DOI: 10.23641/asha.27011461
title: Click- vs. chirp-evoked ABRs (Campbell et al., 2024)

description: <b>Purpose: </b>The auditory brainstem response (ABR) can be elicited by broadband stimuli such as the click and chirp. Differences in the click- and chirp-evoked ABR have been extensively described using subjective analyses. The aim of the current research is to determine if subjectively observed differences between the click- and chirp-evoked ABR are also represented in objective signal-to-noise ratio (SNR) measurements obtained from these responses at different stimulus intensities and sweep counts.<b>Method: </b>ABRs were collected using click and chirp stimuli on nine adults with normal hearing sensitivity. Three SNR methods (split-sweep average–based SNR [SSA-SNR], <i>F</i> ratio–based single-point [Fsp], and multipoint [Fmp]) were used for the objective analysis of the waveforms at four stimulus intensities (20, 40, 60, and 80 dB nHL) and five sweep counts (100, 200, 300, 400, and 500 sweeps).<b>Results: </b>SSA-SNR measurements were statistically stronger for chirp- as compared to click-evoked ABRs. Additionally, chirp/click SSA-SNR, Fsp, and Fmp ratio measurements were consistently greater than 1. The advantage associated with the chirp was most noticeable at moderate stimulus intensities for all three measurements.<b>Discussion: </b>The advantages for the chirp observed here could have implications for threshold estimation and screening ABR tests. Furthermore, when stimulus intensity and sweep count were varied, general response trends suggest that the three SNR-based methods performed similarly to each other, as well as to traditionally used subjective measures, suggesting that these techniques have the potential to be used effectively in clinic.<b>Supplemental Material S1.</b> Descriptive statistics of Wave V latency as a function of stimulus type and intensity.<b>Supplemental Material S2.</b> Descriptive statistics of Wave V peak-to-peak amplitude as a function of stimulus type and intensity.<b>Supplemental Material S3.</b> Significant Bonferroni-corrected comparisons for SSA-SNR as a function of sweep count.<b>Supplemental Material S4.</b> Significant Bonferroni-Corrected Comparisons for SSA-SNR as a function of intensity.<b>Supplemental Material S5.</b> Significant Bonferroni-corrected multiple comparisons for SSA-SNR as a function of sweep count and intensity (chirps only).<b>Supplemental Material S6.</b> Chirp/click SSA-SNR.<b>Supplemental Material S7.</b> Significant Bonferroni-corrected comparisons for Fsp as a function of sweep count.<b>Supplemental Material S8.</b> Significant Bonferroni-corrected multiple comparisons for Fsp as a function of sweep count and intensity.<b>Supplemental Material S9. </b>Chirp/click Fsp.<b>Supplemental Material S10.</b> Significant Bonferroni-corrected comparisons for Fmp as a function of sweep count.<b>Supplemental Material S11.</b> Significant Bonferroni-corrected multiple comparisons for Fmp as a function of sweep count and intensity.<b>Supplemental Material S12.</b> Chirp/click Fmp.Campbell, M., Delgado, R. E., Ananthakrishnan, S., & Peitsch, K. (2024). Effects of stimulus intensity and sweep count on the click- and chirp-evoked auditory brainstem response. <i>Perspectives of the ASHA Special Interest Groups, 9</i>(5), 1331–1342. https://doi.org/10.1044/2024_PERSP-24-00097