ISpVoice::SetVolume (SAPI 5.4)
Microsoft Speech API 5.4
ISpVoice::SetVolume sets the synthesizer output volume level of the voice in real time. The default base volume for all voices is 100.
HRESULT SetVolume( USHORT usVolume );
[in] Value containing the requested volume level. Volume levels are specified in percentage values ranging from zero to 100 - values outside this range may be truncated.
SetVolume affects the volume of synthesized WAV data; it does not affect the volume of the .WAV file that is played back. Volume is specified as a percentage of the maximum volume of the current voice. Different voices may have different maximum volume levels.
Applications can adjust the volume of a voice either through this function call, or through XML grammar passed to the voice with the input text of a speak call (see the XML Schema : SAPI white paper). The voice should combine volume adjustments made in these two ways to arrive at a final volume.