Infovox iVox for Mac

From AssistiveWare:

Infovox iVox provides Mac OS X users with the best text-to-speech voices ever on the Mac. You won't believe your ears hearing these natural-sounding voices, available in many different languages. What is more, they can be used in any Mac OS X application that uses speech.

The Infovox iVox voices, once installed on the computer, appear in the Speech panel of the System Preferences and can be used by any application that has speech functionality, including Preview, TextEdit, Mail, Microsoft Word (through its Speech toolbar), VisioVoice, Proloquo, GhostReader, Acrobat, AppleScript, Automator, Kurzweil 3000 for Macintosh (version 3.0.4. and higher), TextHelp Read and Write Gold for Mac (version 2.1 and higher) and many others.

You can also use Infovox iVox with Mac OS X built-in speech and accessibility features. Including the Mac OS X built-in VoiceOver screen reader.

Infovox iVox includes all voices available for a language of choice. The following languages are available: American English, British English, French, Canadian French, German, Italian, Dutch, Finnish, Flemish, Spanish, American Spanish, Portuguese, Brazilian Portuguese, Norwegian, and Swedish.

Infovox iVox voices are sold per language with each language consisting of one or more male and/or female voices. All languages contain the American English Heather voice as a bonus. American English even includes two child voices. If you want to have multiple languages, you can buy Infovox iVox plus one or more language packs at half price.