At startup time, the
SpeechSynthesizer component in the Engine opens an audio output channel of type
TTS for the application to play Alexa speech responses to the user.
SpeechSynthesizer has no messages of its own for the application to handle because it uses the standard audio output framework specified in the
Core module. When Alexa responds to a user request with speech, the Engine publishes an
AudioOutput.Prepare message with
TTS. The application uses the payload of the message to open the audio stream and buffer the audio data. The application plays the audio to the user when the Engine publishes an
AudioOutput.Play message with matching