A study of methods used to enhance wave I in the auditory brain stem response.

Auditory brain stem responses (ABR) were recorded in 15 audiometrically and neurologically normal adult subjects. The purpose of the study was to investigate various aspects of stimulus composition (intensity, click rate, and polarity) and response measurement parameters (band-pass filtering and electrode linkage) that might serve to enhance detectability of wave I in the ABR. Amplitude of wave I was significantly enhanced by an increase in intensity, a decrease in click rate, and use of a negative (rarefaction) polarity click. Amplitude of wave I was not significantly influenced by bandwidth of the response filter or by a horizontal (mastoid-to-mastoid) electrode linkage. Use of simultaneous response acquisition from an ipsilateral and contralateral reference electrode array did aid in the detection or visualization of wave I, particularly for lower stimulus intensity levels or faster click rates.