1.2.4 Barge-In and Voice Event Signaling

The combination of echo cancellation (EC) and voice activity detector (VAD) can be used to effect barge-in, the act of speaking over a prompt. EC significantly reduces the echo of the prompt from the incoming speech signal. The VAD detects the beginning of an utterance and optionally can send a VAD event to the host application.

The barge-in feature stops the playing of the prompt upon detection of audio energy exceeding the threshold. For some applications, you may choose to halt the prompt based on other criteria; for example, only after the caller utters a valid vocabulary word. In this case, CSP can be set to inform the application that energy has been detected without terminating the prompt playback. This is called voice event signaling. CSP then sends the pre-speech buffer followed by the speech buffers in real time to the application.

For more information on setting barge-in and sending notification to the host application, see Section5.1.2, Stopping Play When Speech is Detected (Barge-In) and Section5.1.1, Sending a VAD Event to the Host Application. For detailed function and parameter descriptions, see ec_setparm( ) in the Continuous Speech Processing API Library Reference.

Click here to contact Dialogic Customer Engineering