Frequency-specific Threshold Estimation Values Using Auditory Brainstem Responses in Healthy Adult Male Rats

Document Type : Original article

Author

Department of Audiology, School of Rehabilitation, Shahid Beheshti University of Medical Sciences, Tehran, Iran.

10.32598/SJRM.14.6.3408

Abstract

Background and Aims Auditory brainstem response (ABR) is an objective, electrophysiological test that has been used to assess auditory function for nearly 50 years. Rats are one of the most widely used rodent species for laboratory studies of the auditory system, which requires standardization for ABR recording in each laboratory. The aim of the present study was to estimate hearing thresholds using ABR and tonal stimuli at octave frequencies in healthy adult male Wistar rats.
Methods In this experimental study, 8 adult male Wistar rats were subjected to ABR measurements using a threshold estimation approach under ketamine/xylazine anesthesia, in accordance with the principles of working with laboratory animals. Tone burst stimuli were presented at octave frequencies of 2000 to 16000 Hz through an appropriate loudspeaker, and the threshold of tonal stimuli was recorded in a descending manner by tracking wave II. Data were analyzed using SPSS software, version 17 and one-way analysis of variance.
Results The mean thresholds obtained at tonal frequencies of 2, 4, 8 and 16 kHz were 21.25±4.43, 10.27±2.67, 6.87±2.58, and 2.31±3.75 dB SPL, respectively. A statistically significant relationship was observed between the threshold values and the frequency evaluated (P<0.001).
Conclusion An inverse relationship between the frequency of the tonal stimulus and the estimated values of ABR thresholds was observed in rats, which can serve as a basis for the extent of threshold changes in pathological conditions leading to hearing damage in animal models.

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Volume 14, Issue 6
January and February 2026
Pages 970-979
  • Receive Date: 28 September 2025
  • Revise Date: 05 October 2025
  • Accept Date: 05 October 2025
  • First Publish Date: 05 October 2025