ABR Wave I is enhanced with 4 kHz chirp compared to traditional broadband click.

The Wave I of the Auditory Brainstem Response (ABR) has been increasingly proposed as a potential neural marker for subtle auditory-neural deficits. However, the existing standard click-evoked ABR protocols in humans are limited due to reduced amplitude and increased inter- and intra-subject variability of the recorded Wave I. Thus, there is a growing need for developing ABR protocols that could enhance the Wave I amplitude and reliability. To this end, in the current study, we compared a 4 kHz rising chirp with a conventional broadband click, each presented at suprathreshold level (i.e., 70 dB nHL) in 38 young adults with clinically normal hearing. Two within-session repetitions for each stimulus were recorded and Wave I peak-to-trough amplitude, peak to zero amplitude, peak latency, Wave I/V amplitude ratios, and within-session reliability (for amplitude and latency) were evaluated. Compared to click, the chirp produced significantly larger Wave I amplitudes but later Wave I latencies. Within-subject, within-session reliability was also higher for the chirp as compared to the traditional click. However, differences in effects between stimuli were not found for Wave V, though click latencies were modestly earlier than chirp. These findings suggest that a 4 kHz chirp stimulus may be a more viable stimulus for Wave I elicitation than standard click. This preliminary finding exhibits potential for future use of 4 kHz chirp stimuli in clinical evaluation for subtle auditory-neural deficits that otherwise may not be detected through standard electrophysiological measures.