How do you check something nobody sees?
You do not — you write the default so that it stays true unchecked. An alt text is read aloud, not looked at; it passes every visual inspection. "Chapter mark." is correct for every book and therefore cannot go stale.
Read the entry: One hundred and forty-two alt texts for the wrong book →
How do you tell that a public-domain text is not in the public domain after all?
By the imprint inside the text and by the overlap with the original. Adapted publisher versions often carry editors' names in the middle of the work and depart substantially from the source — in our case the overlap was 29 per cent. Neither shows on the title page; both show in the full text.
Read the entry: The volume we withdrew →
Can speaker roles for an audiobook be derived automatically from the novel?
Only in one direction. Our segmenter systematically overestimates a character's share of the dialogue — in ten out of ten checked cases, by a factor of 1.6 to 21, because it assigns unclear speakers to the nearest name. What it sees below the threshold is certainly below it; a high figure proves nothing and has to be read against the text.
Read the entry: Ten out of ten estimates were too high →