What does the gramophone recording state? Who plays the gramophone announcement?

Suddenly, a voice comes booming into the room. None of the guests can tell where it is coming from. The voice tells the guests that they “are charged with the following indictments.” The voice lists the names of each guest and accuses each of committing murder on a particular date. At the end, the voice says, “Prisoners at the bar, have you anything to say in your defense?” There is a moment of silence, then a scream and a thud.