Actually, since the chuffs have been generated by the tach pulses, the drivers have never been in sync with the sounds. Yes, there is a fairly accurate number of chuff/rev, but as far as when the chuff sound is generated, that isn't synchronized to the position of the drivers or cylinders. Back in the old days with the chuff switch on an axle cam, it would have been possible to get them in the correct point in the driver rotation.
However, the articulated sounds have always been generated artificially.
