Tapping sound near window or seat belt

Im uncertain if this has already been addressed, (Im a newbie today) but I have a 2015 Tundra SR5 and very often I'll hear this distant but noticeable tapping sound that seems to be near the window or seat belt on side wall. Does anybody know or heard of this subject and is there a known root cause and solution?

thanks

 

is the noise only noticed when the seat belt is NOT in use?

 

Mine does that when the kids don't put the seat belt away correctly....

 

The rear seatbelts are known to flap in the wind against the pillar.

 

Yup, this is what causes mine in the rear. If talking about front seatbelt area, I've never experienced that one. Or if windows are all up I have yet to hear any tapping.

 

This tapping is near the front driver side seat belt. I hear it both when using and not using the seat belt so maybe something in the door? I hear it more with the windows up or down. Its definitely not the rear seat belts.

 

Interesting. Anyway to video while driving to post it?

 

Im not sure that video would pick up the tap sounds, its not very loud but I could try. To be continued...
thanks