TTS is the ability of the operating system to play back printed text as spoken words. An internal driver, called a TTS engine, recognizes the text and using a synthesized voice chosen from several pre-generated voices, speaks the written text. A TTS engine is installed with the operating system. Additional engines are also available through third-party manufacturers. These engines often use a certain jargon or vocabulary; for example, a vocabulary specializing in medical or legal terminology. They can also use different voices allowing for regional accents such as British English, or speak a different language altogether such as German, French, or Russian.
The Text-to-Speech tab in the Speech tool in Control Panel presents the options for each TTS engine. See the individual Help topics for specific help. In addition to the general options, each engine can have a different set of specific features. For that reason, not all the resulting dialog boxes will look the same. It is possible that no special features have been included and some of the properties buttons will not have an associated dialog box.