@Paul Graf, thanks for looking into this. It would improve the support capability of the website significantly if those were available.
@Boilermaker1, you could certainly download any file from the MTH website and install it, but I bring this up as a long term issue because if Atlas made a sound file with custom announcements for a certain passenger train (F40s, E8s) that MTH had never done then we wouldn't have access to it. It would be better if we could avoid that situation entirely.