Acoustic Startle Reflex in Chinchilla: Standardized Baseline and Intensity–Frequency Effects for Preclinical Auditory Research

The chinchilla (Chinchilla lanigera) is a valuable model given its human-like hearing range and high sensitivity between 1–8 kHz; however, a species-specific ASR baseline is not yet available. We present a study that standardizes ASR in chinchilla and reports the effects of intensity and frequency as groundwork for implementing, in future phases, gap-prepulse inhibition paradigms (GPIAS). Amplitude and latency were recorded with the Startle Reflex Response system (©MazeEngineers) using 20-ms pulses, intensities between 90 and 115 dB SPL, and four frequencies (1000, 2000, 4000, and 8000 Hz), with randomized presentations and controlled repetitions. Results indicate a consistent increase in startle amplitude with increasing intensity across the tested range, delineating a robust intensity–response function. Response latency remained constant across conditions, suggesting motor gain changes without detectable temporal variations in the reflex pathway. In the frequency analysis, at equivalent intensities, no significant differences were observed in amplitude or latency. These findings provide operational parameters and calibration criteria, define reproducible working windows, and allow estimation of auditory thresholds without timing bias. By establishing this baseline, the study enables the adaptation and validation of GPIAS in chinchilla for the preclinical detection of tinnitus-like behavior and for translational investigations of temporal auditory processing.