Bessel-filters (steepness 24 dB/octave) with lower cut-off frequencies at 100, 200, and 300 Hz (3-dB down points) and an upper cut-off frequency at 3 kHz are used. Spectral composition of brain stem potentials is analyzed by digital filtering based on Fast Fourier Transformation. Results show decreasing latency and amplitude of the negative wave between Jewett V and VI with increasing lower cut-off frequency. With higher edge frequencies we find attenuation of wave V relative to wave IV amplitudes. For that reason we must assume that an essential part of brain stem activity is located below 300 Hz. In our experience moderate highpass filtering seems to be useful in neurological cases to eliminate low frequency components of the signal. In that way potentials I -- V are easy to be identified and interpeak latencies can be determined without any problems. For objective threshold determination, however, brain stem potentials should be derived preferably with broadband filter settings to improve correlation of tone audiometric hearing loss (at about 3 kHz) and brain stem response threshold. A filter set with different lower cut-off frequencies has proved to be really useful in routine work. However, it must by taken into account that highpass filtering means an alteration of the original response in any case.
对20名听力正常受试者的耳朵进行了研究，以探讨高通滤波对听觉诱发脑干电位的潜伏期、振幅和波形的影响。为此，使用了三种不同的贝塞尔滤波器（斜率为24 dB/倍频程），其下限截止频率分别为100、200和300 Hz（3 dB下降点），上限截止频率为3 kHz。基于快速傅里叶变换的数字滤波分析脑干电位的频谱组成。结果表明，随着下限截止频率的增加，朱厄特V波和VI波之间负波的潜伏期和振幅减小。随着边缘频率的提高，我们发现V波相对于IV波振幅有衰减。因此，我们必须假设脑干活动的一个重要部分位于300 Hz以下。根据我们的经验，适度的高通滤波在神经病例中似乎有助于消除信号的低频成分。通过这种方式，I-V波很容易识别，峰间潜伏期也能毫无问题地确定。然而，为了进行客观阈值测定，脑干电位最好采用宽带滤波器设置来推导，以提高纯音听力损失（约3 kHz）与脑干反应阈值之间的相关性。一套具有不同下限截止频率的滤波器在日常工作中已被证明非常有用。然而，必须考虑到，高通滤波在任何情况下都意味着原始反应的改变。
