Analog and Digital Filtering of ABR

Abstract

Objective. In audioneurological evaluations, peak latency is an important parameter regarding the determination of possible wave delays. Digital filtering entails suppression of less informative lowfrequency components without phase distortion, thus accentuating the peak readings. Ipsi-and contralateral recordings have improved the reliability as regards the identification of ABR waves. This applies specifically to the wave IV-V complex. The purpose of this study has been to compare 1) analog and digitally filtered waveforms and 2) ipsi-and contralateral derivations.Design. Two-channel ABR data were collected from 120 unselected subjects referred for assessment of possible retrocochlear diseases. The analog filter bandwidth was 30 to 3000 Hz. Each response was subsequently digitally filtered with a bandwidth of 300 to 2500 Hz, and a comparison of wave identification between the analog and digitally filtered responses was performed. Wave identification was also compared between the digitally filtered ipsiand contralateral responses, and the differences of the wave latencies between the two derivations were calculated. Results and Conclusions. Digital filtering improves