Assessment of Acoustic Parameters for DPOAE Detection in Rats: An Initial Step Toward Protocol Development

Distortion product otoacoustic emissions (DPOAEs) are an objective and non-invasive tool for assessing cochlear function and outer hair cell activity. The aim of this study was to evaluate different combinations of acoustic parameters for DPOAE detection in rats, identifying an initial configuration to establish the basis for an efficient and reproducible protocol. Clinically healthy rats were evaluated using a DPOAE recording system with custom-developed stimulus generation and detection software based on Python. Stimuli varied in duration, intensity, and f2/f1 ratio over a 1–20 kHz frequency range, determined by the recording system components. All recordings were performed under dexmedetomidine sedation. For each frequency, distortion product (DP) amplitudes, baseline noise, and signal-to-noise ratios (SNRs) were determined. DPOAEs were considered detectable when the SNR was ≥6 dB. Protocol selection was based on SNR amplitudes compatible with an expected physiological response and on the highest proportion of frequencies with SNR ≥6 dB SPL. The best-performing configuration used an f2/f1 ratio of 1.22, L1=65 and L2=55 dB SPL, and a duration of 1050 ms. These results represent an initial step toward establishing an efficient and reproducible DPOAE detection protocol in rats and provide a basis for its future application as an objective tool for assessing cochlear function in veterinary medicine.