Environment noise is ubiquitous in our daily life. The aim of the present study was to determine the effect of postnatal exposure to moderate-level noise on the auditory object exploration behavior of adult rats by comparing the ability of three groups of rats to locate a sound source in a water maze. Two groups of rats, either in the critical period of hearing development or in adulthood, were exposed to 80 dB SPL interrupted white noise for 8 h per day for two weeks. The control group of rats was not exposed to the noise. The ability of the rats to locate a hidden platform that was situated near a sound source in a water maze was tested starting on postnatal day 77. A continuous improvement in the performance of control rats and rats exposed to noise in adulthood was observed during training, whereas rats exposed to noise at a young age exhibited a significantly worse performance. These findings indicated that long-term exposure of young rats to moderate-level noise caused significant impairment of their auditory object exploration behavior compared to exposure of adult animals to the same moderate-level noise.