Still with 1.0
But now I actually find out what could cause it
I guess it's the AUTO SLATS unrealistic working on ground.
I noticed every time I heard it, my speed it just around the surface wind speed. and my slats will stay FULL EXT even with Flaps5, if I got lower than 0 kts IAS on ground.
Also same sound could be hear when in air with bumpy ride and AUTO SLATS actually working.

So I think there are 3 bugs with this phenomena:
1. AUTO SLATS should not work when aircraft on ground, regarding the AOA.
2. When AUTO SLATS actually working, there should be no noticeable sound in cockpit.
3. as per FCOM 9.10, control and indication on Leading Edge Transit Light, there is a Note: Light is inhibited during autoslat operation in flight.