Vibration of the Abdomen in Non-Pregnant Sheep: Effect of Dynamic Force and Surface Area of Vibrator

Vibration exposure is a growing concern for increasing numbers of working pregnant women. The coupling between vibrating machines and the body determines to a great extent the degree of exposure and thus any maternal or foetal morbidity. In the present experiments we determined the effect of dynamic force and surface area of a vibrator on intraabdominal sound pressure level (SPL). Intraabdominal SPL was measured with a miniature hydrophone during mechanical vibration between 1–5000 Hz. Three different dynamic forces: 0.07, 0.14 and 0.42 newtons (N), and actuator head sizes: 2, 8 and 32 cm 2 were used with a constant static force of 9 N. Increasing the applied dynamic force increased the generated SPL (p<0.0001). The different actuator head sizes did not meaningfully affect sound transmissibility across frequencies.