Describe NSSpeechSynthesizer here.

NSSpeechSynthesizer is the built in objective-c wrapper around the speech system introduced in 10.3

See http://developer.apple.com/documentation/Cocoa/Reference/ApplicationKit/Classes/NSSpeechSynthesizer_Class

And http://developer.apple.com/documentation/Cocoa/Conceptual/Speech/Articles/SynthesizeSpeech.html