In Harry Potter and the Deathly Hallows, there is a sound that comes from the feet of the Death Eaters when they are meeting at Malfoy Manor.
At these words, seemingly in response to them, a sudden wail sounded, a terrible, drawn-out cry of misery and pain. Many of those at the table looked downward, startled, for the sound had seemed to issue from below their feet.
I have always assumed the sound to come from Professor Burbage. Voldemort even says:
“Wormtail,” said Voldemort, with no change in his quiet, thoughtful tone, and without removing his eyes from the revolving body above, “have I not spoken to you about keeping our prisoner quiet?”
Due to him looking at Burbage while speaking to Pettigrew, I've always assumed "our prisoner" was referring to her.
However, Professor Burbage is stated to be above the table, not below it.
As their eyes grew accustomed to the lack of light, they were drawn upward to the strangest feature of the scene: an apparently unconscious human figure hanging upside down over the table, revolving slowly as if suspended by an invisible rope, and reflected in the mirror and in the bare, polished surface of the table below.
Therefore, what was the sound coming from below the Death Eaters' feet?
Is it another prisoner in the basement making the sound? Perhaps Ollivander?