High speed truck sounds turning inaudible

[Fluffinator]

Now, if this makes sense, once any of my consists hit +47mph the truck sounds just disappear entirely. Not sure what's causing it, but on one of the custom sessions I created for Midwest grain, all of my trains can hit the 55 mark and have that nice high speed sound flying by on the main line. Not sure what's causing this, or if I'm missing something from the route I'm building, but help please? Normal consist I use for testing would just be a simple UP SD70MAC triple header with ~48 JRPX ACF Centerflow 4 bay's trailing with a 4th UP unit bringing up the rear on the JR Lt. Grey (no terrain) tracks.

Thanks

 

[JCitron]

If you have JR freight cars, then they will produce sounds. Your own consist may not have any sounds associated with the freight cars.

Also, there are some sound bug issues with TS12 especially SP1. That could be part of the issue too. I found that if I click on the menu bar then click back in the main screen, the sounds come back.

John