The barge-in function allows user input, speech or DTMF, to interrupt the play of prompts. A prompt in this case can be a .wav file or text-to-speech (TTS).

The spoken utterance or DTMF tone does not have to match anything for barge-in to occur. The VXML specification has an option for requiring a grammar match, but Edge currently does not support it. Architect sets the default barge-in to true for all audio except for the Hold Music audio, which defaults to false for historical reasons.  

You can set barge-in behavior for each individual queued prompt. When the system plays the prompt, it honors the barge-in setting for each prompt. However, after barge-in triggers, it skips the currently playing prompt to be aborted, as well as any prompts that remain in the queue, regardless of their barge-in settings.