Sedation Differentially Affects Distortion-product and Stimulus-frequency Otoacoustic Emissions in Chinchillas
Year: 2026
Type: preprint
Abstract: Purpose Otoacoustic emissions (OAEs) are used to assess outer hair cell (OHC) function. Clinical interpretation of OAE responses, however, is often limited to a present/absent binary since both physiological factors and measurement variability affect the measured OAE amplitude. Prior work showed elevated OAE responses in sedated compared to awake chinchillas, pointing to the potential influence of the medial olivocochlear (MOC) efferents on amplitudes, but this finding is inconsistent across species and OAE type. Here, we aimed to further investigate the effect of anesthesia on distortion-and reflection-type emissions in chinchillas using swept stimuli and more reliable calibration methods. Methods Swept distortion-product (DP) and stimulus-frequency (SF) OAEs were measured in chinchillas with and without ketamine/xylazine sedation. Stimuli were presented using in-ear forward pressure level calibrations. DPOAE and SFOAE amplitudes and estimated Q erb from SFOAE group delays were compared across the two conditions. Results We found that low-frequency DPOAE amplitudes were elevated when animals were sedated. The difference in SFOAE amplitudes was more variable across animals but appeared mildly reduced in sedated animals. Q erb estimates were slightly higher in sedated animals at some frequencies. The effect of sedation was not different across sexes. Conclusion Taken together, these findings suggest that sedation impacts OAE measurements in chinchillas. MOC modulation could account for the present findings and differences across species. For diagnostic precision, OAE responses should be considered in the context of not only intrinsic OHC function but also extrinsic physiological processes that can modulate OHCs.
Language: English
Subfield: Sensory Systems
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
Awards: Individualized Profiles of Sensorineural Hearing Loss from Non-Invasive Biomarkers of Peripheral Pathology, Interdisciplinary Training in Auditory Neuroscience, Place and Time Processing of Pitch in the Context of Cochlear Dysfunction, Effects of Sensorineural Hearing Loss on Robust Speech Coding
OpenAlex ID: W7204919140