Communication: Humans Talk. Computers Talk - Smart Home Automation with Linux and Raspberry Pi - page 166

Piecemeal Samples
Most automated train announcements are comprised of individual vocal snippets that are then rearranged into order
by a computer. This provides a great range of possible phrases using a comparatively small set of original samples.
With careful trimming of the sound files, they can sound very humanistic. The problem with this approach is that it is
impossible to introduce hitherto unknown phrases into its lexicon. If you are using a human voice as an alarm clock,
for example, you will know in advance every phrase and part-phrase that could be uttered. In the case of error reports
from a software package, you probably won't, particularly when it comes to filenames and user input. In these cases,
you will probably have to acknowledge when the samples don't exist and revert to Festival.
To create a vocal alarm clock, for example, you first need to consider the samples you will need. This can be
as expansive as you're prepared to record for. Many countries have their own speaking clock service, accessible by
telephone, that quote the time in 10-second intervals with many recording an entire 24-hour clock with each specific
phrase. You also need to consider how grammatically exact you'd like to be. Does the phrase “1 second s ” annoy you? If
so, you'll need a specific sample for that. You also need to consider personal preferences, such as whether “15 minutes
past” sounds better to your ears than “a quarter past,” and so on.
Personally, I have a list of standard clock phrases that I consider important:

u “the time is”

u “p.m.”

u “a. m.”

u “midnight”

u “o'clock”

u “a quarter past”

u “half past”

u “a quarter to”

All the other times can be comprised of the following phrases:

u “minutes past”

u “minutes to”

u “past”

u “to”

and the numbers 1 through 20, 30, 40, 50, and 60, the latter being needed for the occasional leap second when my
pedantic geek friends come to visit! I also add specific samples for the following to remain grammatically correct:

u “1 minute past”

u “1 minute to”

I can then retrieve the time with the following and piece them together with code:

HOURS=`date +%I`
MINS=`date +%M`