[TrainChris4460]

Interesting, I have noticed examples of that too.
The sms files, would those be more of where we can adjust and edit how sounds (like the bell and whistle) are triggered?

[Weter]

...as well as volume, pith, priority, dependence on other events or processes.
In MSTS used so-called Scalability groups-the sets of settings for traffic usage (most primitive,so resource-saving), and some "quality-steps", defined by options "Sound Quality" slider's position for best fitting to Your System grade, as they refers more or less sound streams and can use different *.wav-files (with more or less quality, for example) for playing same sound events.

ORTS processes some things more or less different, obvious.
The worst thing in my case-that it's not hear one of the alerter's sounds, so it's very uncomfortable to drive engines, which using that sound-set.
Many times I've investigated this issue, but no result discovered. (if I substitute the alerier.wav by, say, horn.wav, it works) so Is the problem related to *,wav-file itself?