"Buzzing" sound of pencil: from the ferrule?

Does the buzzing sound a pencil makes when you throw it with a lot of spin come from the nubbins on the ferrule? I notice that when you rotate the pencil faster the pitch gets higher, and my estimations based on pencil rotation speed and number of nubbins in the ferrule is approximately right.

The other hypothesis is the sound is caused by the rotation of the pencil as a whole but the sound appears too high-pitched for this since there are only 6 ridge-changes per rotation whereas in the ferrule, there isusually a crimped space – that photo is lacking on, and you see a completely round empty part of the ferrule instead.

Ahhh…if you have a pencil that looks like the yellow one in the picture, does it still make a buzzing sound when you spin it fast?