Development of absolute auditory thresholds in the house mouse (Mus musculus)

The development of hearing in the house mouse (Mus musculus) was behaviorally tested from the first postnatally measurable thresholds to those of young adults. An unconditioned stop reaction on tones was used in 9- to 11-day-old mice, then an unconditioned pinna reflex that can be elicited at low intensities and is not equal to the Preyer reflex. In addition, thresholds from 17- to 19-day-old and adult mice were obtained by a conditioned eyelid reflex. Frequencies between 1 and 80 kHz were tested. First reactions on tones were found at day 10 after birth in the frequency range of greatest sensitivity in the adults (10-20 kHz). The sensitivity optimum at 15 kHz becomes evident at day 14. Up to day 15 a sensitivity increase is noticeable for frequencies below the optimum, whereas high frequency sensitivity increases up to day 18. A second maximum of sensitivity at 50 kHz is measurable in 2- to 3-month-old mice, the threshold curve of which is defined as the standard for Mus musculus. The present behavioral data can well be correlated with existing electrophysiological results in mice and rats.