Sex Differences in Auditory Brainstem Responses in the Hispid Pocket Mouse (Chaetodipus hispidus)

The hispid pocket mouse (C. hispidus) is a solitary semi-fossorial rodent that has been the subject of various ecological and genetic studies. However, no previous studies have characterized its hearing ability, which is important for its survival and fitness. We collected auditory brainstem responses (ABRs) from C. hispidus and measured craniofacial and pinna morphological features to assess hearing ability and test differences in hearing thresholds, monaural and binaural ABR amplitudes and latencies between the sexes. ABR recordings revealed that similar to other small mammals, C. hispidus displayed the lowest threshold to sounds between 8-16 kHz, indicating best hearing across those frequencies. We found significant differences in auditory thresholds of the ABRs between the sexes, with females showing lower frequency hearing compared to males. However, no significant differences were detected in monaural and binaural ABR amplitudes and latencies between the sexes. We also found no significant differences in craniofacial and pinna dimensions between the sexes. These findings shed novel insights into the auditory systems across species and highlighted for the first time sex differences in auditory thresholds for this rodent species.