My DC/DC is whistling ( TPS5433x )

Hello guys

I'm working on a design based on TPS5433x.
It works pretty well; efficiency, accuracy, load responce,...

But this design makes noise, when his load has periodic transients.
For example, if the load switches form 250 to 500mA every 0.16ms, the inductor whistles.

Inductor's Isat>>Ipeak, so this a not a saturation problem.
I had
- enhance the COMP network.
- change the switching frequency ( 125kHz and 500kHz ).
- test my design with different inductor quality, Shielded or not Unshielded.
It does not change anything.

So I don't know what to do to delete this whistle.
Thanks,