Hemodynamic and hormonal changes induced by noise.

Eighteen healthy male volunteers with normal hearing were exposed to industrial noise at different sound levels (75, 85 and 95 dB A) in a noise laboratory. Blood pressure, heart rate, stroke volume and cardiac output were recorded with noninvasive techniques. Adrenaline and noradrenaline concentration in venous plasma were analyzed before and during noise exposure. The mean resting blood pressure of the whole group was 120/70 mm Hg. During noise stimulation diastolic blood pressure increased (12.2%, p less than 0.001) as did mean arterial pressure (6.6%, p less than 0.001) and total peripheral resistance (12.7%, p less than 0.001). Stroke volume (7.3%, p less than 0.001) and cardiac output (5.0%, p less than 0.01) were both reduced at 95 dB A. Heart rate and systolic blood pressure did not change significantly. At 75 and 85 dB A there were similar but smaller changes in the hemodynamic parameters. There were no changes in adrenaline and noradrenaline in plasma during maximal noise exposure. The noise induced hemodynamic changes remained 5 minutes after the noise stimulation was stopped but had disappeared after 10 minutes of rest.