Voice events return the input stream number in order to associate them with the appropriate stream. If the event type is of interest, an event of that type is raised. At each event boundary, the event type is compared with the current EventInterests. The point in the input text stream at which a potential event has been completed is referred to as an event boundary. To prevent the TTS engine from generating events that will be ignored by the application, use the EventInterests property to specify the events of interest. The range of conditions which can be reported by SpeechVoiceEvents is wide enough that most applications will use only a few of them. Examples of these events are completion of phonemes, words, or sentences, as well as changes of voice or the presence of bookmarks. These events are contained in the SpeechVoiceEvents enumeration. Voice EventsДЄs a voice speaks text, it can generate events when it detects certain conditions in the input stream.

Use the AudioOutputStream property with other Speech automation objects to store audio output in memory (see SpMemoryStream) or in files (see SpFileStream). Use the GetAudioOutputs method to determine what other outputs are available to the voice, and use the AudioOutput property to set its audio output to one of them. Voice OutputДЄn SpVoice object is created with its audio output set to the system default audio output. The SpeakStream method operates like the Speak method, except that it speaks sound files instead of text. The hidden SpeakCompleteEvent method is similar to WaitUntilDone, except that it returns an event handle for the background speaking process, and does not block application execution. The WaitUntilDone method blocks execution until the voice finishes speaking, enabling an application to speak a text stream asynchronously and determine when it finishes. The stream number returned by an asynchronous Speak call is the stream's index in the voice queue. These streams are also referred to as speech requests. This may be acceptable for simple applications, or those with no graphical user interface (GUI), but when sophisticated user interaction is intended, asynchronous speaking will generally be more appropriate.ДЄsynchronous speaking can place numerous text streams into the input queue. When synchronous speech is used in an application, the application's execution is blocked while the voice speaks, and the user is effectively locked out. When called synchronously, the Speak method does not return until the text has been spoken when called asynchronously, it returns immediately, and the voice speaks as a background process. It can be called synchronously or asynchronously. The Speak method places a text stream in the TTS engine's input queue and returns a stream number. The TTS tab of Speech properties in Control Panel, which enables users to modify the characteristics of the default system voice, is an example of a voice UI. Use the DisplayUI method to display a supported UI. The IsUISupported method determines if a specific UI is supported. These properties can be modified with a User Interface (UI). Use the GetVoices method to determine what other voices are available to the voice object. 'Microsoft Mary' and 'Microsoft Mike' are examples of Voices. The fundamental characteristics of the voice are the Voice property, which can be thought of as the person of the voice, the Rate property, and the Volume property. An SpVoice object, usually referred to simply as a voice, is created with default property settings so that it is ready to speak immediately. An application can create numerous SpVoice objects, each independent of and capable of interacting with the others.

The SpVoice object brings the text-to-speech (TTS) engine capabilities to applications using SAPI automation.

Windows 10 voices sapi