AIMTo compare the thresholds of auditory brain-stem response (ABR) and frequency characteristics in five normal rodent species: CBA, BABL/c, C57BL, KunMing mice and guinea pigs.

METHODSAuditory brain-stem responses in four species of mice and guinea pigs were investigated with IHS-SmartEP 3.91 system. The thresholds and characteristics of ABR in each frequency were measured by the stimulated sound of tone-pip. Acoustic frequency-threshold curves in these five rodent species were made. The optimal response frequencies were assessed.

RESULTSThe thresholds of guinea pigs were the lowest in five rodent species, and KunMing mice, CBA mice, BALB/c mice, C57BL mice in turn. All the thresholds of ABR in these experimental animals were the lowest in 10 kHz. The thresholds became increasing in higher frequency (> 10 kHz), and in lower frequency (< 10 kHz). This was a common characteristic in frequency threshold curves of ABR in these five rodent species.

CONCLUSIONThe hearing of guinea pigs was the best in these five rodent species. The hearing of KunMing mice was sharper than those of the other mice. Stimuli of 10 kHz was the optimal frequency in these live rodent species, and the optimal frequency range was from 8 kHz to 24 kHz.