What is this noise from the dash? (sound clip posted)

[boyo]

NOTE: I recommend using head phones and turn up the volume when playing the clip

2007 Lexus IS 250

From the passenger side or middle dash area (definitely not driver side) I hear this noise as if a tiny metal ball would be loose and moving to the vibration, see the clip posted below.

It only happens while driving and not during stand-still, the noise gets bigger if the road is not as smooth

This noise only started in recent weeks as the weather got warmer. I definitely did not hear this sound during the winter when it was cold.https://youtu.be/fUUkVpV-lIU

 

[The-Acre]

It just sounds like a plastic rattle from somewhere. Rattles and creeks can be "seasonal" as materials expand and contract with temperature changes. Have you tried asking a passenger to press various parts of the dash as you drive to see if you can locate it?

[Beamish]

 

Wedge a small piece of rubber or some other flexible material between the top of the dashboard and the centre point of the windscreen and see if this helps.

There is a known issue with some of the dashboard fixings.

[Linas.P]

Could it be something in door "pockets"? I remember I had tyre pressure gauge and it drove me mad. Failing that I would look at speaker grill area. 

[NemesisUK]

I chased a rattle for weeks only to find it was a small tin of mint imperials my wife left in the centre armrest cubby