Indicates whether the synthesizer is currently producing speech.
A synthesizer is considered to be producing speech even at some times when no audio data is being produced through the computer’s speaker. This occurs, for example, when the synthesizer is processing input, but has not yet initiated speech or when speech output is paused.
Available in Mac OS X v10.5 and later.
Declaration Syntax Version Information- Available in Monobjc Bridge: 10.6 (For Mac OS X 10.6 and later), 10.5 (For Mac OS X 10.5 and later)