17. A computer program product comprising computer code stored on a computer readable storage device configured when executed on a processor to cause operations of: establishing a voice or video call between at least a source user speaking a source language and a target user speaking a target language; outputting an audio translation of the source user's speech in the target language to the target user, the translation generated by performing an automatic translation procedure on call audio of the call which comprises speech of the source user in the source language; and outputting a notification to the target user to notify the target user of a change in behaviour of the translation procedure, the change relating to the generation of the translation and the notification including a synthetic video embodied as a visual action by an animated avatar mimicking visual cues of a human.
17. A computer program product comprising computer code stored on a computer readable storage device configured when executed on a processor to cause operations of: establishing a voice or video call between at least a source user speaking a source language and a target user speaking a target language; outputting an audio translation of the source user's speech in the target language to the target user, the translation generated by performing an automatic translation procedure on call audio of the call which comprises speech of the source user in the source language; and outputting a notification to the target user to notify the target user of a change in behaviour of the translation procedure, the change relating to the generation of the translation and the notification including a synthetic video embodied as a visual action by an animated avatar mimicking visual cues of a human. 19. The computer program product according to claim 17 wherein the change in the behaviour is the translation procedure entering a passive translation state responsive to the source user commencing a period of speech activity, in which the translation procedure is monitoring current speech activity by the source user in the call audio.