Final answer:
The acoustic vibration device is used during a nonstress test to elicit a fetal heart rate response.
Step-by-step explanation:
The acoustic vibration device is used during a nonstress test to elicit a fetal heart rate response. The device uses ultrasound, which is a medical imaging technique that uses high-frequency sound waves to generate an echo signal. By monitoring the fetal heartbeat, the device can provide information about the health and well-being of the fetus.