Authors: Blandine Duval¹, Laura Breda¹, Charles Vincent¹, Zoe Kaier-Green¹, Jérôme Geoffroy¹, Mathieu Schué¹, Hugo Laullier¹
¹CILCARE SAS
Background: Wave I amplitude is a proposed non-invasive biomarker of cochlear synaptopathy, but established reproducibility is required before clinical use.
Method: Thirty healthy adults aged 18–25 years (19 women) with normal audiometric thresholds (Pure-Tone Average 0.5–4 kHz < 20 dB HL) and normal speech-in-noise performance (SNR < −3 dB) attended up to four electrophysiological sessions two weeks apart. Click-evoked ABRs were recorded at 80 dB nHL with ECG monitoring: three sessions by the same tester, one by another tester. Test–retest reliability of Wave I amplitude and latency was evaluated, and sources of measurement variability, including head size, cardiac and respiratory parameters, and tester effects, were examined.
Results: An SNR-based quality threshold retained ~90% of recordings. Reproducibility was higher for Ear-canal than Mastoid recordings (ICC = 0.86 [95% CI: 0.77–0.90] vs. 0.77 [0.68–0.84]; CV 12–14%). Latency showed excellent agreement (CV 2–3%). Adjusting amplitude for head size and residual noise reduced the central 95% range by 18%, although the distribution remained wide. Tester-related variance remained below residual within-ear variance across all conditions.
Conclusion: Wave I measures show good within-individual reproducibility, supporting longitudinal monitoring. Tester variance was not the dominant source of variability, and the empirically derived SNR threshold and normalization approach provide actionable tools for future multi-tester studies.
