SPI announcement sound files

["Hubert Lam" <hubert@imap4.com>]

As mentioned in subject, these have been replaced by never "DVA" sound files
last Thursday afternoon, except that the station names all have a rising
inflection, not a falling one, which results in a very strange sound when
things like "Hornsby via Town Hall" is announced. It is also a lot slower
than the old messages, and so most of the time the train would have departed
halfway throughout the announcement being played.