Among the new bits in .NET 3.0 is the SpeechSynthesizer class that exposes SAPI's functionality to managed code without having to resort to P/Invoke.  SpeechSynthesizer is located in the System.Speech.Synthesis namespace.  To speak text, we simply call Speak() or SpeakAsync() with a string containing the text to be spoken.  To terminate the speech, call SpeakAsyncCancelAll().

  1   SpeechSynthesizer ss = new SpeechSynthesizer();
  2   ss.SpeakAsync ("Hello, world");
  3   ...
  4   ss.SpeakAsyncCancelAll();

The speech is spoken using the object's current properties of Voice, Rate and Volume.  Voice is the name of an installed voice, Rate is an integer between -10 and 10, and Volume is an integer between 0 and 100 and represents the percentage of the audio device's main volume.  The list of installed voices is obtained by calling GetInstalledVoices() as shown below.

  1   ReadOnlyCollection<InstalledVoice>
  2     voices = ss.GetInstalledVoices();
  3   if (voices.Count > 0)
  4       ss.Voice = voices[0];

Saving the spoken text as a .WAV file is easily done by directing the synthesizer's output to the file, speaking the text, and redirecting the output to the default audio device.

  1   // Save speech as .WAV file
  2   ss.SetOutputToWaveFile ("C:\\hello.wav");
  3   ss.Speak ("Hello, world");
  4   ss.SetOutputToDefaultAudioDevice();

And there you have it - speech synthesis in a few words.