Realistic speeds on inclines

[JWRStation]

I have a number of Locomotives fitted with TTS sound. My layout has numerous continuous circuits with three having inclines of various gradients. There is nothing more monotonous than having sound locomotives running around the circuits with a continuous speed and thus sound. In real life locomotive speeds vary depending upon gradients. In order to try and replicate this I have been experimenting with the PID setting. Changing them slightly did not have any effect and in fact I had to drop them down 1 for each value in order to get a noticeable effect. I did try both at 0 which give an improved speed variation but it was a bit erratic. Finally I found that p=0 gave the best speed variation with i=1 enough to ensure the speed recovered to the set point once on the flat.

From this I can now have a few TTS locos running with various speed sounds moving up and down as loco's traverse around the layout so it is no longer just a continuous and sometimes annoying background noise.

Anybody else looked at this????