The tonic immobility duration and heterophil to lymphocyte ratio were measured in laying hens that were exposed to specific sound stimuli. In the first experiment, 36-week-old hens of four different breeds were studied. The treatments consisted of a control: 65 dB (background chicken vocalizations and fans) and 90 dB (background noises plus truck, train, and aircraft noises), which they were exposed to once for one hour. There was a significant difference between the noise treatments for the heterophil to lymphocyte ratio. Hens that were exposed to the excessive noise had significant heterophilia and had longer durations of tonic immobility. The results did not differ among the breeds. These results suggest that hens exposed to excessive noise were more stressed and fearful than the control hens. In the second experiment, 36-week-old birds from two different breeds were either maintained as the control (exposed to 65 dB of background noise) or were exposed to classical music and background noises at 75 dB for five hours per day for three days. There were no differences in heterophil to lymphocyte ratio between the control and treated hens. However, there was a difference in tonic immobility. The hens treated with music had longer durations of tonic immobility than the control hens. This suggests that treated hens were more fearful than control hens. The authors concluded that excessive noise is stressful and causes fearfulness in laying hens, and that the addition of classical music to the background noise also induces fear.