Time- and intensity-dependent low-pass filtering of auditory brain stem responses.

A new method of filtering auditory brain stem responses (ABR), which is time-and intensity-dependent, is proposed. The epoch containing the averaged response is divided up into 128 overlapping segments and each segment is differently filtered. The characteristics of a filter that is applied to a segment of the response are derived from the time-dependent spectral composition of normal ABRs at the appropriate stimulus intensity. After filtering, the segments are added together to yield a response with no significant amplitude and/or phase distortion, and with distinctly pronounced peaks that are excellently suitable for evaluation with an automated system.