This is the first time I write on the forums, although I am a very old (offline)racer on LFS.
I believe that the gear whine noise should still be heard when we press the clutch and the car is still moving with a selected gear. It should stop only we select neutral. When we have a gear selected and we press the clutch the gears in the gearbox still rotate fast, at the speed of the wheels, so they still make noise.
Hope I helped... and sorry for my bad English
FGED GREDG RDFGDR GSFDG