By calling the GetSpeechInfo function with the soSynthType selector, you can obtain a speech version information structure, which provides information about the speech synthesizer currently being used.
A unique identification of a synthesizer engine. If you develop synthesizers, then you should register a different four-character code for each synthesizer you develop with Developer Technical Support. The creatorID field of the voice specification structure and the synthCreator field of a speech extension data structure should each be set to the value stored in this field for the desired synthesizer.
The specific type of the synthesizer. Currently, no specific types of synthesizer are defined. If you define a new type of synthesizer, you should register the four-character code for your type with Developer Technical Support.
The general type of the synthesizer. For the current version of the Speech Synthesis Manager, this field always contains the value kTextToSpeechSynthType, indicating that the synthesizer converts text into speech.