If a toyota camry makes a humming noise, what could be the problem?

Grinding or low-pitched humming sounds can be a sign of wear and failing parts. A low-pitched humming coming from under the car could mean a failing transmission, worn universal joints, a bad wheel bearing, or a worn differential on Your Toyota Camry. The most common is a bad wheel bearing. A wheel bearing is a set of steel balls held together in a metal ring, called a race. At the center of Your wheels, there is a hollow piece of metal, called a hub. The wheel bearings fit tightly inside this hub, and ride on a metal axle shaft, helping reduce friction when the wheel spins. It can be very dangerous to drive if one of Your bearings is worn out, especially since it may cause the wheel to stop while driving. Additionally, a damaged wheel bearing puts a lot of stress on the hub, the CV joint, and the transmission itself.