One of the easiest ways to create phrases for AtariVox is to use the PhraseALator utility. PhraseALator is provided free of charge by the folks who create the SpeakJet chip in the AtariVox, Magnevation.
Using a TTL level serial port, you can connect your AtariVox to your PC and pull it's strings from a nice point-and-click interface.
You can use Phrasealator to lookup words in a dictionary and play them back, or you can use it to compose your own words; single-clicking on any of the phoneme buttons will preview the sound of the phoneme, and double-clicking on the button will add the phoneme to the current phrase.
PhraseALator is a closed source program for Windows, and my main platform is Ubuntu, so I decided to create a similar program that could run under Unix type OSes. Speakalator uses GTK for the GUI and standard C Unix libraries, so it should be quite portable.
As a bonus, batari kindly allowed me to incorporate code from his word to phoneme utility, so speakalator can make a best guess at words that aren't in the provided PhraseALator.dic dictionary.
A Linux x86_64 binary is included, otherwise you'll need to build from source.
The program expects the included speakalator.glade and PhraseALator.dic files to be in the current working directory when it runs. In the present version there isn't a config file, so the serial settings aren't saved from session to session.