Venous hum
（重定向自Bruit de diable）
Venous hum is a benign phenomenon. At rest, 20% of the cardiac output flows to the brain via the internal carotid and vertebral arteries. This drains via the internal jugular veins. The flow of blood can cause the vein walls to vibrate creating a humming noise which can be heard by the subject. Typically, a peculiar humming sound is heard in the upper chest near the clavicle.