These were just two of the thousands of custom effects created for the reimagined audiobooks from Audible, which feature more than 200 actors (including Keira Knightley, Matthew Macfadyen, Hugh Laurie and Kit Harington) voicing more than 500 characters, a 60-piece orchestra playing an original score and an immersive soundscape that brings the text to life. The first book, “Harry Potter and the Sorcerer’s Stone,” was released on Nov. 4; the others will follow over the next six months.