Effects of low-frequency components and analog filtering on auditory brainstem responses. A comparison of analog and digital filtering.

Analog and digital filtering of ABR (Auditory Brainstem Response) is compared for 20 adults with normal hearing. The result shows that the shape of the ABR is changed by the non-linear phase function of the analog filter (350-1,700 Hz). Peaks IV and V are particularly affected. The result also shows that if peaks IV and V are to be identified with certainty it is sometimes necessary to raise the lower band limit of the filter. This is because the low-frequency part of the ABR interferes with peaks IV and V. The latencies of peaks I to V obtained from ABRs after digital and analog filtering have been compared. This showed small but significant differences.