Comparative responses of rabbits and rats to elevated noise

New Zealand white rabbits and Wistar rats were exposed, in an acoustic chamber, to 1.5 hours of white noise per day at intensities of 107--112 decibels. Compared to the control condition of 60 decibels (background noise level), both rabbits and rats displayed increased adrenal weights (p less than 0.05). Rabbits also had decreased spleen and thymus weights (p less than 0.05). Rats had increased total leukocyte counts and a relative eosinopenia (p less than 0.05). Also, noise exposed rats exhibited a decrease (p less than 0.05) in food intake by the third day of noise exposure. There were no observed changes in hematocrit or plasma protein concentrations.