Good Read Who Was Mark Twain? Who Was... ? Series by John A. O'Brien (Illustrator); April Jones Prince; Nancy Harrison (Illustrator) Copyright Year: 2004 ISBN-13: 9780448433196 Video Preview Available format(s): VOICEText (H) Add to Bookshelf What's an Audio Format Audio format refers to the way an audiobook is recorded. Not all audiobooks have the same formats. Classic Audio: A human reading an audiobook without the text displayed. VOICEtext (H): Human narrator with text that you can follow along with as it reads. VOICEtext (S): Synthetic voice with text you can follow along with as it reads.