Annunciator hangs when there's no sound support

@tanviash noticed that the alarm system annunciator hangs on a Linux system that lacks sound support.
The initial "Annunciator started" can't be heard, and pushing the "Test" button does not result in "Testing 1 2 3" to be spoken.

Unclear if there is a way to detect that situation in the code to for example log an error message, or if the low-level sound code simply hangs beyond our control.