Whence comes the noise of a DC electric motor?

In my tool collection, I have a Dremel, and a shop vac. Each uses a conventionally commutated DC motor. Each is also as noisy as hell. Why?

Is it:

mechanical noise from the brushes riding on the commutator

arcing at the brush-commutator connection

magnetostriction as the current in each winding loop is suddenly switched on/off when the brushes make/break contact

high-frequency torque spikes as each winding suddenly starts/stops making torque

…something else?

In fiddling with brushless DC computer fans, I have noticed that there is mechanical noise that is apparently related to the torque spikes of each stator winding being suddenly turned on/off resulting in jerky rotation of the magnetic field that drives the rotor (as opposed to the smooth field rotation one achieves in a synchronous AC motor). If I put a brushless DC motor of suitable RPM and power rating in my shop vac, would those torque spikes manifest as the same sort of noise that I currently see? Or would it run much quieter?

IMHO, most of the noise comes from the crappy bearings.

I’ve taken to lubricating the bearings in my Dremels when they get too loud, and it helps a lot. Also, there is a fan in the Dremel, and that probably makes quite a bit of noise, too.

I bet most of the noise is the rotation of the irregular core and windings, plus the little propeller, relative to the air. Like in a jet engine.