In the anesthetized chinchilla and guinea pig with electrodes implanted on the dura near the auditory cortex an averaged response (temporal response) could be evoked consistently by pure tones presented to the ear contralateral to the electrode site.
The response was a triphasic wave with an onset latency of 7 msec. In both animals temporal response thresholds were similar and lowest for the ear contralateral to the electrode site. Chinchilla behavioral thresholds tended to be lower than temporal response thresholds but the discrepancy was usually not greater than 10 dB.
It was concluded that during anesthesia temporal response thresholds determined for the ear contralateral to the electrode site could be used with a reasonable degree of accuracy to monitor auditory acuity in these animals.
Mohsen Djalilian, D. Thane R. Cody. Averaged Cortical Responses Evoked by Pure Tones in the Chinchilla and the Guinea Pig. Arch Otolaryngol. 1973;98(3):196–200. doi:10.1001/archotol.1973.00780020204013