I don't have any more time to work on it tonight, but i've got a bit done on the subject.
Here are the values that I am using in the Coupling Audio Controller to trigger slack. Putting it there allows you to use the "Acceleration" controller to tie the sound to the actual coupler movement.
Capture.JPG
A few things to note. One is that that no matter what the Trigger Type, the sound will always trigger when the coupler moves past the Trigger Value. The reason is that no matter if the train is speeding up or slowing down, the coupler is accelerating when it moves. So in reality you only need one sound for both stretch and bunching. The second thing is the Trigger Value. Set it below .1 and you will have some very undesirable machine gun firing effects. You have to play with it to get both the stretch and bunching to work right.
Now, I just need to find a few modifiers to make the sound get louder as the slacking approaches the car you are standing nearest to and then fade as it passes.
The tests were conducted from 0 - 10 mph. Don't know how going faster will affect it.
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