Purpose <p>Assessment of cochlear synaptopathy (CS) in humans depends on proxy measures of auditory nerve function; nonetheless, their clinical use fundamentally relies upon measurement reliability. This study assessed the short-term test-retest reliability of various proxy measures of CS across three test sessions.</p> Methods <p>The study employed a quasi-experimental, single-group, time-series design. Thirty adults with normal auditory abilities participated in three test sessions spaced at short inter-session intervals. Measures included absolute auditory brainstem response (ABR) Wave I amplitude, growth function of ABR Wave I amplitude across 60 to 90dBnHL, summating potential to action potential (SP/AP) amplitude ratio, acoustic middle ear muscle reflex (MEMR) threshold, and MEMR strength. Repeated-measures ANOVA (RMANOVA) was used to compare differences across sessions. Reliability was evaluated using intraclass correlation coefficient (ICC), within-subject coefficient of variation (wCV), and standard error of measurement (SEM).</p> Results <p>RMANOVA revealed no significant differences across sessions for most measures, except MEMR threshold for broadband elicitor. Each measure exhibited a unique reliability profile. ABR wave I amplitude showed good to excellent ICC and low SEM, indicating high relative reliability and low measurement error. In contrast, ABR wave I growth slope and SP/AP ratio exhibited moderate to poor ICCs, respectively, relatively high wCV values, and low SEM, reflecting greater within-subject variability and relatively poor reliability. MEMR threshold measures demonstrated higher stability than MEMR strength measures.</p> Conclusion <p>The results indicated that whereas various proxy measures of CS showed good reliability, derived and ratio-based measures are marked by increased within-subject variability, thereby limiting their interpretability and consistency as reliable measures.</p>