From Digital Future:
Digital Future Text-to-Speech SDK is aimed at helping software developers add text-to-speech functionality to their applications. Supported languages: U.S. English, U.K. English, Spanish, French, German, Italian, Japanese, Chinese, and Korean. Officially supported programming languages: C++, Objective-C, Java, C#, Visual Basic.NET, Visual Basic 6. Digital Future Text-to-Speech SDK (DF TTS SDK) is the only true OS native (no COM/ActiveX, no client-server, etc overheads) cross-platform provider-independent technology that provides standardized and unified API's for the implementation of the conversion of text data into speech.
Digital Future Text-to-Speech SDK for supports: 9 languages and over 100 voices; C++, Objective-C, Java, VB.NET, C#, VB 6 (all officially supported); Speech synthesis and control through a unified API;Audio file generation in numerous audio formats; Speech synthesis events. Version 3.5 update API's for cross-platform support.