Auditory Brain Stem Potentials Evoked by Clicks in Notch-Filtered Masking Noise: Audiological Relevance

Abstract

Auditory brainstem-evoked potentials (ABEP) to clicks in notch-filtered masking noise were recorded from 10 adults with normal audiograms and from 10 adults with hearing losses. Masking noise had 0.5-octave-wide notches with central frequencies of 8 000, 2 000, 1 000, 500 and 250 Hz. For each notch frequency, decreasing-intensity series in 10-dB steps (for both the click and the noise) were derived until the detection threshold of ABEP was reached. From the detection thresholds of normal subjects, the normative detection threshold for each frequency was calculated. Deviations from the normative detection thresholds were considered ABEP estimates of hearing loss. The results of this study showed that while ABEP to clicks in notched noise were sensitive to hearing losses, correlations between audiometric hearing loss and ABEP estimates of hearing losses at specific frequencies were nonsignificant. At the present stage of the procedure, ABEP to clicks in notched noise cannot estimate hearing thresholds at specific frequencies.

Key Words:

• Auditory brainstem
• Evoked potentials
• Objective audiometry
• Clicks
• Filtered masking