The engine must perform the same security checks on access to speech engines as the Central class. EngineCentral is used internally by Central and speech engines. Each object in the list must be a sub-class of either RecognizerModeDesc or SynthesizerModeDesc and must implement the EngineCreate interface. The Central class ensures that the require parameter is an instance of either RecognizerModeDesc or SynthesizerModeDesc . This enables the EngineCentral to optimize its search for either recognizers or synthesizers.
Returns null if no engines are available or if none meet the specified requirements.
The engine can create the list at the time of the call or it may be pre-stored.