In open field behaviour, continuous noise of 85 dB was shown to increase defecation and reduce both social activities and non-social activities (sniffing, grooming or crawling) of rats when compared with 50 dB, 65 dB or 75 dB. Although noise of moderate intensity is commonly present during experiments on animal learning and memory, its impact has not been explored fully (Prior, 2006). Noise-exposed rats made fewer errors, explored less and finished their trials sooner. Results show that the acoustic environment is an important variable in studies with animal models of learning and memory.