ISpVoice::SetAlertBoundary (SAPI 5.3)

Speech API 5.3
Microsoft Speech API 5.3


ISpVoice::SetAlertBoundary specifies which event should be used as the insertion point for alert priority voice interruptions and ISpVoice::Pause calls.  

HRESULT SetAlertBoundary(
   SPEVENTENUM   eBoundary


[in] SPEVENTENUM enumeration value that specifies which event to use for the alert insertion point. Appropriate events to use for this purpose include SPEI_WORD_BOUNDARY, SPEI_SENTENCE_BOUNDARY, SPEI_PHONEME, SPEI_VISEME, and possibly SPEI_VOICE_CHANGE or SPEI_TTS_BOOKMARK. 

Return values

S_OKFunction completed successfully.
E_INVALIDARGeBoundary is invalid.


Events, such as word and sentence boundaries, are queued by the TTS engine during text rendering. Alert priority voices will only be able to interrupt normal priority voices, and pauses will only be able to occur on the specified event boundaries.

The default alert boundary event is SPEI_WORD_BOUNDARY.

See ISpVoice::SetPriority for more details on voice priorities.